OBJECTIVES: Patient-reported outcomes (PROs), such as health-related quality of life (HRQoL), are currently considered as important tools for assessment of healthcare quality and effectiveness. However, although a representative sample is essential, it is rarely possible to convince all patients to respond to HRQoL surveys and, therefore, possible over- or underrepresentation of some patient groups can lead to biased estimates. Our aim was to find out how well the patient views obtained by routine collection of PROs in a cardiology unit represent the actual case mix.

METHODS: The representativeness of the responses obtained to routine HRQoL data collection was studied in the Kuopio University Hospital Center which has since 2012, as part of the routine admission process of elective patients, collected HRQoL data using the 15D questionnaire. Elective coronary artery bypass grafting and percutaneous coronary intervention patients treated between June 2012 and August 2014 were included and the characteristics of the patients with a baseline (n=260 and 290 for CABG and PCI, respectively), or both baseline and follow-up HRQoL measurements (n=203 and 189 for CABG and PCI, respectively) were compared with those who did not respond (n=144 and 448 for CABG and PCI). Furthermore, the associations between patient characteristics and the likelihood of obtaining HRQoL data were investigated with logistic regression

RESULTS: Baseline questionnaires were less likely obtained from older CABG patients (OR, 95% CI 0.25, 0.28-0.91) and those with more severe disease (0.20, 0.05-0.79). Among PCI patients, women (0.69, 0.46-1.02), smokers (0.70, 0.49-1.02), and those with more severe disease (0.21, 0.08-0.52) or more hospital days were underrepresented.

CONCLUSIONS: Routinely collected PROs in cardiac patients appeared to be biased towards younger and healthier patients. This needs to be recognized when evaluating the representativeness of such data and every effort should be made to guarantee a response rate as high as possible.