The potential of the case-control method for rapid epidemiological assessment.

ABSTRACT

Over the past few decades, the case-control method has been mostly applied to risk-factor studies of chronic diseases. Recently, among its new applications is the use of the method to study the health effect of improvements in sanitation and water supply. The methodological considerations, prospects and constraints of the method for rapid assessment are reviewed.

ABSTRACT

PIP It has been proposed that case-control studies be used to evaluate the health impact of sanitation and water supply improvement programs upon diarrheal disease. Experimental and still in need of field studies for further substantiation, methodological considerations, prospects, and constraints of this rapid assessment method are reviewed. Drawing from a clinic-based case-control study in Cebu, a peri-urban area of the Philippines, the paper discusses the issues of methodological approach, study site, study period, sample size, potential sources of bias, and comparing findings from field studies. Case-control studies have the advantages of requiring only a single round of data collection over a short period, while yielding better quality information on disease status. This approach also avoids some ethical problems associated with quasi-experimental designs. These studies do not, however, permit examination of the effect of exposure upon more than 1 outcome, and are inappropriate for situations in which exposure is rare. Case-control studies are also highly vulnerable to bias. In closing, the paper concludes that this method could save time and money over prospective designs in rapid assessment without sacrificing a study's integrity. Case-control studies are, nonetheless, complicated with heavy demands for trained manpower and logistical support. Accordingly, they are presently best suited for urban areas. Steps toward procedural and method design simplification are needed, with care taken to safeguard the method's quality and applicability.