Measuring the quality of life of cancer patients

Abstract

To complement the hard variables generally used in the assessment of different treatments for cancer and other chronic diseases we developed a ‘hardened’, succinct quantitative index to measure the quality of life (QL-Index) of survivors. It was designed for use by physicians. It has five items and its range of scores is 0–10. It was used in pretests and validation tests by more than 150 physicians to rate 879 patients; median completion time was one minute. Fifty-nine percent of physicians reported that they were at least ‘very confident’ of the accuracy of their scores. We established predetermined criteria for validity before field work commenced and evaluated the index using convergent and discriminant approaches of construct validity, as well as content validity. The QL-Index has convergent discriminant and content validity among cancer patients and patients with other chronic physical diseases. Assessment of internal consistency demonstrated a high coefficient (Cronbach's α = 0.775) and the interrater Spearman rank correlation was high and statistically significant (rho = 0.81, P < 0.001) when independent scores of two physicians were compared, or doctors ratings were compared to self-ratings of patients (rho = 0.61, P < 0.001) Our aim has been to provide a new measure that can help physicians assess the relative benefits and risks of various treatments for serious illness and of supportive programs such as palliative care or hospice service. The QL-Index is not, however, suitable for measuring or classifying the quality of life of ostensibly healthy people.