- Email: [email protected]
Life expectancy in Seychelles
Correspondence
Life expectancy in Seychelles Joshua Salomon and colleagues’ study (Dec 15, p 2144)1 represents a monumental effort of gathering data, and provides unparalleled information on progress of life expectancy worldwide. However, life expectancy at birth for Seychelles is reported to have decreased from 62·0 years to 61·3 years for men, and from 72·4 years to 71·8 years for women between 1990 and 2010 (table 2 and figure 3):1 this is inaccurate. Based on census and vital statistics data, life expectancy at birth in Seychelles increased from 63 years to 69 years in men, and from 74 years to 79 years in women, between 1990 and 2010. When pooling data over several years (eg, 1989–91 vs 2009–11), in view of the small size of the population of Seychelles, the magnitude of these values and trends over time is similar. Obviously, data for healthy life expectancy presented in Salomon and colleagues’ report should also be corrected accordingly. Seychelles is one of the very few countries in Africa where the entire population is enumerated through regular censuses (last in 2010) with yearly updates done by civil authorities between censuses, and where all deaths are registered (and 90
an electronic database maintained) for more than two decades. Therefore, accurate life expectancy can be straightforwardly and accurately calculated in the Seychelles, and figures have been reported on government websites, in official reports, and in several scientific papers on the epidemiological situation in Seychelles (figure). The large increase in life expectancy during the past two decades in Seychelles is consistent with marked socioeconomic development during the interval, fairly moderate HIV epidemic compared to other countries in the region, and the progressive health policy including free access to health care for all individuals. More specifically, age-adjusted mortality decreased by as much as 30% between 1990 and 2010,2 consistent with a decreased prevalence of some major risk factors, such as tobacco use.3 The discrepancy between life expectancy reported by Salomon and colleagues and actual figures in Seychelles raises issues on the accuracy of estimates provided in the paper and the channels through which data are gathered, admittedly a main challenge in large international studies. We declare that we have no conflicts of interest.
*Pascal Bovet, Jude Gedeon [email protected]
Women Men
Life expectancy (years)
80
70
60
50 1975
1980
1985
1990
Year
1995
Figure: Life expectancy at birth in Seychelles between 1976 and 2012
www.thelancet.com Vol 382 July 6, 2013
2000
2005
2010
University Institute of Social and Preventive Medicine, Lausanne 1005, Switzerland (PB); and Ministry of Health, Seychelles (JG) 1
2
3
Salomon JA, Wang H, Freeman MK, et al. Healthy life expectancy for 187 countries, 1990–2010: a systematic analysis for the Global Burden Disease Study 2010. Lancet 2012; 380: 2144–62. Stringhini S, Sinon F, Didon J, Gedeon J, Paccaud F, Bovet P. Declining stroke and myocardial infarction mortality between 1989 and 2010 in a country of the African region. Stroke 2012; 43: 2283–88. Bovet P, Romain S, Shamlaye C, et al. Divergent 15-year trends in traditional and metabolic risk factors of cardiovascular diseases in the Seychelles. Cardiovasc Diabetol 2009; 8: 34.
