Sex differences in disease severity among patients with systemic lupus erythematosus.

Background: Systemic lupus erythematosus (SLE), a prototypical autoimmune disease, often results in comorbidities from exposure to medications as well as from chronic inflammation. Identification of gender-based differences in comorbidities and disease severity may assist health practitioners in providing optimum care for those living with SLE.

Objective: The purpose of this study, which utilized hospital discharge data collected during a 7-year period to garner a large SLE patient sample, was to determine the effect of gender on SLE comorbidities and disease severity.

Methods: Patients were hospitalized in the Dallas-Fort Worth metropolitan statistical area between 1999 and 2005 and had a diagnosis of SLE. The sample consisted of 14,829 patients with SLE, 10% of which were male. ANOVAs were conducted to test for differences between males and females for disease severity, age, length of stay in the hospital, total hospital charges, and number of autoimmune diseases. Disease severity was measured with the SLE comorbidity index, which weights 14 conditions in SLE. We identified the top 30 comorbidities as well as the odds of experiencing the secondary illnesses by gender.

Results: Male patients had significantly greater disease severity compared with female patients. Additionally, female patients had more autoimmune diagnoses compared with male patients. Male patients were more likely to have cardiovascular and renal comorbidities compared with female patients. Female patients had significantly greater odds of diagnoses of urinary tract infection, hypothyroidism, depression, esophageal reflux, asthma, and fibromyalgia.

Conclusions: Although the prevalence of SLE among males is rare, male patients have the potential for greater disease severity and are more likely to suffer from cardiovascular and renal disease. Gender differences in disease severity should be further evaluated, but with the added recommendation to develop an index with conditions more indicative of active SLE.