Cyrille Burrus

Introduction: The effects of pain medication on physical performance in chronic pain are poorly understood. We examined the association between analgesics and physical performance in people with chronic musculoskeletal pain (CMSP) requiring rehabilitation. Methods: We classified participants into 3 categories according to the highest level of medication used at admission for rehabilitation: no analgesics (NAs), nonopioid analgesics (NOAs), and opioid analgesics (OPAs). We measured performance with functional tests (6-minute walk test [6MWT], progressive isoinertial lifting evaluation [PILE], steep ramp test, handgrip strength test [HST], 5 times sit-to-stand test, and 1-minute stair-climbing test [1MSCT]) at admission and discharge. Multiple regression models were used to assess the differences in functional capacity between the 3 groups, adjusting for potential confounders. Results: We included 4,339 individuals; 1,731 took no analgesics (40%), 1,742 took NOAs (40%), and 866 took OPAs (20%). The median consumption was 11.7 mg per day according to morphine-equivalent dose calculation. Physical performance was poorer for patients taking than those not taking analgesics in all tests examined. We found a negative gradient in performance with increasing WHO analgesic ladder. The odds of achieving clinically significant improvements in 4 tests (6MWT, PILE, HST affected side, and 1MSCT) was reduced for people taking opioids compared with the NA group. Conclusion: Given the inconclusive and limited evidence for the benefit of analgesics on pain and disability in CMSP, health professionals should be aware of these results for even low doses of opioids, which were associated with poor physical performance and rehabilitation progress.

Introduction: Opioid prescription is associated with various biopsychosocial (BPS) domains. Explaining how they interact is worth to better understand their role. Objectives: To assess direct and indirect effects of BPS complexity and pain-related factors on opioid prescription in patients with chronic musculoskeletal pain. Methods: We included 3,923 individuals admitted to a tertiary care rehabilitation clinic. Two outcomes were defined: likelihood of opioid prescription at admission (yes/no) and daily morphine equivalent dose (dMED) during rehabilitation. Predictors were sociodemographic factors, injury severity and location, pain-related factors (pain catastrophizing, depressive symptoms, pain severity), and BPS complexity assessed by the INTERMED method. Structural equation modelling was used to assess the direct and indirect effects of BPS complexity on outcomes. Results: Biopsychosocial complexity had a direct effect on opioid prescription (OR 1.20; 95% CI 1.10–1.32) and indirect effects via pain severity (OR 1.09; 95% CI 1.06–1.12) and depressive symptoms (OR 1.02; 95% CI 1.00–1.04). Biopsychosocial complexity also had direct effect on dMED (β = 1.17, 95% CI 1.06–1.28) and an indirect effect via pain severity (exp β = 1.03; 95% CI 1.00–1.07). Pain catastrophizing was indirectly associated with opioid prescription and dose via pain. The likelihood of opioid prescription was associated with female sex, increased education level, and spine trauma; the latter 2 factors were also associated with increased dMED. Conclusion: Our study suggests that BPS complexity is associated with opioid prescription and dose, with direct and indirect effects via pain severity or depressive symptoms. Screening and addressing patients' complexity may help decrease opioid prescriptions and risk of misuse.

Purpose: To assess and compare the healthcare costs, time to fitness for work (TFW) between chronic complex regional pain syndrome (CRPS) and non-CRPS; and identify factors associated with these outcomes in a comparative longitudinal study. Patients and Methods: 148 patients with chronic CRPS of the hand and 273 patients with chronic hand impairments but without CRPS (non-CRPS) were admitted at a Swiss rehabilitation clinic between 2007 and 2016. Healthcare costs and TFW were retrieved from insurance data over 5 years after the accident. Socio-demographic factors, biopsychosocial complexity measured by means of the INTERMED questionnaire, pain intensity and DASH disability scores were collected during rehabilitation. Generalized estimation equations and Cox proportional-hazards models were used to identify factors associated with outcomes. Results: Healthcare costs were increased by 20% for the CRPS versus non-CRPS group (coefficient = 1.20, 95% CI = 1.08-1.35, p<0.001). The median TFW was longer for CRPS than non-CRPS patients (816 vs 672 days, p = 0.02). After adjusting for covariates, TFW did not differ between the two groups (hazard ratio = 0.94, 95% CI = 0.73-1.21, p=0.61). For CRPS patients, higher healthcare costs were associated with severe or moderate initial injury, high INTERMED or DASH disability scores. Longer TFW were associated with severe initial injury, low educational level, no work contract, and high INTERMED or DASH disability scores. Conclusion: Overall, the healthcare costs were higher for CRPS than non-CRPS patients, but the TFW was comparable. We demonstrated also the significant associations of disability and biopsychosocial factors with the healthcare costs and TFW in CRPS patients.

Purpose: Chronic pain is a complex phenomenon. Understanding its multiple dimensions requires the use of a combination of several patient-reported outcome measures (PROMs). However, completing multiple PROMs is time-consuming and can be a burden for patients. The objective of our study was to simultaneously reduce the French versions of the Pain Catastrophizing Scale (PCS) and Tampa Scale for Kinesiophobia (TSK) questionnaires to enable their use in an ambulatory and clinical settings. Patients and Methods: We conducted a clinical study between May 2014 and August 2020 in our rehabilitation center. 1428 chronic musculoskeletal pain patients (CMSP) were included. The originality of our approach is that the reduction method included qualitative as well as quantitative analyses. The study was divided into two parts: 1) reduction of the questionnaires (n=1363) based on internal consistency (item-to-total correlation), principal component analysis (item loadings), Rasch analysis (infit/outfit), floor and ceiling effect (quantitative analyses) and expert judgment of items (qualitative analysis), and 2) validation of the reduced questionnaires (n=65), including test–retest reliability (intraclass correlation coefficient [ICC]), homogeneity (Cronbach α), criterion validity (Pearson correlation [r] with the long-version score), determination of the pathological cutoff and Minimal Clinically Important Difference (MCID). The two full-length questionnaires include 30 items in total. Results: The reduction resulted in a 5-item PCS (score 0– 20) and 6-item TSK (score 0– 24). Psychometric properties of the reduced questionnaires were all acceptable as compared with other version (α=0.89 and 0.71, ICC=0.75 and 0.60, r=0.86 and 0.70, MCID=2 and 2 for PCS and TSK, respectively) while keeping the structure and coherence of the long versions. Conclusion: The two reduced versions of the PCS and TSK can be used in CMSP patient. As their administration only requires a few minutes, they can be implemented in outpatient consultation as well as in clinical settings.

