Background/Purpose: Recent studies have suggested that body weight fluctuation in the general population is an independent risk factor for overall mortality. These findings are of particular concern for patients with systemic lupus erythematosus (SLE), who have a significantly elevated risk of mortality compared to the general population. However, little is known about the nature of body weight fluctuation and its association with mortality in SLE patients. We hypothesized that patients with SLE who had greater body weight fluctuation would have increased mortality risk compared to patients with SLE who had lower body weight fluctuation.

Methods: We used a previously validated algorithm (positive predictive value of 94%) to assemble a cohort of SLE patients from a de-identified version of an academic medical center’s electronic health record. We extracted outpatient weight measurements and reviewed cases with outlier values to confirm their accuracy. We excluded (1) patients with fewer than three visits or age less than 18 years at the time of the first relevant ICD9 code (710.0 for SLE), (2) weights from 90 days prior to and 270 days after an occurrence of pregnancy, and (3) weights measured during inpatient or emergency department visits. We then conducted a retrospective cohort study in which body weight fluctuation (measured as average successive variability) was analyzed to identify associations with demographic variables, clinical characteristics, and outcomes among SLE patients. We used a Poisson regression and adjusted for age, sex, race, and baseline Charlson comorbidity index in the multivariate analysis. The primary outcome was all-cause mortality.

Results: A total of 690 SLE patients met inclusion criteria. Patients with body weight fluctuation below the median were described as “low body weight fluctuation,” while patients with body weight fluctuation above the median were termed “high body weight fluctuation.” High body weight fluctuation correlated significantly with several baseline characteristics, including younger age, black race, and higher weight (Table 1). In the multivariate analysis, there was a significant association between body weight fluctuation and mortality (incidence rate ratio [IRR]: 2.009; 95% confidence interval [CI] 1.16-3.47; p = 0.012; Table 2).

Conclusion: In patients with SLE, high fluctuation in body weight, but not baseline BMI nor weight, was associated with increased mortality independent of age, race, sex, and baseline comorbidities. This association may indicate that early recognition by providers of weight fluctuation—even more than BMI or body weight—has the potential to decrease mortality in SLE patients.

Table 1

Table 2

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-association-of-body-weight-fluctuation-and-all-cause-mortality-in-patients-with-systemic-lupus-erythematosus/