Mortality Rates in Patients With Ankylosing Spondylitis With and Without Extraarticular Manifestations and Comorbidities: A Retrospective Cohort Study

Abstract

Objective. To examine mortality rates in hospitalized patients with ankylosing spondylitis (AS) and the association of extraarticular manifestations (EAMs) and comorbidities with mortality rates. Methods. This study was a retrospective, population-based cohort study using linked administrative data from patients with AS who were hospitalized (n = 1791) and patients in a matched comparison group (n = 8955). Mortality data for patients were obtained from the Western Australia Death Register. The presence of EAMs and comorbidities was identified from hospital records. Mortality rates were compared between the 2 groups using Cox proportional hazard models overall and stratified by a history of EAMs, comorbidities, and smoking status. Results. Crude mortality rates were significantly higher among patients with AS than among patients in the comparison group (hazard ratio [HR] 1.85, 95% CI 1.62–2.12), with excess mortality in the AS group associated with cardiovascular disease (CVD; HR 5.32, 95% CI 3.84–7.35), cancer (HR 1.68, 95% CI 1.27–2.23), external causes (HR 3.92, 95% CI 2.28–6.77), and infectious diseases (HR 25.92, 95% CI 7.50–89.56). When patients were stratified by history of EAMs, CVD, and smoking, the risk of mortality was elevated in patients both with and without each risk factor. Among patients with AS, histories of CVD (HR 6.33, 95% CI 4.79–8.38), diabetes (HR 2.81, 95% CI 1.99–3.95), smoking (HR 1.49, 95% CI 1.18–1.89), and EAMs (HR 1.62, 95% CI 1.24–2.11) were associated with an increased risk of mortality. Conclusion. The presence of comorbidities, EAMs, and smoking contributes to an increased risk of all-cause mortality among patients with AS who are hospitalized compared to patients in the comparison group. These results support the need to prevent or reduce the occurrence of comorbidities and smoking in patients with AS.