The direct and indirect impact of comorbidity on the survival of patients with non-small cell lung cancer: a combination of survival, staging and resection models with missing measurements in covariates.

Objective: To examine the direct and indirect impact of comorbidity on the survival.
Design: A historical cohort study.
Setting: Denmark.
Participants: All patients with non-small cell lung cancer who were registered in the Danish Lung Cancer Registry in 2010.
Main Outcome Measures: The influence of comorbidity on stage misclassification, probability of resection and survival.
Results: It was estimated that the comorbidity influences the probability of resection with OR 0.65 and 95% credible interval (0.54; 0.79), the staging process with OR 1.08 and 95% credible interval (0.96; 1.20), and the survival process with HR 1.08 and 95% credible interval (1.02; 1.14).
Conclusions: We found that comorbidity has a significant indirect effect on survival mediated by the resection process and a slightly direct effect on mortality.