How Does Shame Relate to Clinical and Psychosocial Outcomes in Knee Osteoarthritis?

Background Knee osteoarthritis (OA) is a common and disabling condition that often carries severe psychosocial implications. Chronic illness–related shame has emerged as a substantial psychosocial factor affecting individuals with knee OA, but it is unclear how chronic illness–related shame is associated with the long-term clinical and psychosocial outcomes in individuals with knee OA. Questions/purposes (1) Does a higher level of shame correlate with worse clinical and psychosocial outcomes at baseline among individuals with knee OA? (2) Is a higher level of shame at baseline associated with worse clinical and psychosocial outcomes at 4-month and 12-month follow-up among individuals with knee OA? (3) Are sociodemographic characteristics correlated with levels of shame among individuals with knee OA? Methods Between June 2021 and February 2022, we screened 977 patients based on the inclusion criteria of (1) age 45 years or older, (2) independent in community mobility with or without walking aids, (3) proficient in English or Chinese language, and (4) met the clinical criteria for OA diagnosis outlined by the National Institute for Health and Care Excellence. Of these patients, 47% (460) were eligible and enrolled. A further 53% (517) were excluded for prespecified reasons. Of the 460 enrolled patients, 7% (30) dropped out before data collection began, and 46% (210) of patients did not complete the psychological questionnaires, leaving 48% (220) of patients for analysis. From this final sample, 25% (56) were lost to follow-up at 4 months, and an additional 7% (16) were lost by the 12-month follow-up, leaving 67% (148) of the original eligible group for analysis. All patients were recruited from the outpatient clinics of the orthopaedic and physiotherapy departments across two Singapore hospitals within the National Healthcare Group. The study population had a mean ± SD age of 64 ± 8 years, with 69% (152 of 220) women, and the mean ± SD duration of knee OA symptoms was 6 ± 6 years. Outcome measures used were the Chronic Illness-Related Shame Scale (CISS), the 12-item Knee Injury and Osteoarthritis Outcome Score (KOOS-12), Patient Health Questionnaire 4 (PHQ-4), the 8-item Arthritis Self-Efficacy Scale (ASES-8), and the Brief Fear of Movement Scale (BFOM). The CISS is a validated tool specifically designed to measure feelings of shame (internal and external shame) in individuals living with chronic illness. The scale has been validated for use among patients with knee OA in Singapore. The functional outcome measure used was the Modified Barthel Index. Data on demographic characteristics were collected. Data were collected at baseline, 4-month follow-up, and 12-month follow-up. Statistical analyses included the Spearman correlation, linear regression, and cluster analysis. Results At baseline, there was a weak to moderate negative correlation between CISS scores and KOOS-12 and ASES-8 scores (Spearman correlation coefficients ranged from -0.46 to -0.36; all p values < 0.001), indicating that higher levels of shame were associated with slightly to moderately worse knee function and lower self-efficacy. There was a modest positive correlation between CISS scores and PHQ-4 and BFOM scores (the Spearman correlation coefficients ranged from 0.43 to 0.46; all p values < 0.001), indicating that higher levels of shame were linked to more psychological distress and greater fear of movement. At the 4-month follow-up, a higher CISS score at baseline was associated with a decrease in KOOS-12 (adjusted coefficient -0.86 [95% confidence interval (CI) -1.33 to -0.40]; p < 0.001) and ASES-8 (adjusted coefficient -0.12 [95% CI -0.19 to -0.06]; p < 0.001) scores, indicating worsened knee function and reduced self-efficacy over time. Higher CISS scores at baseline were also associated with an increase in PHQ-4 (adjusted coefficient 0.23 [95% CI 0.14 to 0.31]; p < 0.001) and BFOM (adjusted coefficient 0.22 [95% CI 0.08 to 0.36]; p = 0.002) scores at the 4-month follow-up, reflecting greater psychological distress and greater fear of movement. At the 12-month follow-up, a higher CISS score at baseline was associated with a decrease in KOOS-12 (adjusted coefficient -0.72 [95% CI -1.25 to -0.19]; p = 0.008) and ASES-8 (adjusted coefficient -0.12 [95% CI -0.20 to -0.04]; p = 0.002) scores, indicating that those with higher initial levels of shame continued to experience poorer knee function and lower self-efficacy. Higher CISS scores at baseline were also associated with an increase in PHQ-4 (adjusted coefficient 0.13 [95% CI 0.04 to 0.21]; p = 0.004) as well as BFOM (adjusted coefficient 0.20 [95% CI 0.06 to 0.34]; p = 0.007) scores at the 12-month follow-up, indicating ongoing psychological distress and fear of movement. Cluster analysis found that unemployed older patients with lower CISS scores and BMI, as well as having unilateral arthritis and shorter duration of OA, were observed to have better knee function at 4 months (mean difference 7 [95% CI 1 to 12]; p = 0.02) and 12 months (mean difference 7 [95% CI 1 to 13]; p = 0.02) compared with the opposite. After controlling for age, gender, ethnicity, and employment status, the regression analysis found that higher BMI was related to higher CISS scores (adjusted coefficient 0.21 [95% CI 0.07 to 0.34]; p = 0.003). Conclusion Chronic illness–related shame has a small to modest association with clinical and psychosocial outcomes for individuals with knee OA. Healthcare professionals should routinely incorporate psychosocial assessments to identify and manage shame early, potentially improving both clinical and psychosocial outcomes. Recognizing that higher BMI is linked to increased shame can specifically guide targeted emotional and psychosocial support. Additionally, integrating interventions such as acceptance and commitment therapy and peer support with traditional treatments could enhance adherence and overall patient outcomes, making comprehensive care more effective. Level of Evidence Level II, prognostic study.