Clinical relevance of single item quality of life indicators in cancer clinical trials

We investigated the hypothesis that global single-item quality-of-life indi cators are less precise for specific treatment effects (discriminant validi ty) than multi-item scales but similarly efficient for overall treatment co mparisons and changes over time (responsiveness) because they reflect the s ummation of the individual meaning and importance of various factors. Linea r analogue self-assessment (LASA) indicators for physical well-being, mood and coping were compared with the Hospital Anxiety and Depression Scale (HA D), the Mood Adjective Check List (MACL) and the emotional behaviour and so cial interaction scales of the Sickness Impact Profile (SIP) in 84 patients with early breast cancer receiving adjuvant therapy. Discriminant validity was investigated by multitrait-multimethod correlation, responsiveness by standardized response mean (SRM). Discriminant validity of the indicators w as present at baseline but less under treatment. Responsiveness was demonst rated by the expected pattern among treatments (P = 0.008). In patients wit hout chemotherapy, the SRMs indicated moderate (0.5-0.8) to large (>0.8) im provements in physical well-being (0.70), coping (0.92), HAD anxiety (0.89) and depression (1.19), and MACL mental well-being (0.68). In patients with chemotherapy for the first 3 months, small but clinically significant impr ovements (>).2) included mood (0.38), coping (0.41), HAD axiety (0.31) and MACL mental well-being (0.35). Patients with 6 months chemotherapy showed n o changes. The indicators also reflected mood disorders (HAD) and marked ps ychosocial dysfunction (SIP) at baseline and under treatment according to p re-defined cut-off levels. Global indicators were confirmed to be efficient for evaluating treatments overall and changes over time. The lower reliabi lity of single as opposed to multi-item scales affects primarily their disc riminant validity. This is less decisive in large sample sizes. (C) 2001 Ca ncer Research Campaign.