Objective: Oligoclonal band (OCB) negative multiple sclerosis (MS) is well recognised but uncommon, studied in only a few usually small case series. These reached differing conclusions on whether its clinical features or course differ from OCB positive disease. The study hypothesis was that a definitive study would not only be of clinical and prognostic value but also potentially offer information about the possible role of CSF oligoclonal immunoglobulins in MS disease processes.
Methods: A collaborative cohort of well documented patients in southwest England and south Wales was used to identify and analyse a large group of patients with OCB negative MS and make comparisons with age and sex matched OCB positive controls.
Results: An approximate minimum 3% of patients with MS were OCB negative. They were significantly more likely to exhibit neurological or systemic clinical features atypical of MS (headaches, neuropsychiatric features and skin changes). Non-specific MRI, blood and (other) CSF abnormalities were also more common, emphasising the need for continued diagnostic vigilance, although the incautious application of McDonald diagnostic criteria in OCB negative cases renders categorisation as "definite" MS more likely. Studying the uniformly assessed Cardiff group (69 patients), we found the prognosis for neurological disability was significantly better for OCB negative cases. The age adjusted hazard ratio for OCB negative and OCB positive subjects to reach Disability Scale Status (DSS) 4 and DSS 6 was, respectively, 0.60 (95% CI 0.39 to 0.93; p = 0.02) and 0.51 (95% CI 0.27 to 0.94; p = 0.03).
Conclusion: There are clear clinical differences between OCB negative and OCB positive MS, in particular a better prognosis for disability. This is consistent with a secondary but nonetheless contributory role in disease process for intrathecally synthesised immunoglobulins.