Background Despite improved management of Systemic Lupus Erythematosus (SLE) an increased mortality compared to the population is recognized. Analyzing the cause of death pattern over en extended time period could be important in preventing premature mortality in SLE.
Objectives 1. Is the mortality rate in SLE increased and has the mortality rate changed over time? 2. Has the cause of death pattern changed in SLE over time?
Methods In 1981, a long term follow-up study of SLE was initiated in southern Sweden. The study comprises recurrent reviews of diagnosis registers and immunologic data with an analysis of medical records in a large number of possible SLE-cases in order to identify all patients diagnosed with SLE in 8 counties with a population of ∼200.000 adult individuals. Subsequently, the identified SLE cases are followed prospectively at the Department of Rheumatology in Lund. In the current study on mortality, patients receiving their diagnosis between 1981 and 2006 were included. Clinical data were recorded through 2013 ensuring at least 7 years of possible follow-up in all patients. Causes of death were collected from medical records and from the cause of death registry at The National Board of Health and Welfare in Sweden. Population data including number of deaths in the 8 counties during the time period were collected from the population register at the National Board of Health and Welfare. From these data, standardized mortality rate (SMR) for the SLE-cohort was calculated. Furthermore, the mortality rates between the SLE-patients receiving their diagnosis 1981-1993 and 1994-2006 was compared (mortality rate ratio, MRR). Finally, the cause of death pattern was analyzed over time.
Results In all, there were 60 deaths in the 175 patients included. The total follow-up time was 2917 patient-years. Mean disease duration at time of death was 9.9 years and 27 percent of deaths occurred within 5 years of diagnosis. We found an increased mortality rate for the SLE patients compared to the population (SMR 1.7 (95% CI: 1.3-2.2). SMR for the patient group diagnosed 1981-1993 was 1.5 (95%CI 1.1-2.1), compared to a SMR of 2.8 (95% CI 1.6-4.6) for the group diagnosed 1994-2006. The MRR comparing the early and late time period was 0.6 (95%CI 0.3-1.1). The most common cause of death was heart disease, including ischemic heart disease and congestive heart failure (45%). Deaths directly attributed to SLE were few (6.7%). Infection (13%), malignancy (13%) and stroke (6.7%) were also seen as primary causes of death, while rare causes recorded included chronic obstructive lung disease, ruptured abdominal aortic aneurysm, vascular dementia and pulmonary embolism. The cause of death pattern was similar depending on age at death, as well as depending on the age at SLE diagnosis. However, few deaths were seen in patients younger than 60 years of age (10%). Additionally, the time period during which the patients had received their SLE diagnosis did not have an impact on the cause of death pattern (1981-1993 vs 1994-2006).
Conclusions There is a substantially increased mortality in SLE-patients in Sweden. The mortality rate has not changed significantly over the last 30 years. The most common cause of death is cardiovascular disease and this pattern is consistent over time.
Disclosure of Interest None declared