Retrospective evaluation versus population norms for the measurement of baseline health status

Patient recall or the application of population norms are commonly used methods to estimate (unobservable) health status prior to acute-onset illness or injury; however, both measures are potentially subject to bias. This article reports tests of the validity of both approaches, and discusses the implications for reporting changes in health-related quality of life following acute-onset illness or injury.

Recalled pre-injury health status and health status at 5- and 12-months post-injury were collected from participants in a prospective cohort study of people injured in New Zealand. Reported post-injury health status was compared with recalled pre-injury status and New Zealand norms for two groups: those who reported having fully recovered, and those who had not.

There was a small but statistically significant difference between pre- and post-injury health state valuations for people who had fully recovered, with recalled pre-injury health status being higher than reported post-injury health. Perceived health status for those who had fully recovered was significantly higher than the population norm.

Retrospective evaluation of health status is more appropriate than the application of population norms to estimate health status prior to acute-onset injury or illness, although there may be a small upward bias in such measurements.