Disease associations may provide useful etiological leads in relation to diseases of unknown cause.
We conducted a hospital-based case-control study of 155 MS patients and 200 controls in Hordaland County, Norway to investigate the possible association between MS and autoimmune diseases.
The MS patients had a statistically significant more frequent coexistence of rheumatoid arthritis, psoriasis, and goitre when compared to the controls (OR = 2.96; 95% CI 1.23-7.66). This difference persisted when analysing the definite MS cases separately (OR = 2.90; 95% CI 1.10-7.96). The familial occurrence of chronic inflammatory diseases was not significantly different in cases and controls. A significant increased risk to develop MS occurred in first degree relatives of MS patients (OR = 12.58; 95% CI 1.73-552).
Acknowledging the low figures, the uncertain estimates with large confidence intervals, and thus the obvious role of chance in this study, the results might indicate that a generalized, genetically controlled problem of the immune system could result in aggregates of the reported diseases, all of which are partly characterized by aberrations of the immune system.