Diagnostic Accuracy of Oligoclonal Bands for CNS Autoimmune Disorders in Acutely Ill Adults

The presence of oligoclonal bands (OCBs) indicates an augmented immune response within the CNS and is integral to the diagnosis of multiple sclerosis (MS). Expert consensus panels recommend OCB testing for conditions other than MS, despite limited data to suggest diagnostic value. Our objectives were to evaluate the spectrum of disease etiologies associated with OCBs and determine the accuracy of OCBs in identifying autoimmune disorders affecting the CNS. This is a retrospective, observational, single health system study that captured all patients in acute care settings who underwent OCB testing from January 1, 2018, through December 31, 2020. Patient diagnoses and diagnostic categories were adjudicated by clinicians. Test accuracy characteristics to detect CNS autoimmune disorders were computed by comparing 2 or more OCBs as a positive index test against target disease etiologies as reference standards. OCB testing was performed across all etiologies in 926 patients; 78 patients had MS, and 148 had CNS autoimmune disorders not related to MS. Oligoclonal bands exhibited high sensitivity for MS but low sensitivity and low predictive power for other CNS autoimmune disorders. In contrast to their diagnostic accuracy in MS, OCBs exhibited limited discriminatory power in the detection of other autoimmune disorders affecting the CNS. Beyond suspected MS, OCBs should not be relied on as an accurate diagnostic tool because a positive result can manifest in an array of neurologic diseases and a negative result does not exclude an autoimmune etiology.