Background/Purpose: Obesity is a growing problem in Western society. It is associated with an increased risk for many disorders, impaired functional capacity, and impaired quality of life (QoL). The aim of the present study was to evaluate the prevalence of overweight and obesity and the relation with clinical assessments of disease activity, physical function, and QoL in patients with axial spondyloarthritis (SpA).

Methods: 465 consecutive patients from the Groningen Leeuwarden Axial SpA (GLAS) cohort who visited the outpatient clinic between January 2011 and December 2012 were included in this cross-sectional analysis. All patients fulfilled the modified New York criteria for ankylosing spondylitis (AS) (>90%) or the ASAS criteria for axial SpA. Body mass index (BMI) was calculated and patients were divided into groups according to the WHO criteria: low BMI (BMI <18.5 kg/m²), normal BMI (BMI 18.5-25 kg/m²), overweight (BMI 25-30 kg/m²), and obesity (BMI >30 kg/m²). Disease activity was assessed by Bath AS Disease Activity Index (BASDAI), AS Disease Activity Score (ASDAS), and C-reactive protein (CRP), physical function by Bath AS Functional Index (BASFI), and quality of life by ASQoL questionnaire.

Results:  Mean age of the 465 patients was 45 years (SD±13), median symptom duration was 17 years (range 0-61), 65% were male, and median BMI was 26.0 kg/m² (range 17.0-45.4). In total, 8 (2%) patients had low BMI, 183 (39%) had normal BMI, 174 (37%) were overweight, and 100 (22%) were obese. Of the 100 obese patients, 19 had BMI between 35-40 kg/m² and 3 had BMI >40 kg/m². In comparison, the general Dutch population aged 30-70 years and matched for gender had an estimated prevalence of 1% low BMI, 44% normal BMI, 42% overweight, and 13% obesity.¹

Obese axial SpA patients were significantly older, had longer disease duration, and more comorbidity than patients with normal BMI. Disease activity of obese patients was significantly higher and physical function and QoL were significantly worse compared to patients with normal BMI (Table 1). These differences remained statistically significant after correcting for age, disease duration, and comorbidity. No significant differences in clinical assessments were found between patients with overweight and normal BMI (Table 1).

Conclusion:  In this large cohort of axial SpA patients with relatively longstanding disease, almost a quarter of the patients were obese. Cross-sectional analysis shows that the presence of obesity was associated with higher disease activity and worse physical function and QoL.

References: 1. Rijksinstituut voor Volksgezondheid en Milieu (2012). Available at: www.rivm.nl.

Table 1. Disease activity, physical function, and QoL of axial SpA patients with overweight and obesity compared to those with normal BMI.

	Normal BMI [18.5-25] (n=183)	Overweight BMI [25-30] (n=174)	P-value*	Obesity BMI [>30] (n=100)	P-value*
BASDAI (range 0-10)	3.4 (0-9.2)	3.5 (0-9.6)	0.235	4.4 (0.6-9.4)	0.029
ASDAS(CRP)	2.1 (0-5.2)	2.1 (0.3-5.1)	0.983	2.7 (0.5-5.7)	0.000
CRP (mg/L)	3.0 (0-73)	3.0 (0-94)	0.372	5.0 (0-82)	0.000
CRP ≥5 mg/L	62 (34)	56 (32)	0.795	53 (53)	0.001
BASFI (range 0-10)	2.9 (0-9.1)	2.7 (0-9.9)	0.635	5.1 (0.1-9.7)	0.000
ASQoL (range 0-18)	5.0 (0-17)	4.0 (0-18)	0.077	8.0 (0-18)	0.002

Values are presented as median (range) or number of patients (%). *P-values compared to patients with normal BMI.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-of-overweight-and-obesity-and-the-relation-to-disease-activity-physical-function-and-quality-of-life-in-patients-with-axial-spondyloarthritis/