To study the annual incidence and standardized mortality ratio (SMR) of a longitudinal cohort of Chinese patients with systemic lupus erythematosus (SLE).
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.
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.
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.