Morbidity measurement in household surveys in developing areas

SW. %I & Med.. Vol 13D. pp. 223 to 226 c Pergamon Press Lid 1‘479. PrInted m Greal Bntam

MORBIDITY MEASUREMENT IN HOUSEHOLD SURVEYS IN DEVELOPING AREAS WILBERT M. GESLER Department of Geography, Rutgers College. 185 College Ave. New Brunswick, NJ 08903, U.S.A. Abstract-The accuracy of morbidity measurement in household surveys in developing areas is affected by various local constraints. This report discusses an attempt to meet the constraints imposed on the illness section of a sarvey conducted in the target area of the Family Health Clinic in Calabar, Nigeria. A list of symptoms was drawn up to elicit data on the illnesses mothers and their children under six experienced in a 2-week period. Several criteria were kept in mind when constructing this list. It was recognized that both interviewers and respondents had relatively low levels of education. It was also felt that responses should rdlect both local morbidity patterns and ailments commonly treated at the Ftimily Health Clinic. Anotha criterion was that the data should be suitable for statistical testing. Following the survey. the symptoms were classified under the headings of general, digestive, and respiratory. The illness item in the survey questionnaire was checked for reliability and validity.

In all regions of the world health care planners require information about the morbidity status of target populations. This information includes the prevalence of specific diseases, illness severity, and disability due to illness. Data may be obtained from records kept by doctors, clinics, and hospitals, or from household surveys. The quality of the information is restricted by such constraints as the competency of record keepers or interviewers, time and cost limitations, and local perceptions about particular disease states. These constraints are more serious in developing areas. In the case of household surveys the need arises to construct questionnaire items that meet local constraints and also produce results that are both reliable and valid. This report deals with the construction and field testing of the illness section of a health care delivery questionnaire administered to a sample of children under six and their mothers Hjho resided in the target area of the Family Health Clinic in Calabar, Nigeria. The clinic is run by the Institute of Child Health of the University of Lagos and provides preventive and curative care for women and children. Client records provided by medical institutions are the most accurate source of morbidity data. However, this information does not cover the entire target population. Furthermore, medical diagnosis is expensive, rakes a great amount of organization, and requires medical personnel, a scarce commodity in developing areas. Household surveys on the other hand can cover a representative sample of people in service areas. They are relatively inexpensive, fairly easy to conduct, generally have higher response rates than examination techniques, and can be administered by non-medical personnel. Their principal drawback is their dubious accuracy. Comparisons of household survey results with clinical diagnoses reveal serious discrepancies in proportions of the population studied who were reported or diagnosed to be suffering from certain ailments [l]. Several types of classification scheme can be used to aggregate symptoms or diagnoses reported from

surveys. All suffer from problems of co-existing conditions, the intangible nature of many disease characteristics, and different uses for the same measure. The most commonly used schemes depend on some form of disease categorization such as the International Classification of Diseases [2,3]. Such categorizations are useful for allocating resources to deal with groups of disease conditions. However, they are mainly anatomical and thus the same complaints may stem from different etiologic agents. Also, they do not establish levels of disability or severity. CONSTRUCTIONOF THE MORBIDITYSCHEDULE

The Calabar questionnaire was drawn up after discussions with health personnel in the city and following a pre-test of items in non-sample areas of the clinic target area. It was decided that questions regarding illness would be guided by these considerations: (1) The questionnaire would be administered by Field Health Workers from the clinic staff who all had a primary school education and some instruction in good health practices, but who could not be expected to diagnose illness during interviews. (2) The respondents were not all literate and most would be unfamiliar with western medical terminology. (3) The items should reflect what was known about local morbidity patterns. (4) The items should reflect the major types of illness treated by the Family Health Clinic so results could be incorporated into their health care plans. (5) The data collected would be used in statistical analyses. The first major decision was to deal with symptoms rather than diagnostic terms in the questionnaire. This clearly follows from the criteria of understanding by interviewees and ease of administration by interviewers. In addition. the pre-test showed that the Field Health Workers had difficulty classifying illnesses under such headings as “gastro-intestinal” or “upper respiratory”. Therefore the matter of diagnostic classification was dealt with when the results were analyzed. The interviewers also could not distinguish. 223

