Background: The onset of disease in ankylosing spondylitis (AS) is generally earlier than in other joint diseases, exposing patients to a prolonged burden of disease. Whether this is associated with excess mortality is still uncertain. Radiation therapy for AS has previously been shown to increase mortality. The present study investigated standardised mortality ratios, causes of death and survival predictors in a large regional cohort of patients with AS.
Method: A total of 677 patients with AS followed at our hospital since 1977 were matched by gender, age and postal area to three controls from the general population and standardised mortality rates (SMRs) were calculated. Cause of death was established using patients' hospital records. In a subset of 360 patients, clinical and demographic data collected during an earlier research visit (1998-2000) were used in a prospective multivariate analysis of predictors for mortality in AS.
Results: The crude mortality among patients with AS in this study was 14.5% (98 patients); SMR was only significantly increased among male patients compared with female patients (1.63 vs 1.38, p<0.001). Circulatory disease was the most frequent cause of death (40.0%), followed by malignant (26.8%) and infectious (23.2%) diseases. Factors independently associated with reduced survival were diagnostic delay (OR 1.05), increasing levels of C-reactive protein (OR 2.68), work disability (OR 3.65) and not using any non-steroidal anti-inflammatory drugs (OR 4.35).
Conclusions: Mortality is increased in patients with AS and circulatory disease is the most frequent cause of death. Parameters reflecting the duration and intensity of inflammation are associated with reduced survival. These results indicate that, to improve long-term survival in AS, there is a need for early detection and anti-inflammatory treatment as well as a vigilant approach for cardiovascular risk factors.