Purpose To determine the levels of perceived work demand capacity corresponding to the Modified Spinal Function Sort (M-SFS) score and precise reliability validity and responsiveness. Methods This prospective validation study included patients with chronic musculoskeletal impairments who underwent multidisciplinary occupational rehabilitation. After determining the percentiles of the work demand thresholds corresponding to the spinal function sort (SFS), the percentiles were transposed to the M-SFS. Reliability was assessed using the intraclass correlation coefficient and limits of agreement. Correlations with other questionnaires and a lifting task were measured to assess validity. Responsiveness was determined using anchor- and distribution-based approaches. Results 288 patients were included. The following thresholds were obtained for the M-SFS: 0–43 points, minimal; 44–50, very light; 51–58, light; 59–64, light to medium; 65–70, medium; 71–76, heavy; and 77–80, very heavy. Reliability was confirmed. The correlation between the M-SFS and SFS scores was good at 0.89 (95% CI, 0.86–0.91) and moderate according to the PILE-test result of 0.60 (95% CI, 0.50–0.67). We could not calculate a valid anchor-based minimal clinically important difference. The standard error of measurement was 3.9 points, and the smallest detectable change was 10.8 points. Conclusions On the basis of the comparison of the M-SFS and SFS scores, the M-SFS score can be interpreted in relation to the levels of work demand. This study confirms the good reliability and validity of the M-SFS questionnaire in assessing perceived physical capacity. Further studies are needed to determine its responsiveness.

Purpose: To compare the prevalence of psychiatric comorbidity between patients with complex regional pain syndrome (CRPS) of the hand and non-CRPS patients and to assess the association between biopsychosocial (BPS) complexity profiles and psychiatric comorbidity in a comparative study. Patients and Methods: We included a total of 103 patients with CRPS of the hand and 290 patients with chronic hand impairments but without CRPS. Psychiatric comorbidities were diagnosed by a psychiatrist, and BPS complexity was measured by means of the INTERMED. The odds ratios (OR) of having psychiatric comorbidities according to BPS complexity were calculated with multiple logistic regression (adjusted for age, sex, and pain). Results: Prevalence of psychiatric comorbidity was 29% in CRPS patients, which was not significantly higher than in non-CRPS patients (21%, relative risk=1.38, 95% CI: 0.95 to 2.01 p=0.10). The median total scores of the INTERMED were the same in both groups (23 points). INTERMED total scores (0– 60 points) were related to an increased risk of having psychiatric comorbidity in CRPS patients (OR=1.46; 95% CI: 1.23– 1.73) and in non-CRPS patients (OR=1.21; 95% CI: 1.13– 1.30). The four INTERMED subscales (biological, psychological, social, and health care) were correlated with a higher risk of having psychiatric comorbidity in both groups. The differences in the OR of having psychiatric comorbidity in relation to INTERMED total and subscale scores were not statistically different between the two groups. Conclusion: The total scores, as well as all four dimensions of BPS complexity measured by the INTERMED, were associated with psychiatric comorbidity, with comparable magnitudes of association between the CRPS and non-CRPS groups. The INTERMED was useful in screening for psychological vulnerability in the two groups.

Objective: To use the self-assessment INTERMED questionnaire to determine the relationship between biopsychosocial complexity and healthcare and social costs of patients after orthopaedic trauma. Design: Secondary prospective analysis based on the validation study cohort of the self-assessment INTERMED questionnaire. Setting: Inpatients orthopaedic rehabilitation with vocational aspects. Subjects: In total, 136 patients with chronic pain and impairments were included in this study: mean (SD) age, 42.6 (10.7) years; 116 men, with moderate pain intensity (51/100); suffering from upper ( n = 55), lower-limb ( n = 51) or spine ( n = 30) pain after orthopaedic trauma; with minor or moderate injury severity (severe injury for 25). Main measures: Biopsychosocial complexity, assessed with the self-assessment INTERMED questionnaire, and other confounding variables collected prospectively during rehabilitation. Outcome measures (healthcare costs, loss of wage costs and time for fitness-to-work) were collected through insurance files after case settlements. Linear multiple regression models adjusted for age, gender, pain, trauma severity, education and employment contract were performed to measure the influence of biopsychosocial complexity on the three outcome variables. Results: High-cost patients were older (+3.6 years) and more anxious (9.0 vs 7.3 points at HADS-A), came later to rehabilitation (+105 days), and showed higher biopsychosocial complexity (+3.2 points). After adjustment, biopsychosocial complexity was significantly associated with healthcare (ß = 0.02; P = 0.003; exp^ß = 1.02) and social costs (ß = 0.03; P = 0.006, exp^ß = 1.03) and duration before fitness-to-work (ß = 0.04; P < 0.001, exp^ß = 1.04). Conclusion: Biopsychosocial complexity assessed with the self-assessment INTERMED questionnaire is associated with higher healthcare and social costs.