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among spontaneously produced reports of illness, reports probed for, and illness observed, so this classification, which a study in India found useful [4] was not pursued further. The next consideration was the specific items to include in the list of symptoms read out to mothers [S]. This list followed the question, “What were the .symptoms of the illness (name of person for whom illness was reported) had during the last 2 weeks?” Four sources were tapped to establish a list of symptoms that both health personnel and lay people felt were the most common symptoms in Calabar. First, a tentative list was drawn up based on: (1) a lecture given by the clinic matron to the Field Health Workers before the pre-test on symptoms to look for in women and children. (2) Symptoms the clinic nuris said were most commonly reported by their clients. (3) The complaints reported on the openended illness item used in the pre-test schedule. Most of the symptoms on this list grouped around three major categories of illness, gastro-intestinal, respiratory and malarial. To simplify the analysis, all symptoms not related to the three categories just mentioned were not included in the questionnaire. Illnesses such as measles, although they were extremely important in Calabar, were left out because they did not occur frequently enough to be used in statistical tests. Skin problems were left off the list as’ they are relatively long-term and often are treated secondarily to the three major types of illness at the clinic. Thus a complete morbidity profile of the target population was sacrificed to satisfy the criteria set forth above. The fourth input to the symptoms list came from a class of 10 student nurses at the College of Health Technology in Calabar, all of whom had spent several years in practical nursing. They were asked to list the most common symptoms reported in association with gastro-intestinal, respiratory, and malarial illnesses. If a symptom was listed by at least three nurses, it was included in the questionnaire. Three additional symtoms, “internal heat” (a common but little understood complaint), “sore throat”, and “constipation” were added as well because they were consistently reported by the sources used to draw up the first symptom list. The final list of symptoms contained 23 items (Table 1). These were translated into Efik/Ibibio, the language spoken by the majority of Calabarians, by Table 1. Symptoms General Fever Weakness Fretful Chills Sweating Thirsty/dry lips Cannot sleep Convulsions Pain in joints Ache all over Internal heat

one of the Field Health Workers. The other interviewers and the clinic matron reviewed the list to make sure that the translations were correct and that the Efik/Ibibio terms were in common use in the city. Data were collected on 444 children and 260 mothers during the survey. With only two exceptions. mothers answered for themselves and their children. For the most part, information gathered on the children will be used for illustrative purposes.

The Field Health Workers simply checked off all symptoms a mother mentioned in connection with an illness. An attempt was made to group symptoms into separate illness episodes on the basis of practitioner contacts made for different clusters of symptoms. There was only one report of a child who had two distinct episodes, treated separately, however. Either women usually went to practitioners to seek help for all symptoms or the interviewers failed to separate distinct episodes. Interviewers recorded the date each symptom began and ended. A calendar covering the survey period was printed on the questionnaire to aid them in this task. The information was used to calculate illness duration, a measure of severity. SYMPTOM

CLASSIFICATION

To classify the symptoms on the basis of standards in the health field, as many of them as possible were placed under categories established by the National Center for Health Statistics manual, The used

National Ambulatory Medical Care Survey: Sympton Classijcation (Table 1) [6]. Using this publication as

a guide, “fever”, “weakness”, “fretful”, “chills”, “sweating”, “thirsty/dry lips” and “ache all over” were placed under the general heading; “frequent or loose stools”, “vomiting”, “loss of appetite”, “stomach pain”, “stomach distended”, “sore throat” and “constipation” were placed under the digestive heading; and “runny nose”, “cough”. “difficult breathing”, “chest pain” and “side pain” were placed under the respiratory heading. Three symptoms were placed under general that the NCHS manual classifies under other headings to keep the categories to a minimum. These symptoms were: “cannot sleep” and “convulsions” (nervous in the manual) and “pain in joints” (musculoskeletal in the manual). The symptom “internal heat” was also termed general. The general category included symptoms such as “fever” and “ache all

from the household categories* Digestive Loss of appetite Vomiting Stomach pain Frequent or loose stools Stomach distended Sore throat Constipation

survey placed

into illness

Respiratory Runny nose Cough Difficult breathing Chest pain Side pain

* Symptoms are listed in the order most often reported by student nurses

Morbidity measurement Table 2. Proportions

of childhood

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in household surveys

diseases reported

in survey and treated at clinic

during the survey period Illness category Case source

General

Digestive

Respiratory

Total

48 39.0

23 18.7

52 42.3

123 100.0

116 31.2

69 18.5

187 50.3

372 100.0

Survey report

Number of cases Percent of cases Clinic treatment

Number of cases Percent of cases x2 = 2.94, P > 0.20.

over” which respondents generally associated with malaria, although malaria may not. have been present. This disease is endemic in the area, however, and one suspects that it made up a large proportion of general cases. Thus three broad categories that were relevant to clinic practice were established. Each contained enough cases for statistical tests to be conducted using morbidity information. For example, subgroups of the population (based on demographic, socioeconomic, and environmental characteristics) were compared in terms of their experience of the three types of illness [7]. If more than one symptom was reported for an illness, a decision had to made about which category best applied to that episode (unless they all fell in the same category). The following guidelines were used in these situations: (1) Digestive and respiratory symptoms always took precedence over general ones as they were deemed more important. (2) Symptoms that appeared earlier took precedence because it was felt that they were likely to have led to subsequent symptoms. (3) If two symptoms began at the same time, then the one that lasted.longer took precedence. (4) If two symptoms began at the same time and had the same duration, the symptom that ranked higher in the student nurses’ lists took precedence. The survey reported out 123 illnesses for children under six. Guideline (1) was often invoked but the other three which involved only digestive and guidelines, respiratory illnesses, were used in only three cases. RELIABILITY

