The edemiological state of blunt diaphragmatic injury: An analysis of a nationwide trauma registry in Japan.

Background: Little is known about blunt traumatic diaphragmatic injury (BTDI). This study aimed to investigate the epidemiological state of BTDI, using a nationwide trauma registry in Japan.

Methods: Data of patients aged ≥18 years who experienced blunt injury between January 2004 and May 2019 were extracted from the Japan Trauma Data Bank. Demographics, cause of trauma, mechanism of injury, physiological parameters, organ injuries, and bone fractures were compared between patients with and those without BTDI. Multivariable logistic regression analysis was performed to identify factors associated with BTDI.

Results: A total of 305,141 patients from 244 hospitals were analyzed. The median patient age (interquartile range) was 65 (44-79) years, and 185,750 (60.9%) were men. BTDI was diagnosed in 868 patients (0.3%). The prevalence of BTDI was stable, between 0.2 and 0.6%, over the study period. Among the 868 patients with BTDI, 408 (47.0%) fatalities were recorded. Mortality rates in each year were 42.5-68.2%, with no significant trend toward an improved outcome (P = 0.925). Our multivariable logistic regression analysis found that mechanism of injury, Glasgow Coma Scale score (9-12 or 3-8) on hospital arrival, hypotension (systolic blood pressure <90 mmHg) on hospital arrival, organ injuries (lung, heart, spleen, bladder, kidney, pancreas, stomach, and liver), and bone fractures (rib, pelvis, lumbar spine, and upper extremities) were independently associated with BTDI.

Conclusion: Using a nationwide trauma registry, this study revealed the epidemiological state of BTDI in Japan. BTDI was found to be a very rare but devastating injury, with high in-hospital mortality. Some clinical factors, such as mechanism of injury, Glasgow Coma Scale score, organ injuries, and bone fractures, were independently associated with BTDI.