Background Functional disability, usually measured using the Health Assessment Questionnaire (HAQ), is a key outcome in patients with rheumatoid arthritis (RA). The influence of body mass index (BMI) on disease outcomes such as disability in RA is unclear. Obesity, (BMI ≥30kg/m2), is a recognised cause of chronic disability in the general population and has been to be associated with poor functional outcome in established RA. It is unknown whether this is also the case in early inflammatory polyarthritis (IP). With the rising prevalence of obesity worldwide, any such association will be increasingly important when trying to achieve optimal outcomes for RA patients.
To describe the prevalence of obesity in an inception cohort of patients with early IP
To investigate the influence of BMI on functional disability at baseline and after 1 year
Methods Patients age ≥16 with ≥2 swollen joints for ≥4 weeks were recruited into the Norfolk Arthritis Register (NOAR) between 2000 and 2009. Baseline clinical and demographic data were obtained through a standard questionnaire administered by a research nurse who also examined the joints and measured height and weight. Blood samples were taken for CRP, rheumatoid factor and anti-ccp antibody estimation. Patients completed the HAQ. Follow up at 1 year included repeat examination and HAQ. Univariate and multivariate ordinal regression were used to examine the influence of initial BMI on HAQ at baseline and after 1 year.
Results 887 patients were studied. 585 (66%) were female, mean age (SD) 56 (14) years. At baseline 61 (20%) men and 180 (30%) women were obese; 147 (49%) men and 188 (33%) womene were overweight. Obesity was associated with worse functional outcome in NOAR both cross-sectionally at baseline and in longitudinal analysis. This association was independent of age, gender, smoking status, disease activity score (DAS28), autoantibodies and number of comorbidities. There was no association between being overweight and functional disability
Conclusions This study has shown that obesity (and not overweight) at baseline is associated with an increased likelihood of higher HAQ group both at baseline and one year later, independent of disease activity. This relationship should be taken into account when interpreting HAQ in clinical practice.
Disclosure of Interest None Declared