Enumeration of non-communicable disease in rural South Africa by electronic data linkage and capture-recapture techniques

Non-communicable diseases (NCDs) are becoming increasingly common and impor tant in developing countries, yet their enumeration is problematic. We have attempted to enumerate NCD patients in a rural district of KwazuluNatal, S outh Africa, using the techniques of electronic data linkage and capture-re capture (CR). We examined four major NCDs (hypertension, diabetes, asthma a nd epilepsy). Basic patient details were recorded onto EpiInfo software ove r a ti-week period, from the main hospital clinic at Hlabisa, as well as th e 10 outlying peripheral health clinics. Using electronic data linkage of l ists from the main hospital, the peripheral clinics, and repeat prescriptio n cards, a district NCD register was produced of 2455 patients. The mean ag e was 51 +/- 16 years (1 SD) and 76% were female. Of the total NCD patients , 62% had hypertension (age 57 +/- 12 years, 82% female), 16% epilepsy (age 35 +/- 17 years, 49% female), 13% asthma (age 45 +/- 19 years, 60% female) and 12% diabetes (age 54 +/- 13 years, 61% female). Estimated population c rude prevalence rates for known NCD cases on the register were 7.4% for hyp ertension, epilepsy 0.2%, asthma 0.2% and diabetes 0.2%. We also attempted a CR analysis to assess completeness of data, by comparing overlap between patients attending peripheral clinics, and the central Hlabisa Hospital cli nic. Matching by name, age, and diagnosis proved feasible, but there was li ttle overlap, and CR calculations were invalid because of the relative inde pendence of sources. We conclude that NCDs are common in rural Africa, and that a simple NCD district register is a potentially feasible and inexpensi ve option. Capture-recapture analysis is feasible, but requires suitable li sts with acceptable overlap of patients.