Characteristics of the studies examined in the meta-analysis.

AD: autoimmune disease, qBHs: Quantitative score of the Bradford Hills Criteria for causation. AS: ankylosing spondylitis. RA: rheumatoid arthritis. SSc: systemic sclerosis. SLE: systemic lupus erythematous, OS: Organic solvent. GN: glomerulonephritis,NPR: National population Register; N: number of subjects in each group. OR 95% CI: Odds ratio with 95% confident interval. MS: multiple sclerosis. NA: not available data. PBC: primary biliary cirrhosis. AOR: Adjusted odds ratio. PSV: primary systemic vasculitis, WG: Wegener's granoulomatosis. RD: Raynaud's disease. TCE: trichloroethylene.