Risk and timing of isotretinoin-related laboratory disturbances: a population-based study.

INTRODUCTION:Uncertainty surrounds the optimal routine laboratory monitoring in acne patients treated with isotretinoin. OBJECTIVE:Our aim was to evaluate the risk of mild and severe laboratory abnormalities in patients with acne starting isotretinoin versus oral antibiotic treatment. METHODS:A global population-based retrospective cohort study assigned two groups of patients with acne-prescribed isotretinoin (n = 79,012) and oral antibiotics (n = 79,012). Comprehensive propensity-score matching was conducted. RESULTS:Compared to acne patients treated with oral antibiotics, those under isotretinoin demonstrated an increased risk of grade ≥3 hypertriglyceridemia (hazard ratio [HR], 7.85; 95% confidence interval [CI], 5.58-11.05; P < 0.001) and grade ≥3 elevated aspartate transaminase (AST) levels (HR, 1.45; 95% CI, 1.13-1.85; P = 0.003) within the initial 3 months of treatment. The absolute risk of these abnormalities among isotretinoin initiators was 0.4% and 0.2%, respectively. The risk difference of these findings was clinically marginal: 3 and 1 additional cases per 1,000 patients starting isotretinoin, respectively. There was no significant risk of grade ≥3 impairment in cholesterol, alanine transaminase, gamma-glutamyl transferase, or creatinine levels under isotretinoin. Most laboratory abnormalities were documented 1-3 months after drug initiation in time-stratified analysis. CONCLUSION:Isotretinoin is associated with a clinically marginal increased risk of severe hypertriglyceridemia and hypertransaminasemia. Routine blood testing should be performed 1-3 months after commencing therapy.