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Explaining trends in inequities: evidence from Brazilian child health studies
PUBLIC HEALTH
Public health
Explaining trends in inequities: evidence from Brazilian child health studies Cesar G Victora, J Patrick Vaughan, Fernando C Barros, Anamaria C Silva, Elaine Tomasi There is considerable international concern that child-health inequities seem to be getting worse between and within richer and poorer countries. The “inverse equity hypothesis” is proposed to explain how such health inequities may get worse, remain the same, or improve over time. We postulate that as new public-health interventions and programmes initially reach those of higher socioeconomic status and only later affect the poor, there are early increases in inequity ratios for coverage, morbidity, and mortality indicators. Inequities only improve later when the rich have achieved new minimum achievable levels for morbidity and mortality and the poor gain greater access to the interventions. The hypothesis was examined using three epidemiological data sets for time trends in child-health inequities within Brazil. Time trends for inequity ratios for morbidity and mortality, which were consistent with the hypothesis, showed both improvements and deterioration over time, despite the indicators showing absolute improvements in health status between rich and poor. The question of whether inequities can be reduced by public-health intervention has been previously addressed in the context of real-life maternal and child health programmes in Brazil. As a corollary to the “inverse care law” on individual medical care, we propose the “inverse equity hypothesis” to explain how inequities between rich and poor respond to public-health programmes or packages of interventions. We postulate that new interventions will initially reach those of higher socioeconomic status and only later affect the poor. This results in an early increase in inequity ratios for coverage, morbidity, and mortality indicators, followed later by a reduction when the poor gain greater access to the interventions and the rich reach minimum achievable levels for morbidity and mortality, beyond which there are unlikely to be substantial further improvements. Here, we have assessed three epidemiological data sets for time trends in inequities. In all three, morbidity and mortality indicators seem to be improving in absolute terms for both rich and poor, and absolute differences are narrowing down. However, inequity ratios tended to decrease only when the wealthy had reached a new minimum achievable level for morbidity or mortality for those public-health interventions. Public-health interventions are essential to prevent further deterioration of inequities in health status in countries where government funding for health services is likely to be reduced as a part of the trend towards neoliberalism.
Inequities and public health Although health status has been improving for most countries, wide inequities persist both between and within countries.1–6 In more-developed countries evidence Lancet 2000; 356: 1093–98 Post-Graduate Programme in Epidemiology, Federal University of Pelotas, Brazil (Prof C G Victora MD, E Tomasi BA); Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK (Prof J P Vaughan MD); Latin American Center for Perinatology, Montevideo, Uruguay (F C Barros MD); and Hospital Albert Sabin, Fortaleza, Brazil (A C Silva MD) Correspondence to: Prof J Patrick Vaughan, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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suggests that such inequities commonly show an increase despite an improvement in the overall health status of the whole population. However, there is also some evidence to show that reductions in inequities can also be achieved, at least in more-developed countries.7 Inequities are particularly severe in the Americas, where Brazil, Guatemala, and Paraguay rank second, third, and fourth in the world in terms of income concentration.8 The PanAmerican Health Organization has recently declared that “inequity continues to be the leading health problem in the Americas.”9 Almost 30-years ago, Julian Tudor-Hart10 proposed the “inverse care law”, which stated that the availability of good medical care tends to vary inversely with the need for it in the population served. This proposition, which was largely commenting on medical care for patients, is now widely accepted. A logical corollary is that “a new health intervention will tend to increase inequities”, because the intervention will initially reach those people with a higher socioeconomic status rather than the poor. Of interest to policy makers, therefore, is whether new public-health interventions—as well as general improvements in health—can actually reduce inequities in health status between rich and poor groups in society. There is limited evidence on this issue, particularly from less-developed countries, because this requires good quality data on long-term trends in health indicators and socioeconomic status, or at least two sequential assessments of health and socioeconomic status in the same geographical population through use of comparable methodologies. We present a hypothesis and explanation as to why, following the introduction of new public-health interventions, inequities in infant and child health status between richer and poorer groups in society usually widen before they get smaller and improve. We have called this the “inverse equity hypothesis”. We examined data from three studies that analysed trends in indicators of coverage, morbidity, and mortality. First, we present an analysis on inequities in infant and child mortality trends between countries in the Americas. Second, we present data on health impact of a large-scale public health programme to improve child health in the poor Ceará State in the
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PUBLIC HEALTH
Wealthy
10 0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
5
Ratio poor/wealthy
4 3 2 1 0
Time (years) Figure 1: Morbidity or mortality outcome indicators and rate ratios Top: Hypothetical trends in morbidity or mortality outcome indicators in poor and wealthy subpopulations. Bottom: Corresponding rate ratios.
northeast of Brazil. Finally, the findings from two birth cohort studies, implemented more than a decade apart, are presented for the city of Pelotas in southern Brazil. In these analyses, we have used ratio measures of inequity, rather than absolute or difference measures. For example, if infant mortality rates (IMRs) are equal to 80 deaths per 1000 live births for the poorest subgroup and equal to 20 for the wealthiest, the absolute gap is equal to 60 deaths per 1000, and the rate ratio is equal to four. If, as a consequence of an intervention, the IMR for the poor decreases to 50 and for the wealthy to ten, the difference becomes 40 deaths per thousand—lower than the initial difference—whereas the ratio is now five, greater than the baseline ratio. Difference measures will almost inevitably lead to an apparent reduction in equity gaps, because baseline rates tend to be already low in absolute terms among the wealthiest. Ratio scales, however, take baseline levels into account and are thus more appropriate for deciding whether or not inequity is decreasing. This is consistent with the use of ratio measures in epidemiological research.
The inverse equity hypothesis How can we explain epidemiological trends that show that inequities between rich and poor commonly become worse before showing signs of improving? Figure 1 proposes time trends for hypothetical outcome indicators, such as disease incidence or mortality, in the richest and poorest subgroups in the general population, and presents the corresponding inequity ratios obtained by dividing the level of the outcome in the poor by that in the rich.
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Infant mortality 12 Median to lowest mortality country
10
Brazil to lowest mortality country
8 Ratio
Outcome (log)
Poor
At 1 year the initial inequity in the outcome has a rate ratio of 3·0, which means that the poor are three times worse off than the rich. However, when the new intervention is introduced at year 2 it is initially taken up preferentially by the richer subgroup, as predicted by the “invese equity hypothesis”. A high coverage is rapidly achieved by the rich and by time three the value of their outcome indicator begins to stabilise at a much lower level. A new “minimum achievable level” in morbidity or mortality has been reached at this point and only small further reductions are possible. Between year 3 and 4 inequity, expressed as the rate ratio, widened from 3·0 to about 4·5. At year 4, however, coverage for the interventions starts to increase among the poor, but at a slower rate than it did previously among the rich. At year 5 the inequity ratio or gap has been reduced and it is now back to the original value of 3·0. Scope for further reductions may be greater among the poor, because of their higher initial levels of morbidity or mortality: thus at time six the further improvement in the inequity ratio, now at 2·0, means that equity is now better than at any time since the trends were first seen. The proposed “inverse equity hypothesis” thus attempts to explain why at different times the inequity ratio between rich and poor can improve, remain unchanged, or get worse. Obvously decreases in the inequity ratio suggest that equity is improving. A direct test of this hypothesis is difficult because there are few if any examples of a single health intervention being the sole factor contributing to the decline of a given disease. In real life, multiple interventions are usually present for any single disease and each intervention will have variable coverage levels in different social groups. Given the complexity of real-life trends, whether health inequities increase or decrease will depend on: which
6 4 2 0
1960s
1990s
Child (1-4 year) mortality 12 10 Ratio
100
8 6 4 2 0
1960s 1990s Figure 2: Inequity ratios for national infant and child mortality rates in the Americas11 Source: Pan-American Health Organization.