Authors’ reply The Global Burden of Disease 2010 study1 relied on population estimates by age and sex from the World Population Prospects 2010 revision, the Human Mortality Database, and the WHO mortality database. All these data sources are restricted to populations that meet a certain threshold in terms of size, and none of them provide age-specific and sexspecific estimates for Seychelles. We also conducted an extensive search for other available sources, but did not find a suitable source for age-specific and sex-specific population estimates for years 1970–2010 for Seychelles. We used total population estimates for Seychelles (1950–2010) from the US Census Bureau, and applied the regional average age-sex distribution using data from the UN Population Division. Our estimated population structures were indeed different from those referenced by Pascal Bovet and Jude Gedeon because we were not aware of, and did not have access to, the annual reports on deaths and population from the Management and Information Systems Division within the Government of Seychelles. The differences in population estimates by age and sex are consequential for estimates of age-specific and sex-specific mortality rates, as they constitute the denominators for the mortality estimates, and differences in mortality by age and sex in turn drive estimates of life expectancy
Submissions should be made via our electronic submission system at http://ees.elsevier.com/ thelancet/
23
Life expectancy in Seychelles Joshua Salomon and colleagues’ study (Dec 15, p 2144)1 represents a monumental effort of gathering data, and provides unparalleled information on progress of life expectancy worldwide. However, life expectancy at birth for Seychelles is reported to have decreased from 62·0 years to 61·3 years for men, and from 72·4 years to 71·8 years for women between 1990 and 2010 (table 2 and figure 3):1 this is inaccurate. Based on census and vital statistics data, life expectancy at birth in Seychelles increased from 63 years to 69 years in men, and from 74 years to 79 years in women, between 1990 and 2010. When pooling data over several years (eg, 1989–91 vs 2009–11), in view of the small size of the population of Seychelles, the magnitude of these values and trends over time is similar. Obviously, data for healthy life expectancy presented in Salomon and colleagues’ report should also be corrected accordingly. Seychelles is one of the very few countries in Africa where the entire population is enumerated through regular censuses (last in 2010) with yearly updates done by civil authorities between censuses, and where all deaths are registered (and 90
an electronic database maintained) for more than two decades. Therefore, accurate life expectancy can be straightforwardly and accurately calculated in the Seychelles, and figures have been reported on government websites, in official reports, and in several scientific papers on the epidemiological situation in Seychelles (figure). The large increase in life expectancy during the past two decades in Seychelles is consistent with marked socioeconomic development during the interval, fairly moderate HIV epidemic compared to other countries in the region, and the progressive health policy including free access to health care for all individuals. More specifically, age-adjusted mortality decreased by as much as 30% between 1990 and 2010,2 consistent with a decreased prevalence of some major risk factors, such as tobacco use.3 The discrepancy between life expectancy reported by Salomon and colleagues and actual figures in Seychelles raises issues on the accuracy of estimates provided in the paper and the channels through which data are gathered, admittedly a main challenge in large international studies. We declare that we have no conflicts of interest.
*Pascal Bovet, Jude Gedeon [email protected]
Women Men
Life expectancy (years)
80
70
60
50 1975
1980
1985
1990
Year
1995
Figure: Life expectancy at birth in Seychelles between 1976 and 2012
www.thelancet.com Vol 382 July 6, 2013
2000
2005
2010
University Institute of Social and Preventive Medicine, Lausanne 1005, Switzerland (PB); and Ministry of Health, Seychelles (JG) 1
2
3
Salomon JA, Wang H, Freeman MK, et al. Healthy life expectancy for 187 countries, 1990–2010: a systematic analysis for the Global Burden Disease Study 2010. Lancet 2012; 380: 2144–62. Stringhini S, Sinon F, Didon J, Gedeon J, Paccaud F, Bovet P. Declining stroke and myocardial infarction mortality between 1989 and 2010 in a country of the African region. Stroke 2012; 43: 2283–88. Bovet P, Romain S, Shamlaye C, et al. Divergent 15-year trends in traditional and metabolic risk factors of cardiovascular diseases in the Seychelles. Cardiovasc Diabetol 2009; 8: 34.
Authors’ reply The Global Burden of Disease 2010 study1 relied on population estimates by age and sex from the World Population Prospects 2010 revision, the Human Mortality Database, and the WHO mortality database. All these data sources are restricted to populations that meet a certain threshold in terms of size, and none of them provide age-specific and sexspecific estimates for Seychelles. We also conducted an extensive search for other available sources, but did not find a suitable source for age-specific and sex-specific population estimates for years 1970–2010 for Seychelles. We used total population estimates for Seychelles (1950–2010) from the US Census Bureau, and applied the regional average age-sex distribution using data from the UN Population Division. Our estimated population structures were indeed different from those referenced by Pascal Bovet and Jude Gedeon because we were not aware of, and did not have access to, the annual reports on deaths and population from the Management and Information Systems Division within the Government of Seychelles. The differences in population estimates by age and sex are consequential for estimates of age-specific and sex-specific mortality rates, as they constitute the denominators for the mortality estimates, and differences in mortality by age and sex in turn drive estimates of life expectancy
Submissions should be made via our electronic submission system at http://ees.elsevier.com/ thelancet/
23