Urine metabolite-determined isoniazid adherence under programmatic conditions in people living with HIV

BACKGROUND Chemotherapy to prevent TB is a core component of care for persons living with HIV (PLHIV). There are few reports describing adherence to TB prevention under programmatic conditions in high TB burden settings. METHODS We measured adherence to daily isoniazid (INH) preventive treatment (IPT) using a commercially available colourimetric assay to detect urine INH metabolites among PLHIV who self-reported INH ingestion within the preceding 24 h. Enrollee characteristics associated with non-adherence despite self-reported INH ingestion were identified in multivariate log-binomial regression. Interoperator reliability for the detection of INH metabolites was calculated among three independent operators. RESULTS Self-reported INH ingestion and metabolite data were known for 300 PLHIV. INH metabolite was detected in 112 (68.7%) of 163 PLHIV who self-reported INH ingestion in the preceding 24 h. The prevalence of alcohol consumption was significantly higher among INH-non-adherent PLHIV compared with INH-adherent PLHIV (adjusted prevalence ratio 2.43, 95% CI 1.16-5.12). Two-way interoperator reliability ranged from κ 0.86 to κ 0.94. CONCLUSIONS Compared with self-reported 24-h INH ingestion in a high TB-HIV-incidence programmatic setting, biometric adherence to IPT was suboptimal in this sample of PLHIV. Alcohol consumption was the only potentially modifiable risk factor significantly associated with INH non-adherence. Colourimetric interpretation reliability across three operators was moderate/strong. .