Table 3.

Definitions of the Scored Measurement Properties

Measurement property	Definition
General recommendations for study design	The study requires a clear research aim and a clear description of the PROM and the study population. The quality should be determined in the target population in which the PROM will be used
Content validity	Whether the PROM items are relevant, comprehensive, and comprehensible in terms of the construct of interest and study population, by asking patients and professionals. This is a subjective judgment of the reviewers
Structural validity	The degree to which the scores of a PROM are an adequate reflection of the dimensionality of the construct to be measured, usually assesses by factor analysis
Internal consistency	The degree of interrelatedness among the items, assessed by Cronbach alpha
Reliability	The extent to which the measurement yields consistent reproducible estimates of what is assumed to be an underlying true score
Hypothesis testing for construct validity	As no ‘gold standards’ exist for PROMs, the commonly used way to investigate the validity is to test hypothesis about expected relationships with other outcome measurements. The authors used the SF-36