Brief Report: Hospitalizations in a Clinical Systemic Lupus Erythematosus Cohort, 1999-2011
DOI:
https://doi.org/10.12970/2310-9874.2014.02.02.3Keywords:
Systemic lupus erythematosus, hospitalization, admission.Abstract
Introduction: Health resource use is believed to be significant in systemic lupus erythematosus (SLE). Yet to our knowledge there are no comparisons of hospitalization rates in SLE patients vs. the general population. Our objective was to provide recent estimates for hospitalization rates in a large clinical SLE cohort, stratifying by age and sex, and to compare this to the general population.
Methods: We evaluated data from SLE patients on self-reported hospitalizations (in the past year) collected through annual research visits from 1999-2011. We compared hospitalization rates of the SLE patients to the Canadian general population by calculating the standardized incidence ratio (SIR). This represents the ratio of the number of events observed in the SLE cohort to the number of events that would be expected based on Canadian general population hospitalization rates (accounting for age and sex).
Results: Over the interval studied, 433 SLE patients (401 female) provided 2,535 person-years of follow-up. There were 350 reported admissions with an incidence of 13.8 hospitalizations per 100 person-years (13.7 in females, 15.6 in males).
The overall SIR was 1.52; 95% confidence interval (CI) 1.37, 1.69. Stratified by sex, the SIR was 2.18 (95% CI 1.47, 3.11) for males and 1.48 (95% CI 1.32, 1.65) for females. However, stratifying further by age, female SLE patients aged 65 and older tended to have fewer hospitalizations than expected, based on age/sex-specific general population rates.
Conclusions: We documented high rates of hospitalization in SLE, particularly for males. The evidence suggests at least a 50% increase in hospitalization rates in the SLE cohort compared to the general population. The low number of hospitalizations in female SLE patients >65y may be due to chance (since patients aged >65y are a relatively small group), or may be biased by poor self-report or survivorship issues. This demographic thus warrants particular attention in future studies of hospitalization in SLE.
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