The complexity of outcome measure selection within multiple long-term condition research: an analysis of exercise-based rehabilitation trials

Background
Consistent evidence has demonstrated the health benefits of exercise-based rehabilitation across various long-term conditions (LTC); however, evidence in people with multiple LTC (MLTC; or ‘multimorbidity’) is unclear. Development and evaluation of these interventions for MLTC requires a consensus on relevant outcome measures. We aimed to map the outcomes collected and reported in trials of exercise-based rehabilitation in people with MLTC to an existing core outcome set for MLTC (COSmm), and compare to outcomes reported in exercise-based rehabilitation trials of single LTC.

Methods
A secondary analysis of two systematic reviews assessing exercise-based rehabilitation in MLTC. Outcome measures within included trials were categorised into domains and mapped to the existing COSmm. Domains and measures were also extracted from an overview of systematic reviews investigating exercise-based rehabilitation across single LTC.

Results
Two hundred seventeen outcome measures across 59 trials of exercise-based rehabilitation for MLTC were identified. The most common domains were exercise capacity (26 outcomes across 41 trials (69.5%)) and health-related quality of life (18 outcomes across 35 trials (59.3%)). Mapping to COSmm showed consistency in the collection and reporting of outcomes in the domains of physical function, health-related quality of life, mental health, and intervention adherence. However, no outcome measures could be mapped to domains of communication, shared decision-making, prioritisation, or quality healthcare. Analysis of the overview of systematic reviews across single LTC found heterogeneity in outcome measures with common measures being relatively similar to those reported in MLTC populations.

Conclusion
Current outcomes collected and reported in published trials of exercise-based rehabilitation for MLTC appear to only partially map to the domains of the COSmm. This review highlights the need to consider the specific core outcome set domains needed for collection in future trials of intervention for MLTC including exercise-based rehabilitation.

Contributors

James R. Manifield, Rachael A. Evans, Susan M. Smith, Anne E. Holland, Søren T. Skou, Rod S. Taylor & Sally J. Singh

Publication

Journal: Trials
Volume: 27
Issue: 46
Pages: -
Year: 2026
DOI: https://doi.org/10.1186/s13063-025-09363-y

Further Study Information

Current Stage: Completed
Date:
Funding source(s): This work was supported by a National Institute for Health Research Programme Grant for Applied Research (NIHR202020).


Health Area

Disease Category: Other

Disease Name: Multimorbidity

Target Population

Age Range: 18 - 100

Sex: Either

Nature of Intervention: Exercise

Stakeholders Involved

Study Type

- COS uptake study

Method(s)

- Other

Given the availability of two recently published systematic reviews investigating the effects of exercise-based rehabilitation for people with MLTC [9, 10], outcome measures were extracted from included studies across both reviews. Outcome measures were mapped against the previously developed COSmm.

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