Table 1 Criteria of quality of psychometric properties [87]

Content validity

The degree to which the content of an instrument is an adequate reflection of the construct to be measured

(+) A clear description is provided of the measurement aim, the target population, the concepts that are being measured, and the item selection AND target population and experts were involved in item selection

(?) A clear description of above-mentioned aspects is lacking OR only target population involved OR doubtful design or method

(−) No target population involvement

(0) No information found on target population and experts’ involvement

Internal consistency

The degree which items are intercorrelated, thus measuring the same construct

(+) Factor analyses performed on adequate sample size (7 times the number of items)

AND Cronbach’s alpha(s) or McDonald’s omega(s) between 0.70 and 0.95 for each scale

(?) Cronbach’s alphas or McDonald’s omega(s) presented without factor analysis considered OR doubtful design or method

(−) Cronbach’s alpha(s) or McDonald’s omega(s) < 0.70 or > 0.95

(0) No information found on internal consistency

Criterion validity

The degree to which the scores of an instrument are an adequate reflection of a ‘gold standard’

(+) Convincing arguments that gold standard is ‘‘gold’’ AND correlation

with gold standard ≥ 0.70

(?) ≥ 0.70 correlation presented without convincing arguments that gold standard is ‘‘gold’’ OR doubtful design or method

(−) Correlation with gold standard < 0.70

(0) No information found on criterion validity

Construct validity

The degree to which scores on a particular questionnaire relate (or are unrelated) to other measures in a manner that is consistent with theoretically derived hypotheses concerning the concepts that are being measured

(+) Explicitly tested for AND at least 75% of the results are in expected direction and size (e.g., reporting the correlation between two measures in the expected direction, or the expected lack of correlation)

(?) Doubtful design or method (e.g., not explicitly tested)

(−) Less than 75% of results as expected

(0) No information found on construct validity

Reproducibility Agreement (test–retest)

The extent to which the scores on repeated measures are close to each other (absolute measurement error)

(+) Test–retest agreement r > .70 AND means and standard deviations are

presented at both time points

(?) > 0.70 correlation presented without means and standard deviations at both

time points OR doubtful design or method

(−) Test–retest agreement r < .70

(0) No information found on test–retest reliability

Reliability

The extent to which patients can be distinguished from each other, despite measurement errors (relative measurement error)

(+) T tests ICC or weighted Kappa > 0.70

(?) Doubtful design or method (e.g., time interval not mentioned or less valid measure then a Kappa used)

(−) ICC or weighted Kappa < 0.70;

(0) No information found on reliability

Responsiveness

The ability of an instrument to detect clinically important changes over time in the construct to be measured

(+) Treatment program outlined, and longitudinal expected changes presented AND > 75% of results are as expected OR RR > 1.96 OR AUC > 0.70

(?) Doubtful design or method

(−) RR < 1.96 OR AUC < 0.70

(0) No information found on responsiveness

Floor and ceiling effects

The number of respondents who achieved the lowest or highest possible score

(+) < 15% of the respondents achieved the highest or lowest possible scores

(?) Doubtful design or method

(−) > 15% of the respondents achieved the highest or lowest possible scores

(0) No information found on floor and ceiling effects

Interpretability

Degree to which one can assign qualitative meaning to an instrument’s quantitative scores or change in scores

(+) Mean and SD scores presented for at least four relevant subgroups of patients^c

(?) Doubtful design or method (e.g., data provided on less than four subgroups)

(0) No information found on interpretation