Objective: To study the annual incidence and standardized mortality ratio (SMR) of a longitudinal cohort of Chinese patients with systemic lupus erythematosus (SLE).
Methods: Annual numbers of new cases and deaths in a longitudinal cohort of patients with SLE between 2000 and 2006 retrieved from a database were compared with regional population and death rates expected from the annual death statistics maintained by our hospital and population census data.
Results: Our cohort of SLE had grown from 272 to 442 patients from 2000 to 2006. The annual incidence of SLE showed mild fluctuation (mean incidence 3.1/100,000 population; 5.4/100,000 in women). The annual death rate and SMR in year 2000 were 25.7/1000 and 7.88 (range 3.7-16.7; p<0.001), respectively, compared to the general population. A trend of reduction in annual death rates and SMR was observed, the annual death rate and SMR in year 2006 being 6.8/1000 and 2.17 (range 0.7-6.7; p=0.34). The SMR was higher in men than women and had a less obvious trend of improvement. A negative correlation of SMR with age was observed. The SMR of SLE patients aged above 60 years was not significantly higher than expected from population statistics. There was also a trend of fewer deaths due to infection over time.
Conclusion: In this single-center study, the incidence of SLE remained static. The SMR of SLE was significantly increased in younger patients, indicating a greater effect of the disease on younger individuals. There was a trend of improvement in SMR for SLE in recent years, probably as a result of fewer infectious complications.