The reliability of retrospective studies using a one-year recall period to measure dracunculiasis prevalence in Ghana.

BACKGROUND

Cross-sectional studies are usually adopted to assess the one-year period prevalence of dracunculiasis. They depend upon a recall period of up to one year. This paper aims to examine the degree of accuracy with which villagers in an endemic region recall the occurrence of dracunculiasis during the 12 months prior to a cross-sectional survey.

METHODS

Two types of study were conducted in Tolon, a village in Northern Ghana--retrospective and prospective. Data from people interviewed in a bimonthly survey throughout 1990 were compared with the results of a cross-sectional retrospective study conducted in early 1991.

RESULTS

The results showed that retrospective studies using a recall period of up to one year to measure dracunculiasis prevalence gave only 59.9% of the actual cases, but there were roughly equal numbers of 'false positive' and 'false negative' cases, so that overall prevalence obtained was very close to the correct figure.

CONCLUSIONS

Cross-sectional surveys may be of use to obtain estimates of the one-year period prevalence of dracunculiasis, but are not likely to be reliable enough for more detailed study.