Psychometric validation of the Patient Symptom Assessment in Lung Cancer instrument for small cell lung cancer.

OBJECTIVE: Patient Symptom Assessment in Lung Cancer (PSALC) is a symptom scale developed for use in patients with small cell lung cancer (SCLC) to assess nine lung cancer symptoms (shortness of breath, cough, chest pain, hemoptysis, appetite loss, sleep interference, hoarseness, fatigue, interference with daily activities) scored from 1 (not at all) to 4 (very much). This study aims to retrospectively evaluate the psychometric properties of PSALC using clinical trial data. METHODS: Data were analyzed from a randomized, open-label, multicenter trial with 211 patients with SCLC receiving i.v. topotecan versus cyclophosphamide, doxorubicin, and vincristine. PSALC was evaluated at baseline and at 3-week intervals. Internal consistency, reliability, construct validity, and responsiveness were evaluated. RESULTS: Factor analysis indicated that one factor could represent all symptom items, so a PSALC total score (PSALC-TS) was used for psychometric validation. Internal consistency was supported by Cronbach's alpha of 0.74. Reliability of PSALC was supported by an intraclass correlation coefficient of 0.61 and concordance correlation coefficient of 0.72. Construct validity was supported by associations of lower PSALC-TS (less severe symptoms) with better ECOG performance status (p < 0.0001), and of PSALC-TS changes with clinical response. PSALC-TS was responsive to tumor progression (responsiveness statistic = 0.64). LIMITATIONS: The validation was performed retrospectively and was limited by small sample sizes at later assessment timepoints due to disease progression. CONCLUSIONS: A retrospective analysis suggests that the PSALC is a reliable, valid, and responsive instrument for measuring SCLC symptoms. If feasible in this population, a prospective validation study could be used to further evaluate these findings.