Reliability of the next of kins' estimates of critically ill patients' quality of life.
The aim of this study was to determine the reliability and validity of relatives' assessment of patients' quality of life and to measure the agreement between patients' and relatives' responses to the Short Form 36 quality of life questionnaire, at discharge from and 6 months following intensive care treatment. Ninety-nine patient-relative pairs were studied. Reliability was quantified by using measures of internal consistency (Cronbach's alpha and correlation coefficients) and reliability coefficients. Relatives' responses met the required standards of reliability and validity, but reliability was consistently weaker in the mental health dimension. Relatives' and patients' scores differed significantly in six dimensions at discharge; however, agreement between patients' and relatives' responses, as measured by the Kappa statistic, was fair, improved over 6 months, and was greatest in aspects concerning physical health. We conclude that relatives are able to give a good proxy assessment of functional aspects of quality of life.