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PUBLIC HEALTH
effective interventions are available, and for how long and at what quality and coverage—for the wealthy and poor subgroups of the population—since different interventions may vary in their contribution to health improvement in these subgroups; the underlying levels and component causes of disease in these subgroups; and whether or not the rich have already attained the minimum achievable incidence or mortality level with currently available interventions. Taking these variations into account, we examined three case studies that related to recent trends in child health in Brazil.
Inequities in infant and child mortality Information on time trends for IMR and child (1–4 years) mortality rates (IMR) in American countries is based on a Pan-American Health Organization document on mortality trends and initial levels.11 This document showed that both rates had decreased substantially since the 1960s. For this study we estimated inequities in mortality between countries by identifying which country had the median level of infant and child mortality in the Americas, and then dividing these national rates by those for the country with the lowest rate (the USA until 1979 and Canada from 1980 onwards). Figure 2 shows that the median national IMR in the 1960s was 4·5 times higher than for the lowest IMR country, but this inequity ratio increased steadily to reach six in the 1990s. During the same period the ratio between the countries with the highest and lowest IMR had doubled, increasing from about 7 to 14. The interquartile range also increased. For Brazil in the 1960s the IMR was about four times greater than for the lowest mortality country and this ratio doubled to about eight times greater in the 1990s. Thus, although the IMRs had clearly fallen in the Americas, inequities between countries had substantially increased. Child mortality rates (CMR) also fell in the Americas, but the lowest mortality countries seem to have reached a stable minimum level—of about 0·3 per 1000—below which further reductions were likely to be small, given currently available interventions. Contrary to the findings for infant mortality, from the 1960s to 1990s the inequity ratio between the median and lowest child mortality countries in the Americas were nearly halved, falling from about 11 to six times greater. Brazil showed a similar pattern, with the ratio of its CMR to that for the lowest mortality country falling from 12 in the 1960s to five in the 1990s.12 Thus, during 3 decades inequities for child mortality showed an improvement in both the Americas and in Brazil. How does the “inverse equity hypothesis” explain how inequity in the Americas apparently became far worse for infant mortality whereas it improved for child mortality? The results can be interpreted in the light of the hypothetical curves presented in figure 1. Even though infant mortality rates were initially lower in the wealthiest countries, there was still considerable scope for improvement and their rates declined faster than for the intermediate and poorest countries when newly available technologies spread more rapidly in rich countries than in poor countries. Hence the inequity gap increased. For child mortality, however, the richest countries had reached the minimum achievable level much earlier whereas in the poorest countries mortality was still falling in the 1990s. Thus inequity, as measured by CMR ratios, has been reduced, and equity appears to have improved substantially.
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This example does not allow a direct test of the inverse equity hypothesis, since several interventions—as well as economic changes—were taking place simultaneously. Nevertheless, the American example suggests that inequity between countries will tend to be reduced only when the rich nations have reached such low levels that further gains are unlikely.
Inequities in Ceará, northeastern Brazil Evidence that public-health interventions or packages can help in reducing inequities between rich and poor was also sought for the State of Ceará, in the poor northeastern area of Brazil. Early in the 1980s the IMR was above 100 per 1000 and malnutrition was very common. In 1986 the new State government requested UNICEF support to help improve child health and a statewide survey of child health and nutrition was commissioned. More than 4500 childen younger than 3-years old were surveyed by visiting 8000 families in a probability sample of 40 different municipalities.13 Based on the survey conclusions, new health policies were implemented, including the GOBI strategy of growth monitoring, oral rehydration, breastfeeding promotion, immunisation, and vitamin-A supplementation. Since lack of access to health-care facilities was a major problem, a large new programme for community health workers was established and another programme for traditional birth attendants14 was expanded. Responsiblity for health services was decentralised to rural munipalities, which were the ones with the worst health indicators. A social mobilisation campaign for child health was implemented, which included the use of the media and small radio stations to broadcast educational messages. Similar surveys were repeated again in 1990 and 199415 and after each one the results were incorporated into health policy. This process was sustained by four consecutive state governors who all give high priority to improving child health. The experience in Ceará drew international attention and in 1993 the State received the Maurice Pate Award, the annual UNICEF prize for successful progress towards child health and well-being. Considerable advances in the population coverage of the four GOBI interventions from 1987–94 are shown in figure 3. By 1994 the use of oral rehydration solution had increased to more than 50% in children with diarrhoea, nearly all children had a growth chart and a half had been weighed within the previous 3 months, immunisation coverage was 90% or higher, and median breastfeeding duration—a difficult indicator to improve—had apparently increased from 4·0 to 6·9 months. 1987
1994
Measles vaccination Diphtheria toxoid vaccination Use of oral rehydration solution Median time child was breastfed
4·0 months 6·9 months
Ever breastfed Child weighed in past 3 months Growth chart available 0%
20% 40% 60% 80% 100%
Figure 3: Evolution of child-health programme coverage indicators, Ceará State 1987–94
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Indicator
Number of children Percentage of children aged 12–35 months who received all vaccines scheduled for the first year Percentage of children weighed in the 3 months before the survey Percentage of children aged 6–35 months who were breastfed for 6 months or longer Percentage of children with diarrhoea in the previous 2 weeks Percentage of children with diarrhoea who received an oral rehydration solution Percentage of children with weight for age below ⫺2 z scores Percentage of children aged 12 months with length for age below ⫺2 z scores
Year
1987 1994 1987 1994 1987 1994 1987 1994 1987 1994 1987 1994 1987 1994 1987 1994
Family income groups (US$ per month) <60
60–119
120–299
肁300
2026 1207 30 87 24 60 48 52 28 16 19 51 16 12 34 23
1272 609 38 88 31 65 38 49 27 15 26 59 12 8 27 17
619 501 40 93 38 69 36 46 25 13 30 54 8 5 19 10
352 137 44 96 53 69 29 38 19 10 32 47 6 3 9 8
Ratio poor/rich
All children
5·8 8·8 0·68 0·91 0·45 0·87 1·70 1·40 1·50 1·60 0·59 1·10 2·70 4·00 3·80 2·90
4269 2454 35 89 30 64 42 49 26 14 23 54 13 98 28 18
Table 1: Health indicators for children under 3 years of age in the 1987 and 1994 statewide surveys, by income group
Disease frequency and mortality outcome indicators for the whole population also showed considerable improvement between 1987 and 1994. The prevalence of low weight-for-age (below ⫺2 z scores of the National Center for Health Statistics16) fell from 12·7% to 9·2%, low height-for-age from 27·4% to 17·7%, and reported episodes of diarrhoea in children in the previous 2 weeks from 26·1% to 13·6%. Infant mortality was estimated by asking mothers to provide birth histories of children born in the 3 years before the survey. In 1987 the IMR was estimated at 63 per 1000 live births compared with 39 per 1000 in 1994, a 37% reduction. Based on verbal autopsies, diarrhoea proportionate mortality—a priority for the health programme—fell from 48% to 29%, whereas perinatal causes of infant deaths increased from 7% to 21% and respiratory infections from 10% to 25%. Deaths due to other causes, including infections other than diarrhoea and respiratory infections, fell from 35% to 25%. Although these trends in improving population health were clearly substantial, it is important to analyse these trends by richer and poorer socioeconomic subgroups in the whole population. The results in table 1 indicate that the emphasis on reaching the poorest families has been successful in reducing inequity in coverage indicators between the rich and poor. Immunisation rates improved remarkably in all income groups, with the inequity gap between rich and poor closing as the wealthy reached near universal coverage. For both growth monitoring and use of oral rehydration solution, the inequity gap was also narrowed. Assessment of breastfeeding duration showed that in 1987 it was longer among the poorest, whereas by 1994 the gap between rich and poor had now narrowed in favour of the wealthier—an interesting “trickle up” phenomenon, since health messages had been primarily directed to the poorest people. Despite the progress achieved in improving coverage for public-health interventions, inequity between rich and poor for disease frequency and infant mortality remained largely unchanged between 1987 and 1994. The proportions of children in the extreme categories of family income remained almost the same in both years, showing that income inequalities had persisted and remained largely unchanged. Cases of diarrhoea remained about 60% higher among the poor. Possible explanations for the declines seen in both rich and poor groups were increases in breastfeeding duration and in sanitation programmes. Also, the ratio in the prevalence of underweight and stunted children changed only slightly during the period.
