Referral to chronic pain management and physiotherapy services in adults with severe mental illness: A matched cohort study

Abstract

Introduction

Chronic pain (CP) is common among people with severe mental illness (SMI). It remains unclear whether patients with comorbid CP and SMI receive equivalent pain management referrals compared to those with CP alone. This retrospective cohort study used linked primary and mental healthcare data to address this knowledge gap.

Methods

We identified patients aged ≥18 years with comorbid SMI and CP from secondary mental healthcare records, with the later of either diagnosis serving as the index date. Cases were matched 1:4 by age bands and gender to controls with CP but no SMI diagnosis. Co-primary outcomes were referrals to specialized pain treatment services and musculoskeletal physiotherapy. Cox regression models analyzed associations between SMI status and referral patterns, with sensitivity analyses stratifying follow-up into early (0–3.99 years), medium (4–7.99 years), and late (≥8 years) periods.

Results

The final sample included 1120 patients with CP and SMI and 2681 matched non-SMI controls. SMI diagnosis strongly predicted increased healthcare utilization in adjusted analyses, with significantly higher referral rates to pain treatments (HR = 13.2, 95 % CI 7.8–22.4, p < 0.001) and physiotherapy (HR = 11.5, 95 % CI 9.3–14.4, p < 0.001). The association between SMI and pain treatment referrals was strongest during the early post-diagnosis period (HR = 13.2, 95 % CI 6.6–26.4, p < 0.001).

Conclusion

Contrary to expectations, people with SMI and CP received more pain management referrals compared to matched controls, particularly in the early post-diagnosis period. These findings were restricted to those with a CP diagnosis already, and further research should investigate whether increased referrals translate to improved clinical outcomes.