Laboratory testing in rheumatoid arthritis patients taking disease-modifying antirheumatic drugs: Clinical evaluation and cost analysis

Objective. To develop and validate evidence-based recommendations for routine laboratory tests in patients with rheumatoid arthritis (RA) receiving traditional disease-modifying antirheumatic drugs (DMARDs), and to calculate the monitoring costs. Methods. Outpatient charts of 362 RA patients taking DMARDs were reviewed, and all laboratory abnormalities recorded. Recommendations on monitoring DMARD therapy were derived and then tested in an independent validation cohort of 231 patients. Cost analysis was performed using a cost catalog. Results. Laboratory abnormalities were seen in 10% of treatment courses; relevant abnormalities were seen only during the first 4 months of therapy. Laboratory tests should be performed in week 2 and 4, then monthly for the first 4 months of therapy, then 2 to 4 times per year. These were capable of detecting 98.3% of laboratory abnormalities in a timely manner in another RA cohort. Up to 78% of costs can be saved when the presented recommendations are compared with those of international rheumatology societies. Conclusion. Laboratory tests can be reduced substantially in patients receiving DMARD therapy. In consequence, costs can decrease significantly without oversight of adverse events.