FRI0319 DO OBESITY AND OVERWEIGHT INFLUENCE DISEASE ACTIVITY MEASURES IN AXIAL SPONDYLOARTHRITIS? A SYSTEMATIC REVIEW AND META-ANALYSIS
Authors: A. Ortolan, M. Lorenzin, M. Felicetti, R. Ramonda
Journal: Annals of the Rheumatic Diseases (2020)

Background: obesity is apparently related with worse treatment response in axial spondyloarthritis (axSpA). However, it is unclear whether obesity or overweight per se are associated to higher disease activity scores compared to non-obese individuals, and what is the effect size of this difference. Objectives: to investigate whether overweight/obesity are associated to higher disease activity as measured by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) or Ankylosing spondylitis disease activity score (ASDAS) in axSpA patients. Methods: MEDLINE, PubMed and Web of Science were searched using key terms corresponding to population (axSpA), exposure (overweight/obesity) and outcome (BASDAI, ASDAS). Predefined inclusion criteria were: 1) adult axSpA patients, both radiographic and non-radiographic 2) exposure classified according to Body Mass Index-BMI-; 3) BASDAI/ASDAS reported for each BMI group; 4) observational studies. Patients classified according to CASPAR or Moll&amp;Wright criteria for psoriatic arthritis were excluded. Newcastle-Ottawa Scale for cohort, cross-sectional and case-control studies was used for quality check. BASDAI and ASDAS estimates were reported as mean difference (MD) and standard deviation (SD) between the normal BMI axSpA patients and the overweight or obese patients. The statistical heterogeneity of meta-analysis was assessed using the I 2 statistic. Random-effects meta-analysis was used to pool results. Results: A total of 330 references were generated by the database search. After removing duplicates, 250 references remained and were assessed for eligibility. A further 206 articles were excluded by titles and abstracts’ reading, 44 articles were examined full text. Only 11 articles fulfilled inclusion/exclusion criteria. Following quality check, 10 articles were finally included in the meta-analysis (Table). Among these, 4 studies reported two BMI groups (normal vs overwight+obese), while 6 studies reported three (normal, overweight, obese). In the studies reporting 3 BMI group, weighted means and standard deviation were calculated to create a merged overweight+obese group. The mean difference (MD) between pooled BASDAI and ASDAS of normal BMI patients and those of overweight+obese patients were respectively -0.38 (95%CI: -0.56, -0.21) and -0.19 (95%CI: -0.29, -0.09). In the articles reporting 3 BMI groups, the MD between BASDAI of normal BMI and overweight only patients was -0.09 (95% CI: -0.33; 0.15); between normal BMI and obese only patients MD was -0.77 (95%CI -1.07; -0.48, p&lt;0.0001) (Figure). Heterogeneity statistics revealed low estimates, though with wide CI across all the groups (Figure). Conclusion: disease activity scores of normal BMI axSpA patients tend to be lower than overweight or obese patients. However, this difference seems to be relevant in practice especially when normal BMI patients are compared to truly obese patients (BMI ≥ 30). Table. Charactheristics of studies included in the meta-analysis and of the studied patients Author and year Design Country N° of patients Age (years) Male sex HLAB27+ Disease duration (years) Al-Osami 2018 cohort Iran 170 36.1 (9.0) 158 (93) 68(40) 8.3 (5.9) Durcan 2012 cross-sectional Ireland 46 45.1(11.2) 35 (76) N/D 12.9 (10.9) Hernandez-Breijo 2019 cohort Spain/ Netherlands 180 47.0 (12.7) 107 (59) 131 (73) 8.0 (5.9) Lee 2017 cross-sectional China 194 38.7 (13.7) 150 (77) 159 (82) 7.1 (8.6) Maas 2016 cross-sectional Netherlands 461 45.3 (12.8) 303 (66) 361 (80) 17 (15.2) Micheroli 2017 cohort Switzerland 624 39.4 (11.6) 388 (62) 487 (78) 13 (10.9) O’Shea 2015 cross-sectional Ireland 267 47.8 (N/D) 212 (79) N/D 21.7 (N/D) Ottaviani 2012 cohort France 155 43.1 (12.4) 98 (63) 96 (65) 8.0 (4.8) Rosas 2017 cross-sectional Spain/ Mexico 57 47.1 (10.4) 37 (65) 44 (77) 9.8 (9.3) Rubio-Vargas 2016 cross-sectional Netherlands 168 30.2 (8.2) 81 (48.2) 156 (93) N/D Legend. Results are expressed as mean (SD) or number of patients (%). HLA= Human Leukocyte Antigen; N/D= not determined Disclosure of Interests: Augusta Ortolan: None declared, Mariagrazia Lorenzin: None declared, Mara Felicetti: None declared, Roberta Ramonda Speakers bureau: Novartis, Celgene, Janssen, Pfizer, Abbvie, Lilly