COMMENTARY

Do Acne Patients on Isotretinoin Need Monthly Blood Tests?

Graeme M. Lipper, MD

Disclosures

March 14, 2016

Laboratory Monitoring During Isotretinoin Therapy for Acne: A Systematic Review and Meta-analysis

Lee YH, Scharnitz TP, Muscat J, Chen A, Gupta-Elera G, Kirby JS
JAMA Dermatol. 2016;152:35-44.

Oral isotretinoin is a highly effective treatment for nodulocystic acne; it has been prescribed for over four decades. The synthetic retinoid activates retinoic acid receptors on keratinocytes and sebocytes, yielding potent comedolysis while reducing sebum production. Unfortunately, the high efficacy of isotretinoin comes with the price of potentially severe side effects. These include potent teratogenicity, hepatotoxicity, hyperlipidemia, and pancytopenia.

Routine laboratory monitoring during therapy helps to detect these abnormalities before they become clinically significant, but the frequency of testing varies in clinical practice owing to a lack of consensus.[1] The isotretinoin package insert recommends baseline fasting lipid and hepatic panels, with repeated testing "at weekly or biweekly intervals until the response has been established." In contrast, multiple prior studies have concluded that only baseline fasting lipid and hepatic panels with one follow-up test are necessary,[2,3] and one of these studies found that most blood abnormalities occur within the first 2 months of therapy.[3]

Study Summary

Excessive laboratory monitoring poses a nuisance to patients and an added financial burden to a healthcare system that is already taxed with high diagnostic and pharmaceutical costs. Lee and colleagues used data from 26 studies of isotretinoin for acne (1574 patients, aged 9-35 years) to estimate the prevalence of laboratory abnormalities during isotretinoin therapy, and determine when most of these changes occurred and whether these abnormalities constituted "severe or high-risk events."

All clinical trials used isotretinoin for acne vulgaris at dosages at least 40 mg/day, administered for at least 4 weeks. The main outcome measures were laboratory values for lipid levels, complete blood cell count (CBC), and liver function tests.

Key findings were as follows:

  • Although mean values for all of these variables changed during isotretinoin therapy (elevations in triglyceride/cholesterol levels and liver function values; drop in CBC), few of these abnormalities met "high-risk" criteria;

  • Laboratory abnormalities occurred only in a low proportion of patients taking isotretinoin—the mean from all studies was 4.4%; and

  • Changes in total cholesterol and triglyceride levels from baseline to 8 weeks vs 20 weeks of isotretinoin therapy were similar.

Viewpoint

This large meta-analysis supports a growing consensus that patients with acne who are taking isotretinoin do not need monthly laboratory monitoring,[4] unless they have independent risk factors for liver, hematopoetic, or lipid dysfunction. Lee and colleagues also found that most laboratory abnormalities are detected during the first 8 weeks of isotretinoin therapy, in agreement with prior studies.[2,3]

One limitation of Lee and colleagues' study is the lack of any direct correlation between laboratory abnormalities and discontinuation (mean rate, 5%) or disruption of isotretinoin therapy. For example, we do not know how many patients stopped taking isotretinoin owing to laboratory abnormalities vs noncompliance or clinically significant side effects (eg, joint pain, headaches, ocular side effects, adverse cutaneous effects).

Taken in sum, Lee and colleagues' findings justify limiting laboratory monitoring for healthy patients with acne who are taking oral isotretinoin. Their data support checking isotretinoin lab values at baseline, then once or twice during the first 8 weeks of therapy. More frequent laboratory monitoring should be done to follow any abnormalities detected during early therapy, or in patients with a medical history of liver disease, hyperlipidemia, hypercholesterolemia, or abnormal CBCs. Closer laboratory monitoring may also be needed for patients taking other medications associated with hepatotoxicity, bone marrow suppression, or dyslipidemia.

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