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Christiansen D.H.1,2, de Vos Andersen N.-B.2, Poulsen P.H.1, Ostelo R.3,4
1Hospital Unit Regional Hospital West Jutland, Department of Occupational Medicine - University Research Clinic, Herning, Denmark, 2Central Denmark Region, Primary Health Care and Quality Improvement, Viborg, Denmark, 3VU University, Department of Health Sciences, Amsterdam, Netherlands, 4VU University Medical Centre, Department of Epidemiology and Biostatistics, Amsterdam, Netherlands
Background: Results from clinical trials have supported the use of physiotherapy (manual therapy and exercise) for neck, shoulder and low back pain, but methods to determine whether these observed treatment effects are of clinical significance is an ongoing topic of discussion. The smallest worthwhile effect (SWE) of an intervention is the smallest beneficial effect, taking into account the cost, potential side effects and inconveniences of that intervention, large enough to justify the use of the intervention in clinical practice.
Purpose: To determine and compare estimates of the SWE for physiotherapy for neck, shoulder and low back pain and to investigate the possible influence of socio demographic, clinical and physiological factors on these estimates.
Methods: The study was nested in a larger prospective cohort study of patients seeking physiotherapy for neck, shoulder or low back pain in 21 physiotherapy practices across Denmark in the period from January to June 2016. Patients who consented were contacted by telephone and a structured interview was performed before treatment was commenced. The benefit-harm-trade-off method was used to estimate the SWE for additional improvement by physiotherapy treatment in three outcomes; pain, disability and time to recovery for each patient, as compared to improvement that could occur as a result of natural recovery. To explore its possible influence, information on socio demographic, clinical and physiological factors was collected by a web-based questionnaire prior to the first consultation and electronic clinical recording sheets were completed by the treating physiotherapist. The distribution of estimates of the SWE for each outcome was calculated and compared with respect to pain location (neck, shoulder or low back). Possible influence of baseline characteristics and intake scores was examined by regression analyses.
Results: A total of 160 patients were included in the study (age 50.7±14.2, 56% female). The distributions of patients with respect to pain location were: neck 26%, shoulder 33%, and low back 41%. The median SWE for additional improvement on pain and disability was 20% (interquartile range [IQR] 10-30%) and median SWE for time to recovery was 10 days (IQR 7-14) over a period of six weeks. No significant differences in SWE estimates were observed with respect to pain location (neck, shoulder or low back). Adjusting for baseline characteristics and intake scores had no decisive impact on the results.
Conclusion(s): People with neck, shoulder and low back pain needs to see at least 20% additional improvement on pain and disability over natural recovery to consider the effect of physiotherapy to be worth its costs, potential side effects and inconveniences.
Implications: Findings from this study may guide clinicians and policy makers when interpreting findings from clinical trials, setting standards when monitoring clinical guidelines. It may also allow researchers to design trials, in similar health care systems to Denmark, sufficiently powered to detect effects that a typical patient seeking physiotherapy would consider large enough to be worthwhile.
Funding acknowledgements: The study was supported by the Practice Research Foundation of Central Denmark Region and the Danish Arthritis Foundation.
Topic: Musculoskeletal: spine
Ethics approval: As treatment was not affected by participation in the study, under Danish law, this study did not need ethics approval
All authors, affiliations and abstracts have been published as submitted.
