Routine blood monitoring in acne vulgaris patients on isotretinoin: Is reassessment warranted? A retrospective cohort study from Tygerberg Hospital

Background. Oral isotretinoin is an indispensable treatment for patients with resistant and severe acne vulgaris, both in South Africa (SA) and globally. While routine laboratory monitoring is often deemed unnecessary for young, healthy patients, it remains unclear whether this applies in the SA context. Objectives. To assess the need for routine blood monitoring for acne vulgaris patients on isotretinoin treatment at Tygerberg Hospital, SA. Specifically, we wanted primarily to determine the prevalence of patients with acne vulgaris whose oral isotretinoin treatment was altered owing to blood result abnormalities, and secondarily, to determine the prevalence of adverse events and liver function and lipid profile abnormalities associated with isotretinoin. Methods. This was a retrospective cohort study of hospital records from patients with acne vulgaris treated with oral isotretinoin at the dermatology clinic at Tygerberg Hospital between 1 January 2020 and 31 December 2023. There were 89 eligible records extracted from the Tygerberg Hospital Enterprise Content Management system. Baseline and 6-week follow-up laboratory data, including liver function tests and lipid profile, were extracted retrospectively from the National Health Laboratory Service. Results. The sample comprised 89 patient hospital records, 62% male and 38% female. Of the total, 53% were aged between 12 and 20 years. Blood result abnormalities led to alterations in treatment regimens for 2/89 (2.2%) patients: one patient required treatment termination, while another continued on low-dose isotretinoin instead of the planned dose increase. Two patients (2.2%) developed increased aspartate aminotransferase levels and five (5.6%) developed new alanine aminotransferase increases above the upper limit of the normal range. Elevated triglyceride levels occurred in two patients (2.2%), and elevated cholesterol levels in nine (10.1%). Adverse events resulting in the premature termination of treatment with isotretinoin included one case of severe chest pain, one patient with pseudotumour cerebri and one patient who developed exuberant granulation tissue. Conclusion. This single-centre retrospective review highlights the scarcity of blood result abnormalities due to isotretinoin in patients with acne vulgaris. There were only two patients (2.2%) who had their management altered owing to blood result abnormalities, and both had chronic conditions. This may suggest that routine monitoring is indicated in patients with comorbidities, but not in otherwise healthy young patients with acne. However, larger prospective studies are needed in SA before such conclusions can be drawn.