Prospective external convergence evaluation of two different quality-of-life instruments in lung resection patients

Abstract

The interpretation of studies on quality of life (QoL) after lung surgery is often difficult owing to the use of multiple instruments with inconsistent scales and metrics. Although a more standardized approach would be desirable, the most appropriate instrument to be used in this setting is still largely undefined. The aim of the study was to assess the respective ability of two validated QoL instruments (European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30/L13 and Short Form (36) Health Survey (SF-36)) to detect perioperative changes in QoL of patients submitted to pulmonary resection for non-small-cell lung cancer (NSCLC). A prospective study on 33 consecutive patients (May 2009-December 2009) was submitted to pulmonary resection. All patients completed both EORTC QLQ-C30 with lung module 13 and SF-36 pre- and postoperatively (3 months). Preoperative changes of all SF-36 and EORTC scales were assessed by using the Cohen's effect-size method. External convergence between different instruments (SF-36 vs EORTC) was assessed by measuring the correlation of scales evaluating the same concepts (physical, psychosocial, and emotional). The correlation coefficients between standardized perioperative changes (effect sizes) of objective functional parameters (forced expiratory volume in 1s (FEV1) and diffusion lung capacity for carbon monoxide (DLCO)) and SF-36 or EORTC scales were also investigated. A poor correlation (r < 0.5) was detected between most of the scales of the two instruments measuring the same QoL concepts, indicating that they may be complementary in investigating different aspects of QoL. Only the SF-36 and EORTC social functioning scales and the SF-36 mental health and EORTC emotional functioning scales had a correlation coefficient >0.5. In general, EORTC was more sensitive in detecting physical or emotional declines but was more conservative in detecting improvements. Both SF-36 and EORTC showed poor correlations (r < 0.5) between perioperative changes in QoL and FEV1 or DLCO, confirming that objective parameters cannot be surrogates to the subjective perception of QoL. In particular, there was a poor correlation between perceived changes in dyspnea and objective changes in FEV1 or DLCO. EORTC behaved similarly to SF-36 in assessing perioperative changes in generic QoL scales, but, with the use of its lung module, provided a more detailed evaluation of specific symptoms. For this reason, EORTC should be regarded as the instrument of choice for measuring QoL in the thoracic surgery setting.