Questionnaires Validity Reliability Responsiveness and floor/ceiling effects Minimal important difference
PBC-40
Construct validity Moderate to high correlations with the SF-36 and ESI-55 scales, except for “Physical functioning” domain of the SF-36 and “Itch” domain of the PBC-40[17] Internal consistency Cronbach’s alpha >0.7 for all scales[13] Cronbach’s alpha >0.7 for all scales[14] Cronbach’s alpha >0.7 for all scales[17] Test‐retest ICC ranged 0.83-0.96[17] Floor and ceiling effects There were no ceiling effects but there was a noticeable floor effect in the itch domain (36.7%)[15]
PBC-27
Convergent validity minor correlations between the PBC-27 social factor and the SF-36 social functioning, but moderate to high correlations in majority of scales[12] Internal consistency Cronbach’s alpha >0.7 for all scales[12] Cronbach’s alpha >0.7 for all scales, except for domains “Dryness”, “Symptoms” and “Fatigue” [13]
PBC-10
Content validity Generally good, developed by hepatology experts in PBC[15] Internal consistency Internal consistency was excellent with Cronbach’s alpha of 0.936. Test‐retest ICC=0.945 for all scales[15] Floor and ceiling effects There were no ceiling effects but a floor effect was obvious[15] responsiveness ratio of 0.38, effect size of 0.39 and standardised response mean of 1.25. Responsiveness Small to moderate responsiveness[15] The minimal import‐ ant difference was 3.539[15]
NIDDK-QA
Concurrent validity Small to high correlations with the SF-36 scales, P <0 .01[16] Internal consistency Cronbach’s alpha ranged from 0.87 to 0.94 Test‐retest Pearson coefficients: 0.82-0.99, P <0 .01[16]