Test-retest reliability of HeartQoL and its comparability to the MacNew heart disease health-related quality of life questionnaire

Objectives Heart Quality of Life (HeartQoL) is a new hybrid'' developed from the MacNew and two condition-specific questionnaires measuring health-related quality of life (HRQoL) in patients with ischemic heart disease (IHD). This study investigates test-retest reliability of HeartQoL (English version) according to international criteria (e.g., COSMIN, GRRAS). Findings on HeartQoL are compared to the published data on MacNew in view that both serve as the core IHD-specific HRQoL instrument. Methods Out of 105 patients with IHD, 76 completed self-administration of HeartQoL at the clinic followed by at home within a 2-week interval. In retest, patients responded using non-interview methods (phone messaging, email, fax, and post). Phone interviewing was reserved for non-respondents to reminder. Results Reliability of HeartQoL was good (intraclass correlation coefficients = 0.78-0.82), was supported in the Bland-Altman plot, and was comparable to five studies on MacNew of similar retest interval (MacNew-English = 0.70-0.75; translated MacNew = 0.72-0.91). Applicability of its standard error of measurement (0.20-0.25) and smallest detectable change (0.55-0.70) will depend on availability of normative data in future. Conclusion The reliability of HeartQoL is comparable to its parent instrument, the MacNew. The HeartQoL is a potentially reliable core IHD-specific HRQoL instrument in measuring group change.