Life expectancy, standardized mortality ratios, and causes of death in six rheumatic diseases in Hong Kong, China

Abstract

Objective: To examine the life expectancy, standardized mortality ratios (SMRs), and causes of death in 6 groups of patients from Hong Kong with different rheumatic diseases.

Methods: Patients with a diagnosis of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), ankylosing spondylitis (AS), psoriatic arthritis (PsA), systemic vasculitis (SV), or systemic sclerosis (SSc) registered in 37 public hospitals between 1999 and 2008 were identified in the hospital registry. SMRs were calculated by comparing the mortality rate in patients with each disease with that in the general population. Life expectancy was calculated by abridged life-table analysis, and the causes of death were compared.

Results: In 2008, data on 8,367 RA, 5,243 SLE, 2,154 AS, 1,636 SV, 778 PsA, and 449 SSc patients were available in our registry. The age- and sex-adjusted SMRs were highest for SLE (5.25 [95% confidence interval 4.79-5.70]), SSc (3.94 [95% confidence interval 3.20-4.68]), and SV (2.64 [95% confidence interval 2.36-2.93]). In female patients, the loss in life expectancy was greatest for SSc (34.1 years), SV (19.3 years), and SLE (19.7 years). In male patients, the loss in life expectancy was highest for SV (28.3 years), SLE (27 years), and SSc (16 years). There were 2,486 deaths during the study period (1999-2008), and the principal causes were infections (28%), cardiovascular complications (18%), cancer (16%), and disease activity (7%). Infection was the leading cause of death in SLE, RA, AS, and PsA, whereas deaths from disease-related activity and cardiovascular complications were most frequent in SSc. Cancer was the most common cause of death in SV.

Conclusion: Our findings indicate that patients with SLE, RA, AS, PsA, SV, and SSc have increased mortality rates and reduced life expectancy. SLE has the highest adjusted SMR, and female SSc patients have the greatest loss in life expectancy. Infection is the leading cause of death, followed by cardiovascular complications and malignancies.