Disaster‐related carbon monoxide poisoning after the Great East Japan Earthquake, 2011: a nationwide observational study

Abstract

Aim To investigate disaster-related carbon monoxide (CO) poisoning after the Great East Japan Earthquake using a nationwide inpatient database in Japan. Methods This was a retrospective cohort study. We identified adult patients with CO poisoning who were registered in the Japanese Diagnosis Procedure Combination inpatient database from 2010 to 2017. We evaluated trends in the numbers of patients with CO poisoning each month from disaster (Tohoku region) and non-disaster areas. In the disaster area, we compared the numbers of patients with CO poisoning during pre- and post-earthquake periods. We also compared the numbers of CO poisonings after the earthquake (<30 days) and 1 year later. Results Eligible patients (n = 7,814) were categorized into disaster area (n = 988) and non-disaster area (n = 6,826) groups. The numbers of CO-poisoned patients in the non-disaster area showed a seasonal variation, and there was a significant peak registered on March 11 in the disaster area. In the disaster area, the number of patients with CO poisoning in the post-earthquake period was significantly higher than that in the pre-earthquake period (135 versus 18; odds ratio, 7.50; 95\% confidence interval, 4.59-12.3). The number of patients in the post-earthquake period was also significantly higher than that on April 9, 2012, which was one month after the annual follow-up (135 versus 10; odds ratio, 13.5; 95\% confidence interval, 7.10-25.7). Conclusion This study showed that CO poisoning significantly increased in the affected area after the Great East Japan Earthquake, underlining the importance of providing information regarding the hazard of earthquake-related CO poisoning.