Background: Common diseases with potential to increase the risk of death from lung cancer have so far not been studied in large populations. Methods: We did a population-based retrospective cohort study using nationwide health insurance claims data from 2005 to 2012 in Korea including 205 403 lung cancer patients. Multivariate-adjusted hazard ratios (aHRs) of lung cancer mortality by presence, time intervals with lung cancer diagnosis and combinations of pre-existing chronic obstructive pulmonary disease (COPD), pneumonia, asthma and tuberculosis were calculated using the Cox-proportional hazards model. Results: The total number of person-years of follow-up was 397 780 and 60.2% of patients died (mean survival 23.2 months after lung cancer diagnosis). Lung cancer patients with previous respiratory disease had increased aHR for mortality (COPD, hazard ratio [HR] = 1.32, CI 1.29–1.35; pneumonia, HR = 1.14, CI 1.08–1.19; and asthma, HR = 1.11, CI 1.06–1.16). Risks were positively associated with longer duration of pre-existing disease diagnosis; cases with >5 years since diagnosis compared to <2 years: COPD, HR = 2.91, CI 2.82–3.00; pneumonia, HR = 1.67, CI 1.51–1.85; asthma, HR = 1.56, CI 1.45–1.68; and tuberculosis, HR = 2.03, CI 1.90–2.17. Furthermore, elevated HRs of death were found among patients with multiple pre-existing co-morbidities. Conclusion: Hazards of death from lung cancer are significantly increased in cases with pre-existing lung disease, and worse with longer durations, and with multiple combinations before cancer diagnosis. Patients and physicians should be aware of these meaningful risk/prognostic factors for lung cancer when identifying high-risk patient groups.
Bibliographical noteFunding Information:
This work was supported by the Soonchunhyang University Research
S.H. and S.J.K. designed the study, researched data, performed statistical analyses and wrote the manuscript. E.C.P., K.B.Y., J.A.K., K.T.H., T.H.K. and J.W.Y. contributed to the discussion and reviewed and edited the manuscript. S.J.K. is the guarantor of this work, and, as such, had full access to all data in the study and accepts responsibility for the integrity of the data and the accuracy of the data analysis. The manuscript is prepared with the manner of honest, accurate and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned. Approved by Institutional Review Board, Yonsei University Graduate School of Public Health (2014?203). This work was supported by the Soonchunhyang University Research Fund.
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