Trials with proxy-reported outcomes registered on the Australian New Zealand Clinical Trials Registry (ANZCTR)

A proxy is someone other than a patient who reports a patient’s outcomes as if they are the patient. Due to known discordance with patient reports, proxies are often not recommended in clinical trials; however, proxies may be needed in certain research contexts. We aimed to identify and describe trials registered on the Australian New Zealand Clinical Trials Registry (ANZCTR) with proxy-reported endpoints.

ANZCTR was systematically searched from inception (2005) to 31 March 2017 for trials with proxy-reported endpoints. Primary and secondary endpoints for each trial retrieved by the search were individually coded (proxy-reported: yes/no), and trials with confirmed proxy-reported endpoints were included in the analysis.

Of 13,666 registered trials, 469 (3.4%) included a proxy-reported endpoint (867 individual proxy-reported endpoints in total: 62% family member proxy, 22% health professional). Proxy endpoint inclusion did not significantly increase over time (r = 0.18, p = 0.59). Mental health (11.5%), stroke (10.3%) and neurological (8.3%) trials had the highest proportion of trials using proxies. Of the 469 trials, 123 (26.2%) studies involved paediatric patients.

Proxy-reported endpoints are included in a small but notable number of studies, which may indicate other types of outcomes are used for patients unable to self-report, or that these patients are under-researched.