The mortality and causes of death of patients with "hypergamma type" of ankylosing spondylitis.

The mortality and causes of death of 64 patients with ankylosing spondylitis (AS) were investigated. The mean follow-up time was 30 years. Eighteen patients had hypergammaglobulinaemia (serum gammaglobulin level less than 23.6 milligrams). A total of 36 deaths occurred during the follow-up time, 13 in the hypergammaglobulinaemia group and 23 in the control group. Six patients in the hypergammaglobulinaemia group and three in the control group died from uraemia caused by renal amyloidosis. The difference was statistically significant (p less than 0.01). It seems that hypergammaglobulinaemia may be a bad prognostic sign, at least when possible renal amyloidosis and uraemia are concerned.