Immunonephelometric quantitation of central nervous system IgG synthesis in multiple sclerosis. Clinical evaluation using predictive value therapy

With a laser nephelometric immunoassay and an empirical formula for the quantitation of central nervous system (CNS) daily IgG synthesis, we studied prospectively a population of 101 individuals divided into four groups: 31 normals, 25 patients with definite multiple sclerosis (DMS), 18 patients with probable or possible multiple sclerosis (PMS), and 27 patients with neurologic disease other than multiple sclerosis (NMS). By the Kruskal-Wallis, test the results of the DMS and PMS patients were significantly different from the normals and NMS patients (P < 0.0003). Considering normals, DMDS, and NMS patients only, the sensitivity of the test was 96%, the specificity was 98%, the positive predictive value was 96%, the negative predictive value was 98%, and the efficiency was 98%. Based on our study data, we applied the predictive value theory to different hypothetical populations (our Neurology Ward, Northeastern U.S., and patients with optic neuritis and chronic progressive myelopathy). In all these situations, the test gave a diagnostic efficiency for multiple sclerosis greater then 95%.