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Because of the small number of children in the highest income group in 1994, however, results for this group are hard to interpret. As mortality data stratified by family income were not available, infants deaths during the 3 years before each survey were analysed according to maternal literacy groups. The odds ratios for the IMRs among the infants of illiterate compared with literate mothers were 1·56 (95% CI 1·14–3·01) in 1987 and 2·48 (1·57–3·90) in 1994. Thus, although the overall literacy rate had risen from 82·0% to 86·7%, this overall improvement could not account for the difference seen in the point estimates. In Ceará, despite the implementation of child-health interventions for the poorest families, inequities appeared to remain largely unchanged for four health status impact indicators—weight, stunted growth, prevalence of diarrhoea, and infant mortality. Despite an overall improvement in health, the inequity ratio between rich and poor remained the same. An explanation is that wealthy families had made greater and earlier use of both public sector and private services to protect their children’s health. The conclusions from Ceará suggest that, even with public-health programmes targeted at the poorest, it is difficult to close the inequity ratio group if the rich have not yet achieved high levels of vaccination coverage and consequently low levels of morbidity or mortality. These findings support the predicitons of the “inverse equity hypothesis” that inequity gaps in health status between rich and poor will only be reduced when wealthier families achieve low morbidity and mortality levels, beyond which further progress is difficult—if not impossible—given the current state of public-health interventions.
Inequities in Pelotas, Southern Brazil Good epidemiological evidence from cohort studies done in the city of Pelotas in 1982 and 1993 suggest that inequities can be reduced by public-health programmes. Pelotas is in a relatively developed area in southern Brazil. During 1982 more than 6000 births were studied and this cohort—who are now adolescents—are still being followed up.17 In 1993 another similar birth cohort of 5000 newborn babies was studied.18 Both studies were population based and had high follow-up rates. There was a slight improvement in income distribution during this period (table 2) but wide differentials had persisted. The data analysis used five family income groups, based on the local minimum wage (worth about US$60 during this period). Between 1982 and 1993 there were important changes in health-care delivery in Pelotas and the number of
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PUBLIC HEALTH Indicator
Year
Number of births Percentage of mothers with antenatal care starting before the fifth month of pregnancy Percentage of children with three doses of diphtheria toxoid in first year of life Percentage of children aged 12 months with weight for age below –2 z scores (NCHS) Infant mortality rate (per 1000) Caesarean section rate (%)
Family income groups (US$ per month)
Ratio 肁600
All children poor/rich
60
60–179
180–359
360–599
1982 1993 1982 1993
1321 984 74 84
2837 2166 83 90
1105 1217 93 93
383 437 96 96
336 386 98 97
3·9 2·5 0·76 0·87
1982 1993 1982 1993 1982 1993 1982 1993
72 85 14 9 80 33 19 23
82 89 5 4 34 26 26 25
89 91 1 1 17 10 36 33
94 96 1 0 20 11 43 45
96 94 1 2 13 5 47 56
0·75 0·90 14·0 4·50 6·20 6·60 0·40 0·41
6011* 5304* 85 91 83 90 5 4 36 21 28 31
*Information on family income was missing for 29 and 113 children in 1982 and 1993, respectively.
Table 2: Health indicators in the 1982 and 1993 birth cohorts, by income group, in Pelotas, Brazil
government primary health-care facilities increased from about ten to more than 50. In addition, three neonatal intensive-care units were installed, although such facilities did not serve all the newborn babies in need. There was also an important expansion of government public health and curative programmes. Public-health policies implemented in Pelotas during this period were typical of those commonly adopted in such middle-income countries, with health interventions being made generally available, rather than targeted at the poorest people. Table 2 shows that these changes in health programmes had a substantial effect on inequities as measured by programme coverage. For instance, for both antenatal-care attendance and the take up of immunisations the coverage ratio between rich and poor was reduced as the levels among the poor were raised closer to the high levels already achieved by the rich. Similar improvements in equity, as measured by coverage, were also found for other variables, such as growth monitoring and use of oral rehyration fluids. The prevalence of low weight-for-age at 12 months (below ⫺2 z scores relative to the National Center for Health Statistics16) decreased slightly from 5·4% in 1982 to 3·7% in 1993. Table 3 also shows a large fall from 14% to 9% among the poorest, whereas the three highest income categories remained at between 1% and 2%. Since 2·3% of all children in a well-nourished population would be expected to be underweight, there was little chance of improvement in the three highest income categories. Inequities improved, therefore, largely because the wealthy had already reached a minimum achievable level. Although the IMR fell in Pelotas city from 36 to 21 per 1000 live births between 1982 and 1993, table 2 shows that the mortality rate ratio remained unchanged throughout the decade, with seven times as many poor children dying than wealthy children. To explain why this gap remained, death rates in 1982 and 1993 were stratified according to four combinations of family income and birthweight, a major proximate determinant of infant mortality (table 3). To ensure sufficient sample sizes, families were divided into two groups according to whether income was above or below US$240 a month. Family income group (US$ per month)
<180 肁180
Birthweight (g)
<2500 肁2500 <2500 肁2500
Infant mortality rate (per 1000) 1982
1993
220 25 148 5
141 12 48 5
Percentage 1982–93
36 52 68 0
Table 3: Infant mortality rates in the 1982 and 1993 birth cohorts, by income and birthweight group in Pelotas, Brazil
