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Int J Epidemiol. 1998 Aug;27(4):672-6.

Comparison of key informant and survey methods for ascertainment of childhood epilepsy in West Bengal, India.

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Neurosciences Unit, Institute of Child Health, University College London, UK.



This study aimed to compare efficacy and cost of key informants and survey for ascertainment of childhood epilepsy within a treatment context in rural India.


The study was set in a non-governmental, community programme for the functional and socioeconomic rehabilitation of children with disabilities in rural West Bengal, India. Ascertainment was by two methods: house-to-house survey of 15000 households and also by 430 key informants including village leaders, health workers and 670 schoolchildren. Methods were compared for positive predictive value, and sensitivity by capture-recapture technique. Ninety four children were enrolled into treatment. Predictors of treatment success were determined by multiple logistic regression analysis, giving adjusted odds ratios for remission. The costs of identifying one case and one treatment success were measured by costing personnel, materials and overheads.


The survey was four times as sensitive as key informants although the positive predictive values were similar (36%, 40%). The survey had an absolute sensitivity of only 59%. Identification by key informants strongly predicted successful treatment outcome (odds ratio [OR] = 4.74, 95% confidence interval [CI] : 1.19-18.85). The cost of finding one case was US$11 and US$14, and of finding one successful treatment outcome US$35 and US$67 for informants and survey respectively. Key informants were essential in attaining longer term programme objectives.


In the context of a treatment programme, key informants were the more cost-effective method, but community involvement was traded against low sensitivity in the short term. Overall ascertainment costs were significant in the context of primary health care in India.


Epilepsy is the most important neurological problem in developing countries, with a total of 50 million people worldwide having the condition. 33 million of these cases are children in developing countries, of whom 90% are untreated. To determine the number of children with active epilepsy in a given developing country community, previous studies have either ascertained information directly from key informants in the community or through more broad-based two-stage surveys. Findings are reported from a study conducted in 46 villages of district 24 Parganas South, a rural district south of Calcutta, comparing the two approaches' sensitivity, efficacy, and costs. Village leaders, health workers, and students were interviewed as key informants, while house-to-house surveys were conducted in 15,000 households. The survey was 4 times as sensitive as the key informant approach, although the approaches had similar positive predictive values. The survey had an absolute sensitivity of 59%. Case identification by key informants strongly predicted successful treatment outcomes. The cost of finding 1 case was US$11 and US$14, and of finding one successful treatment outcome US$35 and US$67 for informants and survey, respectively. The use of key informants was essential to attaining longer-term program objectives.

[Indexed for MEDLINE]

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