Methotrexate Monitoring in Dermatology— A Retrospective Cohort Study

March 2021 | Volume 20 | Issue 3 | Original Article | 320 | Copyright © March 2021


Published online February 18, 2021

Alina Gertrud Zufall BA, Bharath Rama BS, Emily Katherine Ninmer BA, Stephany Lynn Vittitow BA, Miyabi Saito BS, Mary Margaret Noland MD, R Hal Flowers MD

Department of Dermatology, University of Virginia School of Medicine, Charlottesville, VA

Abstract
Background and Objectives: There are currently no evidence-based recommendations to guide lab monitoring in the first 90 days of methotrexate treatment. The purpose of this study was to determine whether certain monitoring practices or baseline patient characteristics were associated with increased risk of developing clinically meaningful lab abnormalities during the course of methotrexate treatment.
Patients and Methods: This retrospective cohort study analyzed 243 dermatologically managed patients taking methotrexate at the University of Virginia Health System. Odds ratios were used to analyze the risk of these patients developing lab abnormalities that result in a change in clinical management, referred to as clinically relevant events. Chi-square analysis was used to determine the optimal timing of methotrexate lab monitoring.
Results: A diagnosis of congestive heart failure (P=0.03), chronic kidney disease (P=0.03), and an initial low platelet count (P=0.008) increased the odds of developing a clinically relevant event at some point during methotrexate therapy. In the first 15 days following methotrexate initiation, only 1/114 (0.9%) lab draws resulted in discontinuation of the medicine, 1/114 (0.9%) resulted in maintenance of a stable dose, and 2/114 (1.8%) resulted in repeat laboratory testing.
Conclusion: In the absence of concerning baseline patient characteristics, dermatologists may consider postponing initial lab monitoring until 15 days post methotrexate initiation.

J Drugs Dermatol. 2021;20(3):320-325. doi:10.36849/JDD.2021.5790

INTRODUCTION

Methotrexate (MTX) is an immunosuppressive medication used to treat a wide range of dermatological conditions, most commonly psoriasis.1 MTX was first approved by the Food and Drug Administration (FDA) in 1972 for the treatment of severe, recalcitrant psoriasis.2 This was before the acceptance of randomized control trials as the standard to judge drug efficacy. Therefore, there have been no large-scale, high quality studies looking at the efficacy and safety of MTX to date.2 For this reason, dermatology guidelines regarding MTX treatment were written, and continue to be revised, based solely on expert opinion.

MTX use requires intermittent monitoring of blood counts, renal function, and liver function. However, current laboratory monitoring guidelines for dermatological patients on MTX are variable, particularly within the first 90 days of therapy, and practices are highly provider and institution dependent.3 For example, the most recent edition of Comprehensive Dermatologic Drug Therapy, which is often referenced by dermatology residents and attending physicians, cites guidelines written in 1988 by Roenigk et al, who recommend obtaining a complete blood count (CBC), platelet count, and liver function tests (LFTs) every 1–2 weeks for the first 2–4 weeks, 1–2 weeks after dose escalations, and a gradual decrease to every 3–4 months long term.4 The British Association of Dermatologists, similarly, recommends obtaining a CBC, LFTs, urea and electrolytes every 7–14 days for the first month, decreasing to every 2–3 months once therapy has stablized.5 Guidelines from the 2009 National Psoriasis Foundation Conference, on the other hand, endorse obtaining a CBC with platelet count every 2–4 weeks for the first several months, then every 1–3 months depending on the stability of the patient.6

Rheumatology guidelines governing MTX blood monitoring are generally less stringent.7 A study performed by Busger op Vollenbroek et al in 2018 determined that strict monitoring by dermatologists led to more abnormal findings and reduced drug survival, with no difference in the number of serious adverse events when compared to rheumatology patients.1

The purpose of this study was to gain a clearer understanding of methotrexate monitoring practices currently being utilized by dermatologists at one institution. Specifically, we sought