To dose-adjust or not to dose-adjust: 3TC dose in kidney impairment.

OBJECTIVES To assess the risk of adverse diagnoses and laboratory abnormalities associated with a 300 mg or 150 mg daily dose of 3TC initiated by people living with HIV (PLWH) with an estimated glomerular filtration rate (eGFR) between ≥30 and ≤49 ml/min/1.73m2. DESIGN Longitudinal study based on electronic health records of 539 PLWH with eGFR between ≥30 and ≤49 ml/min/1.73m2 from the Observational Pharmaco-Epidemiology Research and Analysis (OPERA®) cohort. METHODS Common unintended effects of 3TC were evaluated as composite outcomes. We estimated the incidence (univariate Poisson regression) and association between dose and incident composite outcomes (multivariate Poisson regression) among PLWH without the relevant diagnoses or laboratory abnormalities at 3TC initiation. RESULTS PLWH initiating 150 mg 3TC had higher HIV RNA, lower eGFR, and more comorbidities than those initiating 300 mg 3TC. The prevalence of relevant diagnoses and laboratory abnormalities was similar in both groups. The most common lab abnormality was low hemoglobin. There was no statistically significant difference in incident adverse diagnoses/severe lab abnormalities with 300 mg versus 150 mg (incidence rate ratio [IRR]: 1.51; 95% confidence interval [CI]: 0.59, 3.92). However, a statistically significant association was observed when gastrointestinal symptoms/moderate lab abnormalities were included in the outcome (IRR: 3.07, 95% CI: 1.12, 8.40). CONCLUSIONS Because 3TC is a well-tolerated drug with a wide therapeutic window, dose adjustment may be unnecessary among PLWH with eGFR between ≥30 and ≤49 ml/min/1.73m2. Clinical judgement is key when weighing the risks and benefits of 3TC dose adjustment for PLWH experiencing gastrointestinal symptoms or moderate lab abnormalities.