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The results were striking. There was no improvement in the mortality of wealthy children born with an appropriate birthweight, since their mortality was already at the low level of five per 1000 in 1982, probably the minimum achievable. However, mortality in infants of normal birthweight born into poor families fell by 52%, largely attributable to improvements in the prevention and management of infectious diseases (data not shown). Equity thus improved for infants with appropriate birthweight, with the ratio being halved from 1982 to 1993, from a 5-fold to a 2·4-fold difference. For low-birthweight infants, however, inequities increased substantially throughout the decade. Mortality among these infants fell by 68% for the rich families compared with only 36% among the poor. This was despite the already lower starting level among the richer subgroup since clearly the minimum achievable level had not been achieved in 1982 by either the rich or poor. Thus, the inequity gap increased from 1·5 times in 1982 to 2·9 in 1993. The most likely explanation is that the introduction of new technologies for neonatal intensive care and surfactant therapy were rapidly adopted by the wealthy but were not being accessed to a sufficient coverage level by the poorer families. This explanation was confirmed by the opinions of the neonatologists and obstetricians working in the city’s hospitals and private clinics. It is worth pointing out, however, that not all inequities benefit the rich. Table 2 also shows the rates of caesarean births in Pelotas in 1982 and 1993 by family income groups. Assuming these should not exceed 15% of all deliveries, all income groups in Pelotas were at an increased risk of unnecessary surgery. Women from the wealthiest subgroup in 1993, however were far more likely to have a surgical than a normal vaginal delivery.19,20 Findings on inequity from the Pelotas cohort studies suggest that public-health programmes can improve the health of the poorest children. However, reductions in inequity can be explained by the improvements occurring among the poorer families while the richer ones already had good levels of health. For infant mortality, where reductions for the wealthy were still possible, the inequity gap persisted or even increased, largely because of a combination of improvements in the mortality of appropriate birthweight children balanced against a widening gap in the mortality of low birthweight babies. However, the predictions of the “inverse equity hypothesis” suggest that the infant mortality gap is likely to be reduced in the near future, as the IMR among the poorer families reduces to nearer that of the richer families
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PUBLIC HEALTH
(about five per thousand). The richer subgroup is already at a level found in the world’s lowest mortality countries.21
Conclusion The studies from Ceará and Pelotas suggest that the “inverse equity hypothesis”, a corollary of the “inverse care law” applied to public health, provides a reasonable explanation of several observations. The hypothesis suggests that good quality public-health programmes for improving child health are more available and being utilised by those families who need them least. The hypothesis also predicts that new interventions will tend to increase inequity since they will initially reach those who are already better off. It is only when the wealthy have reached a level of improvement—beyond which publichealth interventions are unlikely to make more progress— that the poor begin to catch up and the inequity gap begins to improve. Thus, only over time will the gap be narrowed. The timing factor is therefore essential in the interpretation of the equity impact of new technologies. Unfortunately, the analysis and interpretation of time trend data for inequities is made more complex by the act that many new health interventions are being introduced all the time. As was shown for infant mortality in Pelotas, it is only when interventions have had their maximum impact on the wealthy groups that the inequity gap with the poor begins to improve. However, mortality among the rich is now being further reduced by new perinatal interventions that have yet to fully reach the poor. In addition, morbidity and mortality levels obviously can be prevented from deteriorating. However, they also depend on concomitant changes in socioeconomic, demographic, and environmental factors—factors that also interact with the public-health interventions themselves. In the case of Ceará and Pelotas there is no reason to believe that slower progress among the poor was due to a deterioration in their standard of living. On the contrary, during the study period in Ceará there was a substantial reduction in fertility and some socioeconomic improvement, as well as progress in sanitation and health care,22 and in Pelotas the stake of the poorest improved between the two birth cohorts.23 The persistence of the inequity gaps should not be attributed, therefore, to a deterioration in non-health-sector factors affecting health status, but to the fact that an increasing proportion of the rich were making use of newer technologies that were still unavailable to most of the poor. The conclusions as to whether public-health programmes can impact on inequities appears to be both optimistic and pessimistic. The optimistic conclusions are that, first, to raise programme coverage levels among both rich and poor is possible and, second, that inequities in morbidity and mortality rates may improve given time. The other good news is that health indicators seem to be improving for all social groups and should continue to do so in the future if the availability of social programmes is not curtailed by political or economic crises. In absolute terms, therefore, fewer and fewer children are being adversely affected in all social groups. The pessimistic conclusion is that public-health programmes specifically targeted towards the poorest— such as in Ceará—may not succeed in closing the overall gap in child health within a reasonable time period. However, such programmes may perhaps prevent the inequities from deteriorating even further. We would argue that investment in public-health interventions is a priority in order to prevent inequities
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becoming worse among poor people in the developing world. This is particularly true given the current global trends toward neoliberalism and a reduced state role in financing the health sector. In most less-developed societies, the wealthiest are likely to continue to benefit from the introduction of new health technologies. Unless investment is also made to make existing and new interventions more widely accessible to the poorest, inequity gaps may widen rather than be reduced. Data on mortality trends in the Americas were kindly provided by J A Casas and J N Dachs from the Pan-American Health Organization. The Pelotas studies were financed by IDRC, ODA (now DfID), and the European Commission. The Ceará surveys were funded by UNICEF and by the State Government. We thank other members of the research team Francisca Maria Andrade, Luciano Correa, and Jay MacAuliffe.
