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.
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.
In the absence of concerning baseline patient characteristics, dermatologists may consider postponing initial lab monitoring until 15 days post methotrexate initiation.