Physical function and sex differences in radiographic axial spondyloarthritis: a cross-sectional analysis on Bath Ankylosing Spondylitis Functional Index

BACKGROUND

Physical function is an important determinant of health-related quality of life in radiographic axial spondyloarthritis patients (r-axSpA). To improve the basis of effective healthcare efforts, we aimed to investigate which demographic and disease-related factors that influence Bath Ankylosing Spondylitis Functional Index (BASFI) in r-axSpA patients overall and stratified by sex. Furthermore, we sought to explore differences between sexes regarding separate BASFI questions and also to explore which factors that may contribute to these differences.

METHODS

This observational cross-sectional study included patients fulfilling the modified New York criteria for Ankylosing Spondylitis. Patients were assessed with 66/68 joint count and Bath Ankylosing Spondylitis Metrology Index (BASMI) measurements. Lateral X-rays were performed for Modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS)-C-Reactive Protein (CRP), and BASFI were registered. Multivariable linear regression analyses were used to investigate which factors that associate with BASFI.

RESULTS

A total of 353 r-axSpA patients were included, mean age 52.2 ± 12.7 years, 62.3% males. No significant sex difference was seen in BASFI scores (2.7 ± 2.0 in males vs 2.9 ± 2.1 in females). Age, body mass index, ASDAS-CRP, BASMI or mSASSS, fatigue, and tenderness were found to associate independently with BASFI in different models (R2 0.53-0.63). Investigation of separate BASFI questions revealed that the ability to look over shoulder was worse in males than females (mean 4.43 ± 3.37 vs 3.74 ± 3.06, p = 0.05) and most strongly correlated with mSASSS and BASMI among separate BASFI questions (r = 0.53, p < 0.001; r = 0.62, p < 0.001). The ability to climb stairs was worse in females than males (mean 2.49 ± 2.77 vs 1.54 ± 2.32, p < 0.001).

CONCLUSIONS

No difference between male and female r-axSpA patients was seen in BASFI despite significant sex differences in BASMI, mSASSS, and CRP levels. Our results underline the impact of fatigue and tenderness on BASFI. The ability to climb stairs without a handrail was scored worse among females compared to males. Furthermore, the ability to look over the shoulder was worse in males than females and closely related to spinal mobility and structural spinal changes.

Patients with radiographic axial spondylarthritis have an impaired dietary intake-a cross-sectional study with matched controls from northern Sweden

BACKGROUND

Radiographic axial spondyloarthritis (r-axSpA) is one of the most common chronic inflammatory rheumatic diseases, affecting about 0.2% of the Swedish population. Adequate nutritional intake is essential for maintaining physiological functions. A poor diet increases the risk of developing conditions such as obesity, osteoporosis, and/or atherosclerosis. Diet quality is also theorized to affect systemic inflammation. Dietary habits in patients with r-axSpA are largely unknown. The aims of this study were to assess dietary nutrient intake in r-axSpA patients and examine whether it differs compared to persons without r-axSpA.

METHODS

r-axSpA patients (modified NY criteria) at the rheumatology clinic in Region Västerbotten, northern Sweden, were invited to take part in the Backbone study which investigates disease severity and comorbidities. In total, 155 patients were included. Nutritional intake was assessed by the semi-quantitative food frequency questionnaire MiniMeal-Q. Controls were collected from the Swedish CArdioPulmonary bioImage Study (n = 30,154), a study that invited participants 50-64 years of age by random selection from the Swedish population register. Out of the 155 r-axSpA patients, 81 were in the same age span. Four controls were identified for each patient, matched on age (± 1 year), sex, and geographic location. Data on dietary intake was available for 319 controls. Statistical comparisons of dietary intake between patients with r-axSpA and controls were done by exact conditional logistic regression analysis, adjusted for country of birth, educational level, single household, weight, smoking status, and energy intake.

RESULTS

Patients had a comparatively significantly higher energy intake from carbohydrates, a lower fiber density, and a lower intake of marine omega-3 fatty acids. Furthermore, intake of vitamins D, E, and K as well as selenium, folate, calcium, magnesium, phosphorus, potassium, vitamin A, and β-carotene (a precursor of vitamin A and marker of vegetable and fruit intake) was significantly lower among patients compared to controls.

CONCLUSIONS

Our results suggest that r-axSpA patients have an impaired dietary intake. Notably, intake was lower in several nutrients theorized to have anti-inflammatory properties (fiber density, marine-omega-3 fatty acids, vitamin D, and selenium). We further propose that nutrition screening might be incorporated into the management of r-axSpA patients.