Background Knowledge about the impact of illness perceptions on Health-Related Quality of Life (HRQoL) in patients (pts) with axial Spondyloarthritis (axSpA) and other forms of chronic back pain (CBP) is lacking.
Objectives To explore the association between illness perceptions and HRQoL in pts with short symptom duration of axSpA and other forms of CBP at baseline.
Methods The Spondyloarthritis Caught Early (SPACE) study includes pts with CBP (≥3 months, ≤2 years, onset <45 years) recruited from 5 European centres. The Revised Illness Perception Questionnaire (IPQ-R) was completed at baseline. In the illness identity dimension, pts reported if they have experienced and believed that a certain symptom is CBP related. Other illness perceptions and causal dimensions used 5-point Likert scales (1 strongly disagree, 5 strongly agree). HRQoL was assessed by 36-item Short-Form (SF-36). Scale scores ranged from 0 (worst) to 100 (best). Physical (PCS) and Mental Component Summary (MCS) scores were calculated. Univariable regression models were built for each IPQ-R subscale as independent and PCS or MCS as dependent variable. The models were adjusted for age and gender and stratified in case of effect modification by gender (p<0.10).
Results 315 pts were included; 123 fulfilled axSpA ASAS criteria and 192 did not fulfil the criteria. Mean age was 31.3 (SD 8.3) years, mean duration of CBP was 13.2 (SD 7.2) months and 36.5% was male. Mean PCS was 28.0 (SD 16.3) for axSpA pts and 24.9 (SD 14.4) for CBP. As the MCS was only slightly decreased compared to the general population (48.0 (SD 13.3) axSpA and 49.7 (SD 11.5) CBP pts), analyses focused on PCS. Pts reported a mean of 4.3 (axSpA) and 4.8 (CBP) symptoms to be associated with back pain. Most reported symptoms were pain and joint stiffness. All other subscales showed a mean of approximately 3, except psychological attributions, risk factors, immunity and accident (mean approximately 2). All pts attributed their complaints mostly to genetic factors. In both pts groups attribution of multiple symptoms to CBP (Figure 1;-1.8 axSpA, -2.1 CBP) was associated with lower PCS. However more dimensions showed association with PCS in axSpA (8) than CBP pts (6). In male axSpA pts belief in severe consequences (-12.1), more negative emotions towards their complaints (-9.3), and stronger belief of psychological attributions as a cause (-8.8) were associated with lower PCS. Whereas in male CBP pts stronger belief in risk factors (-8.1) and immunity as a cause (-10.0) were associated with lower PCS. More illness coherence was associated with higher PCS in male axSpA (6.2) and all CBP pts (2.8). In women consequences (-6.3, axSpA) and strong emotional representations (-4.0, CBP) were statistically significant. No gender differences were found for risk factors (-6.0) or immunity (-5.7) in axSpA and consequences (-7.9) in CBP pts.
Conclusions Negative illness perceptions are associated with lower PCS of HRQoL in pts with axSpA and other forms of CBP. The impact of negative illness perceptions on PCS was more pronounced in men than in women.
Disclosure of Interest None declared