To Dose-Adjust Or Not To Dose-Adjust: Lamivudine Dose In Kidney Impairment

Objectives: To assess the risk of adverse diagnoses and laboratory abnormalities associated with a 300 or 150 mg daily dose of lamivudine (3TC) initiated by people with HIV (PWH) with an estimated glomerular filtration rate (eGFR) between at least 30 and 49 ml/min per 1.73 m(2) or less. Design: Longitudinal study based on electronic health records of 539 PWH with eGFR between at least 30 and 49 ml/min per 1.73 m(2) or less 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 PWH without the relevant diagnoses or laboratory abnormalities at 3TC initiation. Results: PWH 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). Conclusion: As 3TC is a well tolerated drug with a wide therapeutic window, dose adjustment may be unnecessary among PWH with eGFR between at least 30 and 49 ml/min per 1.73 m(2) or less. Clinical judgement is key when weighing the risks and benefits of 3TC dose adjustment for PWH experiencing gastrointestinal symptoms or moderate lab abnormalities.