Genetic testing utilization for patients with neurologic disease and the limitations of claims data

To determine the utilization of genetic testing in patients seen by a neurologist within a large private insurance population.

Using the Optum health care claims database, we identified a cross-sectional cohort of patients who had been evaluated by a neurologist no more than 30 days before initial genetic testing. Within this group, we then categorized genetic testing between 2014 and 2016 on the basis of the Current Procedural Terminology (CPT) codes related to molecular and genetic testing. We also evaluated the International Classification of Disease Version 9 Clinical Code Classifications (ICD-9 CCS) associated with testing.

From 2014 to 2016, a total of 45,014 claims were placed for 29,951 patients who had been evaluated by a neurologist within the preceding 30 days. Of these, 29,926 (66.5%) were associated with codes that were too nonspecific to infer what test was actually performed. Among those claims where the test was clearly identifiable, 7,307 (16.2%) were likely obtained for purposes of neurologic diagnosis, whereas the remainder (17.2%) was obtained for non-neurological purposes. An additional 3,793 claims (8.4%) wherein the test ordered could not be clearly identified were associated with a neurology-related ICD-9 CCS.

Accurate assessment of genetic testing utilization using claims data is not possible given the high prevalence of nonspecific codes. Reducing the ambiguity surrounding the CPT codes and the actual testing performed will become even more important as more genetic tests become available.