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Anon. Health inequality: the UK’s biggest issue. Lancet 1997; 349: 1185. Anon. Lower socio-economic status and increased mortality. JAMA 1998; 279: 1745. Mackenbach JP, Kunst AE, Cavellars AE, Groenhof F, Guerts JJ. Socioeconomic inequalities in morbidity and mortality in Western Europe: the EU Working Group on Socioeconomic Inequalities in Health. Lancet 1997; 349: 1655–59. Graham H. Inquiry into inequalities in health. Health Variations 1998; 3: 2–4. Black D, Morris JN, Smith C, Townsend P. Better benefits for health: plan to implement the central recommendations of the Acheson Report. BMJ 1999; 318: 724–27. Jozan P, Forster DP. Social inequalities and health: ecological study of mortality in Budapest, 1980–83 and 1990–93. BMJ 1999; 318: 914–15. Whitehead M, Drever F. Narrowing social inequalities in health? Analysis of trends in mortality among babies of lone parents. BMJ 1999; 318: 908–12. World Bank. World Development Report 1998/99. Washington: World Bank, 1999. Pan-American Health Organization. Leading Pan-American Health. Washington: PAHO, 1998 (Official Document 287). Hart JT. The inverse care law. Lancet 1971; 1: 405–12. Casas JA, Dachs JN, Bambas A. Health disparities in Latin America and the Caribbean: the role of social and economic determinants. In: Casas JA, Bambas A, Dachs JM, eds. Equity and health in the Americas: perspectives from the Pan-American Health Organization, Washington, DC (in press). Pan American Health Organization. Health in the Americas. Washington: PAHO, 1998 (Scientific Publication 569). Victora CG, Barros FC, Tomasi E, et al. Saúde mterno-infantil nos estados do Ceará, Rio Grande do Norte e Sergipe: aplicação de uma metodologia para diagnosticos comunitarios. Revista de Saúde Pública 1991; 25: 218–25. Araujo G, Araujo L, Janowitz B, Wallace S, Potts M. Improving obstetric care in northeast Brazil. Bull Pan Am Health Organ 1983; 17: 233–42. Silva AMC. Evolução da saúde da criança no Ceará: um retrato de dois momentos: 1987–1994. Fortaleza: Universidade Federal do Ceará, 1998 (Master’s thesis). WHO. Expert Committee on Nutrition. Physical status: uses and interpretation of anthropometry. WHO Technical Report Series. Geneva: WHO, 1995: 854. Barros FC, Victora CG, Vaughan JP. The Pelotas birth cohort study, 1982–1987: strategies for following up 6,000 children in a developing country. Paediatr Perinat Epidemiol 1990; 4: 267–82. Victora CG, Barros FC, Halpern R, et al. Estudo longitudinal da população materno-infantil de Pelotas, localidade da região Sul do Brasil 1993: aspectos metodológicos e resultados preliminares. Rev Saude Publica 1996; 30: 34–45. Barros FC, Vaughan JP, Victora CG, Huttly SRA. An epidemic of caesarean sections in Brazil? The influence of tubal ligations and socioeconomic status. Lancet 1991; 338: 167–69. Barros FC, Victora CG, Morris SS. Caesarean sections in Brazil. Lancet 1996; 347: 839. UNICEF. State of the world’s children 1999. New York: UNICEF, 1999. Monteiro CA, Benicio MH, Freitas ICM. Melhoria em indicadores de saúde associados à pobreza no Brasil dos anos 90: descrição, causas e impacto sobre desigualdades regionais. São Paulo: NUPENS/USP, 1997. Tomasi E, Barros FC, Victora CG. Situação socioeconômica e condições de vida: comparação de duas coortes de base populacional no sul do Brasil. Cadernos de Saúde Pública 1996; 12 (suppl): S15–19.
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Public health
Explaining trends in inequities: evidence from Brazilian child health studies Cesar G Victora, J Patrick Vaughan, Fernando C Barros, Anamaria C Silva, Elaine Tomasi There is considerable international concern that child-health inequities seem to be getting worse between and within richer and poorer countries. The “inverse equity hypothesis” is proposed to explain how such health inequities may get worse, remain the same, or improve over time. We postulate that as new public-health interventions and programmes initially reach those of higher socioeconomic status and only later affect the poor, there are early increases in inequity ratios for coverage, morbidity, and mortality indicators. Inequities only improve later when the rich have achieved new minimum achievable levels for morbidity and mortality and the poor gain greater access to the interventions. The hypothesis was examined using three epidemiological data sets for time trends in child-health inequities within Brazil. Time trends for inequity ratios for morbidity and mortality, which were consistent with the hypothesis, showed both improvements and deterioration over time, despite the indicators showing absolute improvements in health status between rich and poor. The question of whether inequities can be reduced by public-health intervention has been previously addressed in the context of real-life maternal and child health programmes in Brazil. As a corollary to the “inverse care law” on individual medical care, we propose the “inverse equity hypothesis” to explain how inequities between rich and poor respond to public-health programmes or packages of interventions. We postulate that new interventions will initially reach those of higher socioeconomic status and only later affect the poor. This results in an early increase in inequity ratios for coverage, morbidity, and mortality indicators, followed later by a reduction when the poor gain greater access to the interventions and the rich reach minimum achievable levels for morbidity and mortality, beyond which there are unlikely to be substantial further improvements. Here, we have assessed three epidemiological data sets for time trends in inequities. In all three, morbidity and mortality indicators seem to be improving in absolute terms for both rich and poor, and absolute differences are narrowing down. However, inequity ratios tended to decrease only when the wealthy had reached a new minimum achievable level for morbidity or mortality for those public-health interventions. Public-health interventions are essential to prevent further deterioration of inequities in health status in countries where government funding for health services is likely to be reduced as a part of the trend towards neoliberalism.
Inequities and public health Although health status has been improving for most countries, wide inequities persist both between and within countries.1–6 In more-developed countries evidence Lancet 2000; 356: 1093–98 Post-Graduate Programme in Epidemiology, Federal University of Pelotas, Brazil (Prof C G Victora MD, E Tomasi BA); Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK (Prof J P Vaughan MD); Latin American Center for Perinatology, Montevideo, Uruguay (F C Barros MD); and Hospital Albert Sabin, Fortaleza, Brazil (A C Silva MD) Correspondence to: Prof J Patrick Vaughan, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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suggests that such inequities commonly show an increase despite an improvement in the overall health status of the whole population. However, there is also some evidence to show that reductions in inequities can also be achieved, at least in more-developed countries.7 Inequities are particularly severe in the Americas, where Brazil, Guatemala, and Paraguay rank second, third, and fourth in the world in terms of income concentration.8 The PanAmerican Health Organization has recently declared that “inequity continues to be the leading health problem in the Americas.”9 Almost 30-years ago, Julian Tudor-Hart10 proposed the “inverse care law”, which stated that the availability of good medical care tends to vary inversely with the need for it in the population served. This proposition, which was largely commenting on medical care for patients, is now widely accepted. A logical corollary is that “a new health intervention will tend to increase inequities”, because the intervention will initially reach those people with a higher socioeconomic status rather than the poor. Of interest to policy makers, therefore, is whether new public-health interventions—as well as general improvements in health—can actually reduce inequities in health status between rich and poor groups in society. There is limited evidence on this issue, particularly from less-developed countries, because this requires good quality data on long-term trends in health indicators and socioeconomic status, or at least two sequential assessments of health and socioeconomic status in the same geographical population through use of comparable methodologies. We present a hypothesis and explanation as to why, following the introduction of new public-health interventions, inequities in infant and child health status between richer and poorer groups in society usually widen before they get smaller and improve. We have called this the “inverse equity hypothesis”. We examined data from three studies that analysed trends in indicators of coverage, morbidity, and mortality. First, we present an analysis on inequities in infant and child mortality trends between countries in the Americas. Second, we present data on health impact of a large-scale public health programme to improve child health in the poor Ceará State in the
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PUBLIC HEALTH
Wealthy
10 0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
5
Ratio poor/wealthy
4 3 2 1 0
Time (years) Figure 1: Morbidity or mortality outcome indicators and rate ratios Top: Hypothetical trends in morbidity or mortality outcome indicators in poor and wealthy subpopulations. Bottom: Corresponding rate ratios.
northeast of Brazil. Finally, the findings from two birth cohort studies, implemented more than a decade apart, are presented for the city of Pelotas in southern Brazil. In these analyses, we have used ratio measures of inequity, rather than absolute or difference measures. For example, if infant mortality rates (IMRs) are equal to 80 deaths per 1000 live births for the poorest subgroup and equal to 20 for the wealthiest, the absolute gap is equal to 60 deaths per 1000, and the rate ratio is equal to four. If, as a consequence of an intervention, the IMR for the poor decreases to 50 and for the wealthy to ten, the difference becomes 40 deaths per thousand—lower than the initial difference—whereas the ratio is now five, greater than the baseline ratio. Difference measures will almost inevitably lead to an apparent reduction in equity gaps, because baseline rates tend to be already low in absolute terms among the wealthiest. Ratio scales, however, take baseline levels into account and are thus more appropriate for deciding whether or not inequity is decreasing. This is consistent with the use of ratio measures in epidemiological research.
