This study tests our hypothesis that patients with chronic obstructive pulmonary disease (COPD) have an increased risk of traumatic brain injury (TBI).

In this nationwide retrospective cohort study, we used a subset of Taiwan's National Health Insurance Research Database, involving 1 million randomly selected beneficiaries. Patients with newly diagnosed COPD between 2000 and 2008 were identified. They were subgrouped as ‘COPD_AE+’ (if they had severe acute exacerbation of COPD during the follow-ups) or ‘COPD_AE−’ (if they had no acute exacerbation), and were frequency matched with randomly selected subjects without COPD (the ‘non-COPD’ group). Baseline differences were balanced by the inverse probability of treatment weighting based on the propensity score. For each patient, the risk of TBI during the subsequent 5 years was determined. The competing risk of death was controlled.

We identified 3734 patients in ‘COPD_AE+’, and frequency matched them with 11,202 patients in ‘COPD_AE−’ and 11,202 subjects in ‘non-COPD’. Compared with those in ‘non-COPD’, patients in ‘COPD_AE+’ and ‘COPD_AE−’ had an increased risk of TBI: the adjusted HR for ‘COPD_AE+’ was 1.50, 95% CI 1.31 to 1.73, and that for ‘COPD_AE−’ was 1.21, 95% CI 1.09 to 1.34. The highest risk was observed in the ‘COPD_AE+’ group that aged <65 (the adjusted HR was 1.92; 95% CI 1.39 to 2.64).

COPD has been linked to complications beyond the respiratory system. In this study we showed that COPD is associated with an increased risk of TBI.