Urine testing for isoniazid in the supervision of out-patient oral chemotherapy for pulmonary tuberculosis. The failure of a routine service.

Testing urine specimens obtained at surprise visits to the home or at routine clinic attendance is an established procedure in the supervision of patients receiving ambulatory chemotherapy for pulmonary tuberculosis. A urine test service was set up in 9 East African centres, involving 37 staff members (most with limited training) who conducted a simple paper test for isoniazid. Analysis of the results obtained yielded an unbelievably high proportion of positive results, indicating that the testing system, as organized, had been a failure. Special investigations were therefore carried out into the reasons for this.Over-reading of test results, incorrect performance of the test, and, in 1 centre, dishonest recording were found as explanations. Discussing the implications of their findings, the authors stress the importance of close supervision at all stages of tuberculosis-control procedures in the field, no matter how simple; and they point out with reference to urine testing that, even if a centralized testing system, involving a sensitive test method and quality control, were to be set up in regional laboratories, adequate supervision at all stages would be essential.