The validity of proxy responses on patient-reported outcome measures: Are proxies a reliable alternative to stroke patients’ self-report?

Caregivers, or proxies, often complete patient-reported outcome measures (PROMs) on behalf of patients with stroke. The objective of our study was to assess the validity and responsiveness of proxy-responses compared to patient-responses across multiple domains of health.

Stroke patients and their proxies were recruited to complete PROMs between 7/2018–11/2019. PROMs included Neuro-QoL cognitive function, PROMIS physical function, satisfaction with social roles, anxiety, fatigue, pain interference, sleep disturbance, Global Health, and PHQ-9. Internal consistency and convergent validity were compared between patient- and proxy-reported measures. Known-groups validity was assessed across levels of stroke disability. Internal responsiveness was evaluated using paired t-tests for a subset of patients who attended rehabilitation following stroke. Analyses were stratified by patients ≤ 3 vs > 3 months from stroke.

This cross-sectional study included 200 stroke patients (age 62.2 ± 13.3, 41.5% female) and their proxies (age 56.5 ± 13.9, 70% female, 72% spouses). PROMs had high internal consistency and were significantly correlated for patients and proxies. Patient- and proxy-reported measures worsened with increasing stroke disability. For 34 (17%) patients who attended rehabilitation, patients self-reported improvement on 5 domains whereas proxies reported no improvement. Compared to patient self-reports, validity was worse for proxy-reports on patients ≤ 3 months but better > 3 months from stroke.

Both patient- and proxy-reported PROMs demonstrated strong validity. Only patient-reported PROMs were responsive to change, and proxies had worse validity for patients ≤ 3 months from stroke but better validity for patients > 3 months from stroke. These findings justify the utilization of proxy responses in stroke patients > 3 months from stroke.