The influence of psychiatric disorders on the course of lung cancer, chronic obstructive pulmonary disease and tuberculosis

Background: This Danish study evaluated the association between psychiatric comorbidity and the course of chronic obstructive pulmonary disease (COPD), lung cancer and tuberculosis (TB) of an entire nation. Methods: Data from the Danish National Patient Registry (1998-2009), material status, gender, educational level, comorbidities, age at diagnosis and death, medication, and causes of death were extracted from national databases. We identified 71,874 patients with COPD and found 32,282 with a pre-index psychiatric comorbidity, 20,787 patients with lung cancer and found 8406 with a pre-index psychiatric comorbidity, and 3495 patients with TB and found 797 with a pre-index psychiatric morbidity. Within the three groups we compared the patients with/without a pre-index psychiatric comorbidity. Results: We found a reduced survival in patients with COPD or TB and a pre-existing psychiatric comorbidity. For all three pulmonary diseases, we found significantly higher age (p < .001) at time of diagnosis, higher Deyo-Charlson Comorbidity Index (p < .001), and an overrepresentation of singles (p < .001) in patients with a psychiatric comorbidity. COPD and lung cancer patients with a psychiatric comorbidity were significantly overrepresented by women (p < .001). Patients with COPD and a psychiatric comorbidity died most frequently of lung cancer (24%). Advancing age and Deyo-Charlson index were associated with a higher mortality rate whereas being a woman and married/co-habiting yielded a lower mortality rate for patients with a psychiatric comorbidity. Conclusion: To our knowledge, this is the first epidemiological study investigating the influence of a psychiatric comorbidity on the course of COPD, lung cancer and TB at a national level. Our results emphasize the importance of detecting these major respiratory diseases in patients with psychiatric comorbidities and intensifying the treatment and follow up of these patients.