Assessing validity and reliability of the Positive Health and Individual Recovery Outcomes Counter questionnaires for measuring self-reported changes in Positive Health

Abstract Positive Health is gaining attention for measurement purposes. In this study, the 17-items Positive Health (PH17) questionnaire and the 12-items Individual Recovery Outcomes Counter (I.ROC12) questionnaire were investigated on usefulness for measuring self-reported changes in Positive Health. An observational study was performed in a Dutch post-covid-19 patient population to assess test-retest reliability (intraclass correlation coefficient (ICC), standard error of measurement (SEM), and smallest detectable change (SDC)), internal consistency and construct validity by hypothesis testing. PH17, I.ROC12 and – for comparison – EQ5D-VAS were completed at six (T6) and twelve (T12) months after hospital discharge and again within 5 days after T12 (retest). For PH17, test-retest reliability was good for five factors and the total score (ICC >0.7, SEM 0.9 and too low for the factor Future perspective (0.9, SEM