This study used the path-analyses method to examine the relationship between CRF, FVC, 6MWD, Borg scale, and health-related QoL in patients with lung resection. Our results showed that FVC was poor correlated with QoL. And Bog scales were a strong correlation with physical activities only. Though 6MWD and FVC were positively associated with QoL, an insignificant direct effect between QoL with FVC or 6MWD was observed. Our findings also showed that CRT was a strong correlation with QoL, and took charge of 38.4% of the changes in the perceived quality of life in the model. CRF as a mediator between Pulmonary function, physical activities, Borg scale, and QOL is novel.
Many pieces of evidence showed that lung resection had a significant impact on respiratory function, and the deficits may reduce the patients’ QoL [3, 5]. However, Brunelliet al. found that QoL had a poor correlation with FEV1 and CO lung diffusion capacity . In the present study, we also showed that FVC was not related to QoL. Noting that FVC was positively associated with the general health, vitality, and role-emotional scales of the SF-36, those results indicated that FVC only affected a few functioning scales and could not be taken as surrogates for QOL evaluation . Because the indirect effects from FVC to QoLwere observed in our study, pulmonary function-enhancing intervention may be useful in improving quality of life in patients with resected lung cancer.
Wolkoveet al. reported that dyspnea is poorly correlated with pulmonary function in patients with obstructive lung disease . In the present study, we found that Borg scales were positively associated with physical activities from our mediation model. Furthermore, the main negative relationship between Borg scales and the domains of the SF-36 was physical functioning and role-physical in this study. And the worsening dyspnea caused patients to reduce their physical activities . Those results indicated that Borg dyspnea scaleswere preferred to describe the physical status.
Lung cancer survivors always experience QoL impairments, and engagement in physical activity is associated with better QoL. Also, physical activity was independently associated with QoL in lung cancer patients withpost-curative-intent treatment . We also found that 6MWD was associated with QoL but the significance level was P = 0.044. However, 6MWD recovery in elderly patients after lung cancer surgery was not related to their health-related QOL recoveries . One of the possible reasons for the inconsistent results is that the effect of physical activity on QoL is indirect. Our results confirmed the possibility and an indirect effect between QoL with physical activities were observed.
Cardiorespiratory fitness is determined mainly by aerobic physical activity, and CRF is strong associated with the physical dimensions of health-related QoL . In our study, CRF (VT and VO2max) was positively associated with the physical dimensions except for the pain of QoL, and CRF had a direct effect on QoL. In fact, muchevidence showed that there was a strong correlation between 6MWT , pulmonary function , and CRF. Our results clearly showed that the relationship between physical activity, pulmonary function, and QoL was significantly mediated by CRF in patients with lung cancer resection. This result was similar to the previous works that CRF mediated the effects of 12-week aerobic exercise on general fatigue in a woman with systemic lupus erythematosus . As a mediator, CRF also affected the effects of a Mediterranean diet on the mental component summary of QoL. In our study, CRF (VT and VO2max) was positively associated with 3 out of 4 mental domains of QoL.
In the clinic, QoL in patients with resected lung cancer was poor. Poor QoL means difficulty for these kinds of patients to deal with a range of deficits or limitations related to cognitive, psychosocial, physical, sensory functioning, and other aspects of performance . The results in the present study showed that only 38.5% of the changes in QoLwere due to CRF. Thus, the improving QoL program for the patients with lung resection not only focuses on how to improve CRT, but also pays more attention to other impact factors.
With regard to the limitations of this study, the small number of patients (n = 38) means that the study lacked statistical strength. Second, some other factors that could affect QoL in patients with resected lung cancer were not included in our structural equation modelings such as family supportand economic level. Third, this was a single-center study.
In conclusion, CRF has a direct effect on the quality of life in patients with resected lung cancer. Furthermore, CRT, as mediated variably, can mediate the relationship between pulmonary function, physical activity, Borg dyspnea, and quality of life. In the future, more attention to improving CRT is needed for improving the quality of life of patients with resected lung cancer.