Quality of life assessment in individuals with lung cancer: testing the Lung Cancer Symptom Scale (LCSS).
This paper presents the continued development and multi-institutional testing of an instrument focusing on measuring the physical and functional dimensions of quality of life. It emphasises evaluation of symptoms associated with lung cancer and their effect on activity status. The Lung Cancer Symptom Scale (LCSS) is a disease- and site-specific instrument which has both a patient and an observer (health care professional) form. The patient scale required 8 min to administer and the observer scale 2 min. The readability index was second-grade level for the patient scale and ninth-grade level for the observer scale. Content validity revealed a mean of 96% agreement for all major symptoms among 52 experts surveyed (confidence interval = 86-99%, P = 0.05). 69 patients with non-small cell and 52 patients with small cell lung cancer confirmed that the symptoms matched their experiences. Interrater reliability showed consistency for all items but one among 21 raters at eight institutions; that one item was consistent for 20 of the 21 raters. Similar results were found on a 9-month interval replication. Using the Kappa statistic to estimate extent of agreement for repeated interrater reliability, almost perfect agreement was obtained (mean coefficients, 0.95-0.98). Using the same rule of agreement as for Kappa (+/- one category) intrarater agreement was 95-100% for all 21 raters. Past test re-test reliability indicated high patient reproducibility for 52 patients (r > 0.75, P < 0.01 for all items). We conclude that (1) the LCSS demonstrates good feasibility, reliability, and content validity, (2) high interrater reliability indicates utility in multicentre trials, and (3) continued testing for internal consistency, construct validity and criterion-related validity is warranted.