Background The influence of body mass index (BMI) on disease activity or risk for complication in patients with rheumatoid arthritis (RA) is unclear.
Objectives To investigate the influences of BMI on disease activity, risk for hospitalization, and joint destruction in patients with RA using data of NinJa (National Database of Rheumatic Diseases by iR-net in Japan) in 2010.
Methods A total of 3,255 RA patients (2,631 women and 624 men; mean age, 63.1 yr; disease duration, 13.1 yr; height/body weight/BMI, 153.2 cm/50.9 kg/21.7 kg/m2 in women and 165.7 cm/61.6 kg/22.4k g/m2in men) were included in the analyses. They were categorized by BMI as follows; Group A (underweight): <18.5 kg/m2, Group B (normal): 18.5-24.9 kg/m2, Group C (overweight): 25.0-29.9 kg/m2, Group D (obese): ≥30.0 kg/m2, and their composite disease activity indices (DAS28-ESR), their components and other markers (TJC, SJC, PtGA, PtPain, PhGA, mHAQ, CRP, ESR), incidence of hospitalization in 2010, and past history of joint arthroplasty were compared in a gender-specific manner.
Results Women were younger (62.9 yr), had longer disease duration (14.0 yr), and higher SDAI scores (9.0) than men (65.2 yr, 9.6 yr, and 8.8). The mean SDAI scores were highest in Group A in both women and men. SDAI scores decreased gradually from Group A to D in men. Similarly, in women the scores decreased from A to C, but increased again in Group D (mean SDAI: Group A: 12.2, B: 8.9, C: 6.9, D: 4.0 in men, and A: 11.2, B: 8.6, C: 8.5, D: 10.6 in women).
Mean numbers or values of each component showed almost similar trends to SDAI scores. In both women and men, incidence rate of hospitalization was highest in Group A (23.3% in women and 25.5% in men) and the following was in Group D (20.7% and 25.0%), but decreased in Group C (16.1% and 19.7%) and D (17.6% and 17.8%). Similar trends were observed in the rate of past history of joint arthroplasty.
Conclusions Being underweight appears to be associated with high disease activity and risk for hospitalization in patients with RA.
Disclosure of Interest None Declared