The inverse equity hypothesis How can we explain epidemiological trends that show that inequities between rich and poor commonly become worse before showing signs of improving? Figure 1 proposes time trends for hypothetical outcome indicators, such as disease incidence or mortality, in the richest and poorest subgroups in the general population, and presents the corresponding inequity ratios obtained by dividing the level of the outcome in the poor by that in the rich.
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Infant mortality 12 Median to lowest mortality country
10
Brazil to lowest mortality country
8 Ratio
Outcome (log)
Poor
At 1 year the initial inequity in the outcome has a rate ratio of 3·0, which means that the poor are three times worse off than the rich. However, when the new intervention is introduced at year 2 it is initially taken up preferentially by the richer subgroup, as predicted by the “invese equity hypothesis”. A high coverage is rapidly achieved by the rich and by time three the value of their outcome indicator begins to stabilise at a much lower level. A new “minimum achievable level” in morbidity or mortality has been reached at this point and only small further reductions are possible. Between year 3 and 4 inequity, expressed as the rate ratio, widened from 3·0 to about 4·5. At year 4, however, coverage for the interventions starts to increase among the poor, but at a slower rate than it did previously among the rich. At year 5 the inequity ratio or gap has been reduced and it is now back to the original value of 3·0. Scope for further reductions may be greater among the poor, because of their higher initial levels of morbidity or mortality: thus at time six the further improvement in the inequity ratio, now at 2·0, means that equity is now better than at any time since the trends were first seen. The proposed “inverse equity hypothesis” thus attempts to explain why at different times the inequity ratio between rich and poor can improve, remain unchanged, or get worse. Obvously decreases in the inequity ratio suggest that equity is improving. A direct test of this hypothesis is difficult because there are few if any examples of a single health intervention being the sole factor contributing to the decline of a given disease. In real life, multiple interventions are usually present for any single disease and each intervention will have variable coverage levels in different social groups. Given the complexity of real-life trends, whether health inequities increase or decrease will depend on: which
6 4 2 0
1960s
1990s
Child (1-4 year) mortality 12 10 Ratio
100
8 6 4 2 0
1960s 1990s Figure 2: Inequity ratios for national infant and child mortality rates in the Americas11 Source: Pan-American Health Organization.
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PUBLIC HEALTH
effective interventions are available, and for how long and at what quality and coverage—for the wealthy and poor subgroups of the population—since different interventions may vary in their contribution to health improvement in these subgroups; the underlying levels and component causes of disease in these subgroups; and whether or not the rich have already attained the minimum achievable incidence or mortality level with currently available interventions. Taking these variations into account, we examined three case studies that related to recent trends in child health in Brazil.
Inequities in infant and child mortality Information on time trends for IMR and child (1–4 years) mortality rates (IMR) in American countries is based on a Pan-American Health Organization document on mortality trends and initial levels.11 This document showed that both rates had decreased substantially since the 1960s. For this study we estimated inequities in mortality between countries by identifying which country had the median level of infant and child mortality in the Americas, and then dividing these national rates by those for the country with the lowest rate (the USA until 1979 and Canada from 1980 onwards). Figure 2 shows that the median national IMR in the 1960s was 4·5 times higher than for the lowest IMR country, but this inequity ratio increased steadily to reach six in the 1990s. During the same period the ratio between the countries with the highest and lowest IMR had doubled, increasing from about 7 to 14. The interquartile range also increased. For Brazil in the 1960s the IMR was about four times greater than for the lowest mortality country and this ratio doubled to about eight times greater in the 1990s. Thus, although the IMRs had clearly fallen in the Americas, inequities between countries had substantially increased. Child mortality rates (CMR) also fell in the Americas, but the lowest mortality countries seem to have reached a stable minimum level—of about 0·3 per 1000—below which further reductions were likely to be small, given currently available interventions. Contrary to the findings for infant mortality, from the 1960s to 1990s the inequity ratio between the median and lowest child mortality countries in the Americas were nearly halved, falling from about 11 to six times greater. Brazil showed a similar pattern, with the ratio of its CMR to that for the lowest mortality country falling from 12 in the 1960s to five in the 1990s.12 Thus, during 3 decades inequities for child mortality showed an improvement in both the Americas and in Brazil. How does the “inverse equity hypothesis” explain how inequity in the Americas apparently became far worse for infant mortality whereas it improved for child mortality? The results can be interpreted in the light of the hypothetical curves presented in figure 1. Even though infant mortality rates were initially lower in the wealthiest countries, there was still considerable scope for improvement and their rates declined faster than for the intermediate and poorest countries when newly available technologies spread more rapidly in rich countries than in poor countries. Hence the inequity gap increased. For child mortality, however, the richest countries had reached the minimum achievable level much earlier whereas in the poorest countries mortality was still falling in the 1990s. Thus inequity, as measured by CMR ratios, has been reduced, and equity appears to have improved substantially.
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This example does not allow a direct test of the inverse equity hypothesis, since several interventions—as well as economic changes—were taking place simultaneously. Nevertheless, the American example suggests that inequity between countries will tend to be reduced only when the rich nations have reached such low levels that further gains are unlikely.
