Assessing the relative impact of lupus nephritis on mortality in a population-based systemic lupus erythematosus cohort.

OBJECTIVE: There is limited knowledge on the relative impact of lupus nephritis (LN) on morbidity and mortality in population-based systemic lupus erythematous (SLE) cohorts. Here, the primary aim was to compare mortality rates between patients with and without LN in a population-based SLE cohort. METHODS: The study cohort included all SLE patients resident in the city of Oslo during 1999-2008. Follow-up time was median 14 (0-15) years. Presence of LN was defined according to the 1987 American College of Rheumatology classification criteria for SLE. LN class was determined by renal biopsy. Data on kidney function, including presence of end-stage renal disease (ESRD), were obtained from patient charts. Standardized mortality ratios (SMRs) were estimated by comparing deaths in the SLE cohort with age- and gender-matched population controls. RESULTS: We found that 98/325 SLE patients (30%) developed LN, 92% of whom had occurrence within the first five years from disease onset. Incidence rate of ESRD was 2.3 per 1000 patient-years. A total of 56 deaths occurred during the study period, corresponding to an overall SMR in the SLE cohort of 2.1 (95% confidence interval (CI) 1.2-3.4). Estimated SMR for LN patients was 3.8 (95% CI 2.1-6.2), and for SLE patients without LN it was 1.7 (95% CI 0.9-2.7). CONCLUSION: In this population-based SLE cohort, we found that LN was associated with increased morbidity and mortality, whereas SLE patients who did not develop LN had good overall prognoses regarding survival.

Mortality and years of potential life loss in systemic lupus erythematosus: a population-based cohort study.

Multiple sources were used to identify 325 systemic lupus erythematosus (SLE) patients within the city of Oslo during 1999-2009 who met ≥ 4 of the American College of Rheumatology (ACR) criteria. The survival, standard mortality rate (SMR), years of potential life loss before 60 years of age (YPLL60) and causes of death of these patients were examined and compared to a matched control population. Only inception cases (127) were studied in the calculation of survival. The analysis includes underlying, immediate and contributing causes of death. The five- and 10-year survival was 95% and 90%, respectively, which was significantly reduced when compared to the general population. A total of 50 SLE patients died during the study period. Overall SMR was 3.0 (95% confidence interval (CI) 2.2-3.8) with the highest SMR found for female patients aged 16-39 years old. SLE patients had a 10 times higher rate of YPLL60 compared to the control group. YPLL emphasizes active disease and reduces the importance of cancer as a cause of death in SLE. This study demonstrates that YPLL gives additional and useful information for the prognosis of SLE, supplementing traditional methods of measuring mortality.

High incidence and prevalence of systemic lupus erythematosus in Norway.

Our aim was to identify all patients with systemic lupus erythematosus (SLE) within the city of Oslo from 1999-2008 and to estimate the incidence and prevalence of SLE according to age, sex and ethnicity. Adults (16 years and over) with SLE were identified from five different sources. Only patients fulfilling four or more of the updated 1997 American College of Rheumatology (ACR) criteria were included. The incidence was stable during the nine year study period, with a mean annual incidence rate of 3.0 per 100,000 at risk (95% confidence interval (CI) 2.4-3.5). Females exhibited a bimodal pattern in age specific incidence with the first peak at 16-29 years of age and the second at 50-59 years of age. The overall prevalence was 51.8 per 100,000 population (95% CI 45.2-58.4), with 91.0 (95% CI 78.8-103.1) for females and 10.7 (95% CI 6.4-15.0) for males. The prevalence proportions for European descendants were similar to those for Asians but statistically significant lower than those for individuals adopted from non-European countries. The findings indicate a higher prevalence in Norwegians compared to Caucasians in Denmark and England. The higher prevalence of SLE in foreign adopted individuals warrants further examination.