AND

VALIDITY

Re-interviews were conducted on approximately 8”/, of the interviewees the day following the initial interview. The symptom data was checked for five of the 68 ill mothers and 11 of the 123 ill children. Only nine of there-interviews produced reports of exactly the same symptoms from one day to the next. In four of the seven cases where there was lack of agreement, some of the symptoms reported were the same. For example, a mother reported “cough” one day and both “cough” and “fever” the next day. Category reporting showed far better reliability than symptom reporting; in 13 out of the 16 cases illness fell into the same category in both interview and re-interview. Some of the following aspects of the re-interview situation might have influenced its results: (1) Whereas the interview was conducted by a Field Health Worker well known to respondents. the re-

interview was not. (2) The researcher was present at most of the re-interviews. (3) Illnesses can change their course from day to day. (4) There were problems of recall in reporting symptoms. Proportions of children falling into the three illness categories were compared with proportions of children treated at the clinic for the same types of ailments during the survey period (Table 2). The clinic treated a slightly smaller proportion of general cases than were found in the sample population, slightly more respiratory cases, and the same proportion of digestive cases. This validity check is not very satisfactory as it assumes that the clinic treated illness types in proportion to their occurrence in the population. DISCUSSION

The method of measuring morbidity discussed here is clearly not a sophisticated one. It cannot pretend to be as reliable and valid as clinical diagnoses. It does not distinguish well between distinct episodes and does not produce a detailed history of illness. The method does satisfy the criteria outlined above. The symptom question was stated in a very simple manner in language that interviewers and interviewees understood and used in everyday speech. Clinic nurses use the same terms when they deal with mothers and children. The Field Health Workers were not required to make diagnoses. They did have the advantage of knowing the area and their clients. It is true that the survey did not present a complete picture of the morbidity status of the target population. It could easily be expanded, however,-to include such illnesses as measles. Problems that are not easily detectable by non-medical intervieweh could be investigated using means other than survey questions. Malnutrition, for example, can be fairly accurately measured using an arm band. One of the most important aspects of this survey was that a wide variety of local people, both health professionals and laymen, participated in the selection of specific items to be used. The items chosen cover the majority of illnesses both experienced by the target population and treated at the Family Health Clinic. Stress was laid not on comparability of morbidity in different populations, but on integration of the survey with local clinic practice. Any survey drawn up along these lines could easily be adapted’to other local situations. As in other morbidity studies, the categorization scheme was based on an accepted classification, modi-

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fied to conform to local practice. A set of classification rules based on severity, importance to clinic

nurses, and symptom precedence in time, was established in an attempt to solve the problem of complex disease syndrome classification. Only a few categories were established so that the data could be entered into statistical tests. Individual symptom reliability was not encouraging but category reliability was. Since categories are what is important to the clinic and to study analyses, one can conclude that in this small-scale study reliability was good. A better procedure than the simple one used here would be necessary to adequately test the validity of surveys of this type. REFERENCES 1. Belcher D. W. Neumann A. K., Wurapa F. K. and Lourie I. M. Comparison of morbidity interviews with

2. 3. 4.

5.

6. 7.

a health examination survey in rural Africa. Am. J. trop. Med. Hyg. 25, 751-758. 1976. Nchinda T. C. A household study of illness prevalence and health care preferences in a rural district of Cameroon. fnt. J. Epidem. 6, 235-241. 1977. Bridges-Webb C. et al. The Australian general practice morbidity and prescribing survey. 1969 to 1974. Med. J. Aust. Special Suppl. 528, 1976. Functional Analysis of Punjab Health Services. Directorate of Health and Family Planning. Chandigarh, Punjab, 1972. Reading such a list to respondents was suggested by the investigators in the Danfa, Ghana. survey. Belcher D. W., Wurapa F. K., Neumann A. K. and Lourie 1. M. A household morbidity survey in rural Africa. !nt. J. Epidem. 5, 113120, 1976. National Center for Health Statistics, Department of Health, Education and Welfare, Rockville, MD, 1974. Gesler W. Illness and Health Practitioner Use in Calabar, Nigeria. Sot. Sci. Med. 13D. 23-30, 1979.