Trauma-registry survival outcome follow up: 30 days is mandatory and appears sufficient

Thirty-day in-hospital mortality is a common outcome measure in trauma-registry research and benchmarking. However, this does not include deaths after hospital discharge before 30 days or late deaths beyond 30 days since the injury. To evaluate the reliability of this outcome measure, we assessed the timing and causes of death during the first year after major blunt trauma in patients treated at a single tertiary trauma center.

We used the Helsinki Trauma Registry to identify severely injured (NISS ≥ 16) blunt trauma patients during 2006 to 2015. The Population Register center of Finland provided the mortality data for patients and Statistics Finland provided the cause of death information from death certificates. Disease, work-related disease, medical treatment, and unknown cause of death were considered as non-trauma related deaths. We divided the 1-year study period into the following three categories: in-hospital death before 30 days (Group 1), death after discharge but within 30 days (Group 2), and death 31 to 365 days since admission (Group 3).

We included 3557 patients with a median NISS of 29. Altogether, 21.8% (776/3557) patients died during the first year since the injury. Of these non-survivors, 12.7% (450) were in Group 1, 4.0% (141) in Group 2, and 5.2% (185) in Group 3. Non-traumatic deaths not directly related to the injury increased substantially as the time from the injury increased and were 2.0% (9/450) in Group 1, 13.5% (19/141) in Group 2, and 35.7% (66/185) in Group 3.

Thirty-day mortality is a proper outcome that measures survival after severe blunt trauma. However, applying only in-hospital mortality instead of actual 30-day mortality may exclude non-survivors who die at another facility before day 30. This could result in over-optimistic benchmarking results. On the other hand, extending the follow-up period beyond 30 days increases the rate of non-traumatic deaths. By combining data from different registries, it is possible to address this challenge in current trauma-registry research caused by lack of follow up.