Inequities in Ceará, northeastern Brazil Evidence that public-health interventions or packages can help in reducing inequities between rich and poor was also sought for the State of Ceará, in the poor northeastern area of Brazil. Early in the 1980s the IMR was above 100 per 1000 and malnutrition was very common. In 1986 the new State government requested UNICEF support to help improve child health and a statewide survey of child health and nutrition was commissioned. More than 4500 childen younger than 3-years old were surveyed by visiting 8000 families in a probability sample of 40 different municipalities.13 Based on the survey conclusions, new health policies were implemented, including the GOBI strategy of growth monitoring, oral rehydration, breastfeeding promotion, immunisation, and vitamin-A supplementation. Since lack of access to health-care facilities was a major problem, a large new programme for community health workers was established and another programme for traditional birth attendants14 was expanded. Responsiblity for health services was decentralised to rural munipalities, which were the ones with the worst health indicators. A social mobilisation campaign for child health was implemented, which included the use of the media and small radio stations to broadcast educational messages. Similar surveys were repeated again in 1990 and 199415 and after each one the results were incorporated into health policy. This process was sustained by four consecutive state governors who all give high priority to improving child health. The experience in Ceará drew international attention and in 1993 the State received the Maurice Pate Award, the annual UNICEF prize for successful progress towards child health and well-being. Considerable advances in the population coverage of the four GOBI interventions from 1987–94 are shown in figure 3. By 1994 the use of oral rehydration solution had increased to more than 50% in children with diarrhoea, nearly all children had a growth chart and a half had been weighed within the previous 3 months, immunisation coverage was 90% or higher, and median breastfeeding duration—a difficult indicator to improve—had apparently increased from 4·0 to 6·9 months. 1987
1994
Measles vaccination Diphtheria toxoid vaccination Use of oral rehydration solution Median time child was breastfed
4·0 months 6·9 months
Ever breastfed Child weighed in past 3 months Growth chart available 0%
20% 40% 60% 80% 100%
Figure 3: Evolution of child-health programme coverage indicators, Ceará State 1987–94
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PUBLIC HEALTH
Indicator
Number of children Percentage of children aged 12–35 months who received all vaccines scheduled for the first year Percentage of children weighed in the 3 months before the survey Percentage of children aged 6–35 months who were breastfed for 6 months or longer Percentage of children with diarrhoea in the previous 2 weeks Percentage of children with diarrhoea who received an oral rehydration solution Percentage of children with weight for age below ⫺2 z scores Percentage of children aged 12 months with length for age below ⫺2 z scores
Year
1987 1994 1987 1994 1987 1994 1987 1994 1987 1994 1987 1994 1987 1994 1987 1994
Family income groups (US$ per month) <60
60–119
120–299
肁300
2026 1207 30 87 24 60 48 52 28 16 19 51 16 12 34 23
1272 609 38 88 31 65 38 49 27 15 26 59 12 8 27 17
619 501 40 93 38 69 36 46 25 13 30 54 8 5 19 10
352 137 44 96 53 69 29 38 19 10 32 47 6 3 9 8
Ratio poor/rich
All children
5·8 8·8 0·68 0·91 0·45 0·87 1·70 1·40 1·50 1·60 0·59 1·10 2·70 4·00 3·80 2·90
4269 2454 35 89 30 64 42 49 26 14 23 54 13 98 28 18
Table 1: Health indicators for children under 3 years of age in the 1987 and 1994 statewide surveys, by income group
Disease frequency and mortality outcome indicators for the whole population also showed considerable improvement between 1987 and 1994. The prevalence of low weight-for-age (below ⫺2 z scores of the National Center for Health Statistics16) fell from 12·7% to 9·2%, low height-for-age from 27·4% to 17·7%, and reported episodes of diarrhoea in children in the previous 2 weeks from 26·1% to 13·6%. Infant mortality was estimated by asking mothers to provide birth histories of children born in the 3 years before the survey. In 1987 the IMR was estimated at 63 per 1000 live births compared with 39 per 1000 in 1994, a 37% reduction. Based on verbal autopsies, diarrhoea proportionate mortality—a priority for the health programme—fell from 48% to 29%, whereas perinatal causes of infant deaths increased from 7% to 21% and respiratory infections from 10% to 25%. Deaths due to other causes, including infections other than diarrhoea and respiratory infections, fell from 35% to 25%. Although these trends in improving population health were clearly substantial, it is important to analyse these trends by richer and poorer socioeconomic subgroups in the whole population. The results in table 1 indicate that the emphasis on reaching the poorest families has been successful in reducing inequity in coverage indicators between the rich and poor. Immunisation rates improved remarkably in all income groups, with the inequity gap between rich and poor closing as the wealthy reached near universal coverage. For both growth monitoring and use of oral rehydration solution, the inequity gap was also narrowed. Assessment of breastfeeding duration showed that in 1987 it was longer among the poorest, whereas by 1994 the gap between rich and poor had now narrowed in favour of the wealthier—an interesting “trickle up” phenomenon, since health messages had been primarily directed to the poorest people. Despite the progress achieved in improving coverage for public-health interventions, inequity between rich and poor for disease frequency and infant mortality remained largely unchanged between 1987 and 1994. The proportions of children in the extreme categories of family income remained almost the same in both years, showing that income inequalities had persisted and remained largely unchanged. Cases of diarrhoea remained about 60% higher among the poor. Possible explanations for the declines seen in both rich and poor groups were increases in breastfeeding duration and in sanitation programmes. Also, the ratio in the prevalence of underweight and stunted children changed only slightly during the period.
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Because of the small number of children in the highest income group in 1994, however, results for this group are hard to interpret. As mortality data stratified by family income were not available, infants deaths during the 3 years before each survey were analysed according to maternal literacy groups. The odds ratios for the IMRs among the infants of illiterate compared with literate mothers were 1·56 (95% CI 1·14–3·01) in 1987 and 2·48 (1·57–3·90) in 1994. Thus, although the overall literacy rate had risen from 82·0% to 86·7%, this overall improvement could not account for the difference seen in the point estimates. In Ceará, despite the implementation of child-health interventions for the poorest families, inequities appeared to remain largely unchanged for four health status impact indicators—weight, stunted growth, prevalence of diarrhoea, and infant mortality. Despite an overall improvement in health, the inequity ratio between rich and poor remained the same. An explanation is that wealthy families had made greater and earlier use of both public sector and private services to protect their children’s health. The conclusions from Ceará suggest that, even with public-health programmes targeted at the poorest, it is difficult to close the inequity ratio group if the rich have not yet achieved high levels of vaccination coverage and consequently low levels of morbidity or mortality. These findings support the predicitons of the “inverse equity hypothesis” that inequity gaps in health status between rich and poor will only be reduced when wealthier families achieve low morbidity and mortality levels, beyond which further progress is difficult—if not impossible—given the current state of public-health interventions.
Inequities in Pelotas, Southern Brazil Good epidemiological evidence from cohort studies done in the city of Pelotas in 1982 and 1993 suggest that inequities can be reduced by public-health programmes. Pelotas is in a relatively developed area in southern Brazil. During 1982 more than 6000 births were studied and this cohort—who are now adolescents—are still being followed up.17 In 1993 another similar birth cohort of 5000 newborn babies was studied.18 Both studies were population based and had high follow-up rates. There was a slight improvement in income distribution during this period (table 2) but wide differentials had persisted. The data analysis used five family income groups, based on the local minimum wage (worth about US$60 during this period). Between 1982 and 1993 there were important changes in health-care delivery in Pelotas and the number of
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PUBLIC HEALTH Indicator
Year
Number of births Percentage of mothers with antenatal care starting before the fifth month of pregnancy Percentage of children with three doses of diphtheria toxoid in first year of life Percentage of children aged 12 months with weight for age below –2 z scores (NCHS) Infant mortality rate (per 1000) Caesarean section rate (%)
Family income groups (US$ per month)
Ratio 肁600
All children poor/rich
60
60–179
180–359
360–599
1982 1993 1982 1993
1321 984 74 84
2837 2166 83 90
1105 1217 93 93
383 437 96 96
336 386 98 97
3·9 2·5 0·76 0·87
1982 1993 1982 1993 1982 1993 1982 1993
72 85 14 9 80 33 19 23
82 89 5 4 34 26 26 25
89 91 1 1 17 10 36 33
94 96 1 0 20 11 43 45
96 94 1 2 13 5 47 56
0·75 0·90 14·0 4·50 6·20 6·60 0·40 0·41
6011* 5304* 85 91 83 90 5 4 36 21 28 31
*Information on family income was missing for 29 and 113 children in 1982 and 1993, respectively.
