Obesity, weight change and disease activity measures in patients with rheumatoid arthritis
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Citation
Abstract
BACKGROUND: Rheumatoid arthritis (RA) is an autoimmune disease that causes
inflammatory polyarthritis, typically of the small joints. Obesity, a serious global
epidemic, has been shown to increase systemic inflammatory biomarkers,
several of which are related to RA pathophysiology. Associations have been
observed between obesity and worsened RA disease activity outcomes in crosssectional studies. Limited longitudinal studies investigated the effects of weight
change on RA disease activity measures. Surgical interventions for weight loss in
RA patients showed marked improvement in RA disease activity measures and
outcomes but typical weight change in a clinical setting has not been
investigated.
OBJECTIVE: To investigate the impact of typical weight change on RA disease
activity measures.
METHODS: We conducted a retrospective cohort study on 178 RA patients seen in
typical clinical practice that met the inclusion criteria for the study, which included
patients with a minimum of two clinical disease activity assessments (CDAI) with
corresponding body mass index (BMI) measures. Medical record review was conducted for each clinic visit where CDAI and BMI were measured, and at each
of these visits, sociodemographic, lifestyle, medication usage, questionnaire
data, RA characteristics, laboratory values, and comorbidities were collected.
Linear regression was used to analyze the association between ΔBMI and
ΔCDAI, defined at the dates of minimum and maximum BMI for each subject,
adjusting for confounders including sex, age, disease duration, smoking status,
serologic status, and steroid usage. Logistic regression was performed to
evaluate whether ΔBMI was associated with low/remission RA disease activity
according to accepted CDAI cutoffs.
RESULTS: Unadjusted linear regression was performed on all 178 subjects to
analyze the overall trend within the sample population. For every 1 kg/m2
increase in BMI, CDAI increased by 0.49 points, but these results were not
statistically significant (p=0.155, 95%CI -0.176, 1.097). Subjects were stratified
into BMI gain, stable, and loss groups. Within the BMI loss group (defined as
those whose BMI decreased by more than 1 kg/m2), a significant association was
found with ΔCDAI (β= -2.61 [p=0.028, 95%CI -4.91, -0.298]). Unadjusted linear
regression on the BMI gain and stable groups was found to be not statistically
significant. This association remained significant after adjusting for sex, age,
disease duration, smoking status, serologic status, and steroid usage (β=-2.499
[p=0.044, 95%CI -4.94, -0.061]). There was no association between ΔBMI and
low/remission RA disease activity (OR 0.990, (95%CI 0.855, 1.146). When
stratified by BMI gain, stable, and loss groups there was no significant association with low/remission RA disease activity.
CONCLUSION: These results suggest that weight loss may be associated with
improved disease activity among patients with RA seen in a typical clinical
setting. Weight loss has the potential to be a non-pharmacologic intervention to
improve RA disease activity. Prospective studies of weight loss and RA disease
activity are necessary to replicate these results.