Background: Red flags and atypical symptoms have been described as being useful in suggesting alternative diagnoses to multiple sclerosis (MS) and clinically isolated syndrome (CIS); however, their diagnostic utility has not been assessed. The aim of this study was to establish the predictive value of red flags and the typicality/atypicality of symptoms at presentation in relation to the final diagnosis of patients referred with suspected MS.
Methods: All patients referred with suspected MS over a 3-year period were assessed by the typicality of the clinical presentation and the occurrence of red flags in relation to the eventual diagnosis. The extent of agreement of trainee and consultant neurologists as to typicality of clinical presentations was determined.
Results: Of 244 patients referred, 119 (49%) had MS/CIS and 125 (51%) did not. 41 patients were referred because of an abnormal MRI. Of 203 with clinical symptoms, 96 patients had atypical symptoms of whom, 81 (84%) did not have MS and 15 (16%) had MS/CIS. Typical symptoms occurred in 107 patients; 10% did not have MS/CIS. Atypical symptoms had a sensitivity of 84%, specificity of 90% and positive likelihood ratio (PLR) of 8.4, whereas red flags had a sensitivity of 47%, specificity of 88% and PLR of 3.9 for the exclusion of MS/CIS. Mean percentage agreement between consultants and trainees was 73% with a range of 32-96%.
Conclusions: Atypical features at presentation are more sensitive, specific and have a higher PLR than red flags to refute a diagnosis of MS/CIS.