Urine testing to monitor adherence to TB preventive therapy

This study examined the validity of the Arkansas urine test. One hundred ninety-four adolescents submitted an unannounced urine specimen monthly (for 6 to 8 months). Duplicate specimens were blindly tested with high agreement (kappa >90%). Sensitivity and specificity were estimated. In 68% of test runs, adolescents recalled taking INH within 24 hr of specimen collection. For recall intervals of 24, 48, and 72 hr, sensitivity was 87, 85, and 83%, respectively. Females were less likely to test positive when INH was taken within the previous 24 hr (sensitivity 84 versus 92% males). Specificity was 57, 91, and 95% at 24, 48, and 72 hr, respectively. The Arkansas urine test was practical to use, and results correlated well with self-reported adherence to INH for treatment of latent tuberculosis infection (LTBI), over several months of follow-up. The test may be useful as part of an adherence-monitoring program when used in conjunction with self-reported measures.