Autoimmune central nervous system testing at an academic medical center: the challenges of improving test utilization

We sought to improve test utilization for 8 autoimmune antibody panels.

Three interventions (test ordering guidance, clinical pathway guidance, and duplicate test blocking) were implemented at 6-month intervals. Over 3 years, we recorded trends in test volumes, duplicate tests, and positive results. We conducted chart reviews for two 3-month periods 1 year apart to assess the impact on patient Antibody Prevalence in Epilepsy and Encephalopathy (APE2) scores.

Comparing the first 6 months with the last 6 months of the 3-year study, we observed a 36.5% decrease in overall test volume and a 95.5% reduction in duplicate tests. The final true-positive rate based on clinical diagnosis was low, however, at only 1.6% (40/2550) of tests performed and 1.3% (24/1883) of patients tested. Performance did not improve over the study period. Chart reviews (n = 194) showed only 8 of 106 (7.5%) patients had an APE2 score of at least 4 in January through March 2023, and 12 of 88 (13.6%) met this threshold in January through March 2024. Two of 20 total patients with an APE2 score of at least 4 had a new diagnosis of autoimmune central nervous system disease compared with 0 of 174 patients with a score below 4 (P < .001), affirming the predictive value of the scorecard.

Although reductions in test volume and duplicate testing were observed, clinicians continued to order a substantial number of tests for patients whose clinical picture was not suggestive of autoimmune epilepsy or encephalopathy. Although there was some improvement in appropriate ordering when assessed by retrospective APE2 scores, this value did not reach statistical significance.