High BMI, Obesity Predict Worse Disease Outcomes in Axial Spondyloarthropathy

Obese man being measured by a doctor
Obese man being measured by a doctor
Recognition of the negative consequences of being obese is vital to effectively managing axial spondyloarthropathy.
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SAN DIEGO — Findings from a study presented at the ACR/ARHP 2017 Annual Meeting showed that higher body mass index (BMI) and obesity independently predicted worse disease outcomes in axial spondyloarthropathy (axSpA).

To examine the prevalence of obesity in a large population with axSpA, as well as to assess the association between obesity and disease outcomes, Gillian Fitzgerald, MB, MCh, MAO, MRCPI, from St. James’s Hospital in Dublin, Ireland, and colleagues enrolled 683 participants from the Ankylosing Spondylitis Registry of Ireland in this cross-sectional study (77% [n=526] male, 96% white, mean age 45.9 ± 12.4 years). The average delay to diagnosis was 8.6±8.1 years, and 78.8% of patients fulfilled modified New York criteria. Mean Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) was 3.9±2.5, mean Bath Ankylosing Spondylitis Metrology Index (BASMI) was 3.6±2.5, mean Bath Ankylosing Spondylitis Functional Index (BASFI) was 3.6±2.7, and mean Health Assessment Questionnaire (HAQ) score was 0.52±0.52.

All patients underwent clinical assessment and patient-reported data were acquired with structured interviews. BMI was categorized according to World Health Organization criteria: normal weight <25.0 kg/m2, overweight 25.0 to 29.9 kg/m2, and obese ≥30 kg/m2. Average cohort BMI was 27.8±5.3 kg/m2: 1.1% (n=7) were underweight, 31.6% (n=205) had normal BMI, 38.9% (n=252) were overweight, and 28.4% (n=184) were obese. 

The 67.3% of patients who were either overweight or obese were significantly older, had longer disease duration, and had more comorbidities — especially hypertension and hyperlipidemia — compared with patients of normal weight.

Obese patients had significantly higher disease activity (BASDAI [0-10]: 4.5 [±2.3] vs 3.7 [±2.5], P <.05), worse physical function (BASFI [0-10]: 4.6 [±2.6] vs 2.9 [±2.5], P <.05), spinal mobility (BASMI [0-10]: 4.6 [±2.5] vs 3 [±2.3], P <.05), and quality of life (ASQoL [0-18] 8 [±5.4] vs 6 [±5.5]) compared with patients of normal weight.

In univariable linear regression, BMI and obesity were associated with higher BASDAI, ASQoL, BASMI, BASFI, and HAQ scores. In multivariable regression analysis, obesity remained an independent predictor of higher disease activity and worse function.

“In conclusion, this study shows that high BMI is prevalent in an Irish axSpA population, with over 2/3 of the cohort being either overweight or obese. Being obese with axSpA predicts more severe disease, as obese patients have worse disease outcomes than their overweight and healthy weight counterparts,” Dr Fitzgerald said. “Prospective studies would be very useful to further clarify these relationships, and in particular, to investigate the effect of weight loss on clinical outcomes.”

“However, it is imperative that clinicians are aware of the negative consequences of being obese [on] axSpA. When devising treatment plans for axSpA patients, this study provides rheumatologists with a strong rationale to increase strategies to actively control weight,” she concluded.

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When questioned on interventions in overweight or obese patients with rheumatologic disorders, 2 researchers who were not part of this study but who study obesity and rheumatologic disease, offered additional comments. Stefano Alivernini, MD, PhD, from the Institute of Rheumatology at the Catholic University of The Sacred Heart in Rome, noted that a multidisciplinary approach would be necessary. Elena Nikiphorou, MBBS/BSc, MRCP, MD, PGCME, FHEA, from the Academic Rheumatology Department of King’s College London and the Whittington Hospital in London, said, “It is a vicious circle in the population of people we take care of. Musculoskeletal disease, obesity; one really drives the other … [A] next step we also want to focus on [is], what is the best strategy to address obesity? [Is that] in the form of exercise or special diet? I think nutrition is something that is very much ignored in rheumatic musculoskeletal diseases.”

Disclosures: Oliver FitzGerald reports relationships with Pfizer, Abbvie, BMS, Novartis, UCB, Janssen, Celgene, and Lilly.

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Fitzgerald G, Gallagher P, Sullivan C, et al. Obese axial spondyloarthropathy patients have worse disease outcomes. Presented at: ACR/ARHP 2017 Annual Meeting; November 3-8, 2017; San Diego, CA. Abstract 2508.