A systematic review 1 on the accuracy of magnetic resonance imaging criteria for the early diagnosis of multiple sclerosis included 29 studies (18 cohort studies, 11 other designs). Sample sizes were generally small (15 to 1500 patients, median 70). The longest average duration of follow-up was three years in studies that assessed the Barkhof, Fazekas, and McDonald 2001 criteria, and six years for studies that assessed the Paty criteria. Only two studies followed patients for more than 10 years. Studies with shorter follow-up tended to produce higher estimates of sensitivity and lower estimates of specificity compared with longer term studies. Even in the presence of many lesions (> 10 or > 8), magnetic resonance imaging could not accurately rule multiple sclerosis in (likelihood ratio of a positive test result 3.0 and 2.0, respectively). Similarly, the absence of lesions was of limited utility in ruling out a diagnosis of multiple sclerosis (likelihood ratio of a negative test result 0.1 and 0.5).
Comment: The quality of evidence is downgraded by imprecise results (limited study size for each comparison) and by limitations in study quality (e.g., inadequate follow up).
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