Testing and validation of a Patient-Reported Outcome Measure for Older People with frailty and Acute Care needs (PROM-OPAC).

Semi-structured interviews with 15-30 older people living with frailty with recent experience of UK emergency and acute care.* Qualitative analysis using blended approach of framework and comparative methods.

• Outcome: a framework to define outcome goals for acute healthcare among older people living with frailty.

Scoping review to identify existing patient-reported outcome measure instruments with relevance and potential validity to older people with frailty in the acute care setting.

Development of a novel patient-reported outcome measure for this setting.* Review of existing instruments and extensive comparison and reflection with the framework of health outcome goals which has been produced, in order to prepare and exhaustive list of item stems, questions, and responses.

• Reduction, iterative refinement, and evaluation of content validity of the exhaustive list through patient review in interviews, lay collaborator review in surveys, and clinician review in surveys and short interviews, in order to prepare a draft PROM instrument.

Field-testing the draft instrument in UK sites with a representative sample of 150 older people living with frailty.* Evaluation will include feasibility in the form of response rates and feedback, internal consistency, and retest reproducibility, and patient feedback to inform iterative development.

• Outcomes will be reviewed with lay collaborators and clinicians.

Disseminated testing and validation in separate sites with a further sample of 150 older people living with frailty.* Evaluation will include interpretability and construct validity through comparison with alternative measures of healthcare quality.

Evaluation of early implementation and potential applications for PROM-OPAC using follow-up interviews with a small sample of Stage 1 & 2 participants.