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Background/Aims: The newly adapted generic KINDL-A(dult)B(rief) questionnaire showed satisfactory cross-sectional psychometric properties in adults with bleeding disorders or thrombophilia. This investigation aimed to evaluate its cross-sectional and longitudinal construct validity. Methods: After ethical committee approval and written informed consent, 335 patients (mean age 51.8 ± 16.6 years, 60% women) with either predominant thrombophilia (n = 260) or predominant bleeding disorders (n = 75) participated. At baseline, patients answered the KINDL-AB, the MOS 36-item Short-Form Health Survey (SF-36), and the EQ-5D-3L. A subgroup of 117 patients repeated the questionnaire after a median follow-up of 2.6 years (range: 0.4–3.5). A priori hypotheses were evaluated regarding convergent correlations between KINDL-AB overall well-being and specific subscales, EQ-5D-3L index values (EQ-IV), EQ-5D visual analog scale (EQ-VAS), and SF-36 subscales. Results: Contrary to hypothesis, baseline correlations between the KINDL-AB and EQ-IV/EQ-VAS were all moderate while, as hypothesized, several KINDL-AB subscales and SF-36 subscales correlated strongly. At follow-up, no significant changes in all three instruments occurred. Correlations between instruments over the follow-up were mostly moderate and partially strong. Contrary to hypothesis but consistent with no significant changes in health-related quality of life, convergent correlations between changes in KINDL-AB overall well-being, physical and psychological well-being, and EQ-IV/EQ-VAS were all weak. Conclusions: While repeated measures of KINDL-AB showed moderate to strong correlations, changes in KINDL-AB overall well-being and subscales correlated more weakly than expected with changes involving two established instruments of generic health status.

Background/Aims: The generic quality of life KINDL-R ­questionnaire is validated for use in children/adolescents ≤16 years. The aim of this cross-sectional investigation was to modify the KINDL-R questionnaire for use in adults and to validate its psychometric properties. Methods: Five items of the KINDL-R questionnaire were adapted and the newly developed KINDL-A(dult) questionnaire administered to 255 patients with hereditary and acquired bleeding disorders (mean age 53 years). Its internal consistency and convergent and divergent construct validity were investigated and confirmatory factor analysis was used to evaluate the latent factor structure. Results: The KINDL-A questionnaire showed satisfactory reliability, varying construct validity, but inconclusive factor structure. The KINDL-AB(rief) was developed by removing half of the items and combining 2 sub-axes. This led to factor loadings between 0.62 and 0.91 and increased overall fit (Goodness of fit > 0.8 and Root Mean Square Error of Approximation, RMSEA, < 0.08). Results were validated in 966 healthy blood donors (mean age 38 years). In this group, the KINDL-AB questionnaire showed factor loadings between 0.43 and 0.77, Goodness of fit > 0.95 and RMSEA < 0.05. Conclusions: The new KINDL-AB suggests sufficient to good psychometric properties in adult patients with hereditary and acquired bleeding disorders.