Brazilian version of the QLQ-LC13 lung cancer module of the European Organization for Research and Treatment of Cancer: preliminary reliability and validity report.

This study reports the reliability and validity of the Brazilian Portuguese version of QLQ-LC13. After translation and cross-cultural adaptation, the questionnaire was administered, together with the QLQ-C30 core questionnaire, to 82 patients with lung cancer. The analysis was based on 60 patients who completed two interviews, and who received chemotherapy alone or in combination with radiotherapy. The reliability or internal consistency of dyspnea scale was 0.79. The pain scale needed to be combined with the QLQ-C30 pain items to reach a satisfactory value of 0.73. The construct validity was supported by the ability of the questionnaire to discriminate patients regarding their performance status and type of treatment. However, the change over time, although in the expected direction for all items, was statistically significant in four of the 10 items studied. The criterion-related validity was supported by the statistically significant correlation between all four side effect items and the physicians' reports of toxicity, while the evolutive changes in the performance status were statistically significant in only four items. Most psychometric properties of the Brazilian version of the QLQ-LC13 were adequately supported in this analysis. However, a wider utilization of this module is necessary to fully ascertain its reliability and validity properties.