Applying Choosing Wisely: Antinuclear Antibody (ANA) and Sub-Serology Testing in a Safety Net Hospital System

In 2013, the American College of Rheumatology (ACR) participated in the Choosing Wisely campaign and devised a recommendation to avoid testing antinuclear antibody (ANA) subserologies without a positive ANA and clinical suspicion of disease. The goals of our study were to describe ANA and subserology ordering practices and predictors of ordering concurrent ANA and subserologies in a safety-net hospital.

We identified ANA and subserologies (dsDNA, Sm, RNP, SSA, SSB, Scl-70 and centromere) completed at Denver Health between 1/1/2005 and 12/31/2011. Variables included demographics, primary insurance, service, and setting from which the test was ordered. We performed multivariable logistic regression to determine predictors of concurrent ordering of ANA and subserologies.

During seven years, 3221 ANA were performed in 2771 individuals and 211 (6.6%) were performed concurrently with at least one subserology. The most common concurrent subserologies were dsDNA (21.8%), SSA (20.8%), and SSB (19.7%). In the multivariable logistic analysis, significant predictors of concurrent ANA and subserologies were the labs being ordered from subspecialty care (OR 8.12, 95% CI 5.27-12.50, p-value <0.0001) or from urgent/inpatient care (OR 3.86, 95% CI 1.78-8.38, p-value 0.001). A significant predictor of decreased odds was male gender (OR 0.32, 95% CI 0.21-0.49, p-value <0.0001). Five individuals (2.2% of the negative ANA with subserologies ordered) had a negative ANA but positive subserologies.

Of 3221 ANA, 6.6% were performed concurrently with subserologies, and subspecialists were more likely to order concurrent tests. A negative ANA predicted negative subserologies with rare exceptions, which validates the ACR's recommendations.