TBA (17A112)

Obesity predicts worse disease outcomes in axial spondyloarthropathy patients

Author(s)

Fitzgerald G1, Gallagher P2, O Sullivan C3, O Rourke K4, Sheehy C5, Stafford F6, Silke C7, Haroon M8, Mullan R9, Fraser A10, Murphy G11, Chavrimootoo S12, FitzGerald O2, O Shea F1

 

Department(s)/Institutions

1. St James’s Hospital 2. St Vincent’s Hospital 3. University Hospital Galway 4. Midlands Regional Hospital Tullamore 5. University Hospital Waterford 6. Blackrock Clinic 7. Sligo General Hospital 8. Kerry General Hospital 9. Tallaght Hospital 10. University Hospital Limerick 11. Cork University Hospital 12. Our Lady’s Hospital, Navan.

Introduction

Obesity is a worldwide public health concern, due to its association with morbidity and mortality. Existing literature looking at obesity in axial spondyloarthropathy (axSpA) is sparse, but indicates increased BMI is prevalent. The impact of obesity on disease outcome is less well known. 

Aims/Background

We aimed to determine the prevalence of obesity in a large axSpA cohort and describe its association with disease outcomes.

Method

Ankylosing Spondylitis Registry of Ireland (ASRI) provided the cohort for this study. A standardised clinical assessment is performed on each patient. Structured interviews provide patient-reported data. Weight is recorded in kilograms (kg) and height in centimetres (cm). BMI is categorised per the World Health Organisation criteria: normal weight <25 kg/m2, overweight 25-29.9 kg/m2 and obese ≥ 30 kg/m2. Disease activity is assessed by Bath AS Disease Activity Index (BASDAI), spinal mobility by Bath AS Metrology Index (BASMI), function by the Bath AS Functional Index (BASFI) and Health Assessment Questionnaire (HAQ) and quality of life by AS Quality of Life (ASQoL). SPSS is used for statistical analysis.

Results

As of June 2017, 683 patients have been enrolled: 77% (n=526) male, mean age 45.9 ± 12.4 years, mean disease duration 19±12.2 years, mean delay to diagnosis 8.6±8.1 years, 78.8% fulfil modified New York criteria. Mean BASDAI is 3.9±2.5, BASMI is 3.6 ± 2.5, BASFI is 3.6± 2.7 and HAQ is 0.52 ±0.52.

Mean BMI in the cohort is 27.8±5.3 kg/m2: 1.1% (n=7) underweight, 31.6% (n=205) normal BMI, 38.9% (n=252) overweight, 28.4% (n=184) obese. Overall, 67.3% are overweight or obese: these patients are significantly older, have longer disease duration and more comorbidity than normal weight patients (table 1). Obese patients have significantly higher disease activity and worse physical function, spinal mobility and quality of life than both normal weight and overweight patients. The prevalence of smoking is lower in obese patients than normal weight patients. In univariable linear regression, BMI and obesity are associated with higher BASDAI, ASQoL, BASMI, BASFI and HAQ scores (table 2). In multivariable regression analysis, obesity remains an independent predictor of higher disease activity and worse function.

Conclusions

Over two thirds of this axSpA cohort is overweight or obese. Higher BMI and obesity independently predicts worse disease outcomes. Strategies should be put in place to actively reduce axSpA patient’s BMI.

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