The value of urine testing for verifying adherence to anti-tuberculosis chemotherapy in children and adults in Uganda

SETTING: Mulago Hospital, Kampala, Uganda. OBJECTIVE: To evaluate the usefulness of urine dipsticks for monitoring adherence to anti-tuberculosis chemotherapy. DESIGN: In-house urine dipsticks for detection of isoniazid (INH) metabolites were compared to commercial test strips. The value of n-butanol to detect rifampicin was compared to coloration of the urine. Non-adherence was assessed through a questionnaire and reviews of the Mulago Hospital TB register. RESULTS: Urine was obtained from 236 patients (127 adults and 109 children) on daily chemotherapy. Using commercial test strips as standard, the sensitivity of in-house urine dipsticks was 99.5% and specificity was 96.4%. The sensitivity and the specificity of n-butanol and of coloration of urine to detect rifampicin were low (64.0% and 54.9%, and 85.5% and 64.8%, respectively). Fifty patients (21.2%) admitted non-adherence to treatment during the previous month. An additional 15 (6.8%) were detected through urine testing. Of 911 patients in the TB register of Mulago Hospital who had started treatment in the first 3 months of 2000, 39.7% did not complete their treatment. Two-thirds of these had discontinued treatment in the first 2 months. CONCLUSION: In-house INH test strips are as effective as commercially available strips for detecting isoniazid in the urine. They are a simple tool for monitoring adherence. Adherence to anti-tuberculosis chemotherapy as determined by the use of isoniazid test strips and review of the TB register showed poor compliance. Tests for rifampicin are less sensitive and specific.