Variability and predictors of isotretinoin dosing in patients with acne: a retrospective cohort study.

BACKGROUND

Isotretinoin prescription for acne varies widely, partially due to inconsistent guidelines. This leaves physicians to rely on clinical judgement, experience and institutional practices.

OBJECTIVES

We examined real-world isotretinoin prescribing patterns among dermatologists in a large healthcare system, focusing on dosing variability and predictors of total cumulative dosage.

METHODS

This retrospective cohort study at Kaiser Permanente Northern California (KPNC) included 9551 KPNC members aged 13-40 years who received at least 1 isotretinoin prescription for acne between 1 January 2016 and 31 December 2022. The primary outcome was cumulative isotretinoin dose (mg kg-1). Secondary outcomes included starting and maximum daily doses, time to maximum dose, and total treatment duration.

RESULTS

Among 9551 participants, most were < 18 years old (5609, 59%), with an equal split between male and female patients (female: 4911, 51%). Common starting doses were 0.5-0.75 mg kg-1 per day (4809 of 9326, 52%), with 35% reaching a maximum of 1-1.25 mg kg-1 per day. The mean cumulative dose was 137 mg kg-1 (SD 62.5), with 25% of patients receiving 120-150 mg kg-1. This is consistent with the 2016 American Academy of Dermatology guidelines. Doses > 175 mg kg-1 were used in 25%. Significant predictors of higher cumulative dosing included female sex, younger age, prior antibiotic use and more acne-related visits. Additionally, Asian and White patients received significantly higher cumulative doses than Black patients.

CONCLUSIONS

This study highlights substantial variability in isotretinoin prescribing practices. Although medium-range cumulative doses aligned with previous guidelines, there was substantial variability in cumulative dosing. These findings highlight the need for comparative studies of alternative dosing strategies. More comprehensive guidelines incorporating alternative dosing models could optimize acne treatment and ensure equitable care.