Table 2: Health indicators in the 1982 and 1993 birth cohorts, by income group, in Pelotas, Brazil
government primary health-care facilities increased from about ten to more than 50. In addition, three neonatal intensive-care units were installed, although such facilities did not serve all the newborn babies in need. There was also an important expansion of government public health and curative programmes. Public-health policies implemented in Pelotas during this period were typical of those commonly adopted in such middle-income countries, with health interventions being made generally available, rather than targeted at the poorest people. Table 2 shows that these changes in health programmes had a substantial effect on inequities as measured by programme coverage. For instance, for both antenatal-care attendance and the take up of immunisations the coverage ratio between rich and poor was reduced as the levels among the poor were raised closer to the high levels already achieved by the rich. Similar improvements in equity, as measured by coverage, were also found for other variables, such as growth monitoring and use of oral rehyration fluids. The prevalence of low weight-for-age at 12 months (below ⫺2 z scores relative to the National Center for Health Statistics16) decreased slightly from 5·4% in 1982 to 3·7% in 1993. Table 3 also shows a large fall from 14% to 9% among the poorest, whereas the three highest income categories remained at between 1% and 2%. Since 2·3% of all children in a well-nourished population would be expected to be underweight, there was little chance of improvement in the three highest income categories. Inequities improved, therefore, largely because the wealthy had already reached a minimum achievable level. Although the IMR fell in Pelotas city from 36 to 21 per 1000 live births between 1982 and 1993, table 2 shows that the mortality rate ratio remained unchanged throughout the decade, with seven times as many poor children dying than wealthy children. To explain why this gap remained, death rates in 1982 and 1993 were stratified according to four combinations of family income and birthweight, a major proximate determinant of infant mortality (table 3). To ensure sufficient sample sizes, families were divided into two groups according to whether income was above or below US$240 a month. Family income group (US$ per month)
<180 肁180
Birthweight (g)
<2500 肁2500 <2500 肁2500
Infant mortality rate (per 1000) 1982
1993
220 25 148 5
141 12 48 5
Percentage 1982–93
36 52 68 0
Table 3: Infant mortality rates in the 1982 and 1993 birth cohorts, by income and birthweight group in Pelotas, Brazil
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The results were striking. There was no improvement in the mortality of wealthy children born with an appropriate birthweight, since their mortality was already at the low level of five per 1000 in 1982, probably the minimum achievable. However, mortality in infants of normal birthweight born into poor families fell by 52%, largely attributable to improvements in the prevention and management of infectious diseases (data not shown). Equity thus improved for infants with appropriate birthweight, with the ratio being halved from 1982 to 1993, from a 5-fold to a 2·4-fold difference. For low-birthweight infants, however, inequities increased substantially throughout the decade. Mortality among these infants fell by 68% for the rich families compared with only 36% among the poor. This was despite the already lower starting level among the richer subgroup since clearly the minimum achievable level had not been achieved in 1982 by either the rich or poor. Thus, the inequity gap increased from 1·5 times in 1982 to 2·9 in 1993. The most likely explanation is that the introduction of new technologies for neonatal intensive care and surfactant therapy were rapidly adopted by the wealthy but were not being accessed to a sufficient coverage level by the poorer families. This explanation was confirmed by the opinions of the neonatologists and obstetricians working in the city’s hospitals and private clinics. It is worth pointing out, however, that not all inequities benefit the rich. Table 2 also shows the rates of caesarean births in Pelotas in 1982 and 1993 by family income groups. Assuming these should not exceed 15% of all deliveries, all income groups in Pelotas were at an increased risk of unnecessary surgery. Women from the wealthiest subgroup in 1993, however were far more likely to have a surgical than a normal vaginal delivery.19,20 Findings on inequity from the Pelotas cohort studies suggest that public-health programmes can improve the health of the poorest children. However, reductions in inequity can be explained by the improvements occurring among the poorer families while the richer ones already had good levels of health. For infant mortality, where reductions for the wealthy were still possible, the inequity gap persisted or even increased, largely because of a combination of improvements in the mortality of appropriate birthweight children balanced against a widening gap in the mortality of low birthweight babies. However, the predictions of the “inverse equity hypothesis” suggest that the infant mortality gap is likely to be reduced in the near future, as the IMR among the poorer families reduces to nearer that of the richer families
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PUBLIC HEALTH
(about five per thousand). The richer subgroup is already at a level found in the world’s lowest mortality countries.21
Conclusion The studies from Ceará and Pelotas suggest that the “inverse equity hypothesis”, a corollary of the “inverse care law” applied to public health, provides a reasonable explanation of several observations. The hypothesis suggests that good quality public-health programmes for improving child health are more available and being utilised by those families who need them least. The hypothesis also predicts that new interventions will tend to increase inequity since they will initially reach those who are already better off. It is only when the wealthy have reached a level of improvement—beyond which publichealth interventions are unlikely to make more progress— that the poor begin to catch up and the inequity gap begins to improve. Thus, only over time will the gap be narrowed. The timing factor is therefore essential in the interpretation of the equity impact of new technologies. Unfortunately, the analysis and interpretation of time trend data for inequities is made more complex by the act that many new health interventions are being introduced all the time. As was shown for infant mortality in Pelotas, it is only when interventions have had their maximum impact on the wealthy groups that the inequity gap with the poor begins to improve. However, mortality among the rich is now being further reduced by new perinatal interventions that have yet to fully reach the poor. In addition, morbidity and mortality levels obviously can be prevented from deteriorating. However, they also depend on concomitant changes in socioeconomic, demographic, and environmental factors—factors that also interact with the public-health interventions themselves. In the case of Ceará and Pelotas there is no reason to believe that slower progress among the poor was due to a deterioration in their standard of living. On the contrary, during the study period in Ceará there was a substantial reduction in fertility and some socioeconomic improvement, as well as progress in sanitation and health care,22 and in Pelotas the stake of the poorest improved between the two birth cohorts.23 The persistence of the inequity gaps should not be attributed, therefore, to a deterioration in non-health-sector factors affecting health status, but to the fact that an increasing proportion of the rich were making use of newer technologies that were still unavailable to most of the poor. The conclusions as to whether public-health programmes can impact on inequities appears to be both optimistic and pessimistic. The optimistic conclusions are that, first, to raise programme coverage levels among both rich and poor is possible and, second, that inequities in morbidity and mortality rates may improve given time. The other good news is that health indicators seem to be improving for all social groups and should continue to do so in the future if the availability of social programmes is not curtailed by political or economic crises. In absolute terms, therefore, fewer and fewer children are being adversely affected in all social groups. The pessimistic conclusion is that public-health programmes specifically targeted towards the poorest— such as in Ceará—may not succeed in closing the overall gap in child health within a reasonable time period. However, such programmes may perhaps prevent the inequities from deteriorating even further. We would argue that investment in public-health interventions is a priority in order to prevent inequities
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becoming worse among poor people in the developing world. This is particularly true given the current global trends toward neoliberalism and a reduced state role in financing the health sector. In most less-developed societies, the wealthiest are likely to continue to benefit from the introduction of new health technologies. Unless investment is also made to make existing and new interventions more widely accessible to the poorest, inequity gaps may widen rather than be reduced. Data on mortality trends in the Americas were kindly provided by J A Casas and J N Dachs from the Pan-American Health Organization. The Pelotas studies were financed by IDRC, ODA (now DfID), and the European Commission. The Ceará surveys were funded by UNICEF and by the State Government. We thank other members of the research team Francisca Maria Andrade, Luciano Correa, and Jay MacAuliffe.
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