CHANGE IN FUNCTIONAL CAPACITY AND SELF-PERCEIVED HEALTH STATUS IN PATIENTS WITH CHRONIC MUSCULOSKELETAL PAIN AFTER REHABILITATION. A REGISTRY-BASED LONGITUDINAL STUDY

F. Schütz^1,2, E. Haffter^1,3, A. Meichtry¹, B.R. Winteler^2,4, B.E. Gantschnig^5,1

¹ZHAW Zürich University of Applied Sciences, School of Health Professions, Institute of Physiotherapy, Winterthur, Switzerland, ²Bern University Hospital, Inselspital, Department of Physiotherapy, Insel Gruppe, Bern, Switzerland, ³Medbase AG, Winterthur, Zürich, Switzerland, ⁴Bern University of Applied Sciences, School of Health Professions, Physiotherapy, Bern, Switzerland, ⁵University Hospital (Inselspital) and University of Bern, Department of Rheumatology and Immunology, Bern, Switzerland

Background: Chronic musculoskeletal pain is a major public health problem worldwide. It is not just a nociception of prolonged duration, but a unique, individual experience consisting of dynamic interactions between physiological, psychological and social factors. Patients with chronic musculoskeletal pain report a reduction in both functional capacity and self-perceived health status. In previous studies, functional capacity was mostly assessed using self-reported questionnaires rather than objective measurements. However, self-reported outcome measures carry the risk of recall bias or biased estimation.

Purpose: The aim of this study was therefore to assess the extent of change over time and its clinical meaningfulness in terms of objectively measured functional capacity and self-perceived health status in patients with chronic musculoskeletal pain who participated in an outpatient interprofessional rehabilitation programme.

Methods: The registry-based longitudinal cohort study with prospectively collected data from a rehabilitation programme took place in a real-life setting. Patients (n = 81) with chronic musculoskeletal pain participated in the "BAI-Reha", an interprofessionally organised intervention lasting 12 weeks and consisting of individual and group interventions and independent, self-directed exercise. The main outcomes were the six-minute walk test (6MWT), the safe maximum floor-to-waist lift (SML) and the European Quality of Life and Health measure visual analogue scale (EQ VAS). Timepoints of measurement were at baseline and at 4-month follow-up. The quantity of interest was the adjusted time-effect (point estimate and 95% confidence interval [CI] as well as p-value for the test of the null hypothesis of no change). Statistical significance (= .05) and clinical meaningfulness of the mean value change over time were assessed using predefined thresholds (6MWT 50 m, SML 7 kg, and EQ VAS 10 points).

Results: Linear mixed model analysis showed statistically significant change over time for 6MWT (mean value change 56.08 m, 95% CI [36.13, 76.03]; p<.001), SML (mean value change 3.92 kg, 95% CI [2.66, 5.19]; p<.001) and EQ VAS (mean value change 9.58 points, 95% CI [4.87, 14.28]; p<.001). Moreover, the improvement in the 6MWT is clinically meaningful (mean value change 56.08 m) and in the EQ VAS is almost clinically meaningful (mean value change 9.58 points).

Conclusions: Patients walk further, lift more weight and feel healthier at 4-month follow-up after outpatient interprofessional rehabilitation when compared to baseline measurement. The improvement in walking and lifting was demonstrated by functional testing, which is potentially more objective or less prone to bias than self-reported estimates of functional capacity. These findings confirm and complement those of previous studies.

Implications: We encourage other providers of rehabilitation for patients with chronic musculoskeletal pain to measure functional capacity with objective outcome variables and to use self-reported outcome measures in addition to self-perceived health status. The well-established assessments used in this study are suitable for this purpose.

Funding acknowledgements: Our Chronic Pain registry is mainly funded internally and supported by the Foundation Johanna Dürmüller-Bol and Sandoz Pharmaceuticals AG.

Keywords:
Functional Status
Patient Outcome Assessment
Multidisciplinary Pain Clinic

Topics:
Musculoskeletal
Pain & pain management
Disability & rehabilitation

Did this work require ethics approval? Yes

Institution: Bern University Hospital, Switzerland

Committee: Ethics Review Board Bern, Switzerland

Ethics number: 2018-01583