Not Further Specified: Unclassified Orthopedic Injuries in Trauma Registries, Cause for Concern?

Data accuracy is essential to obtaining correct results and making appropriate conclusions in outcomes research. Few have examined the quality of data that is used in studies involving orthopedic surgery. A nonspecific data entry has the potential to affect the results of a study or the ability to appropriately risk adjust for treatments and outcomes. This study evaluated the proportion of Not Further Specified (NFS) orthopedic injury codes found into two large trauma registries.

Data from the National Trauma Data Bank (NTDB) from 2011 to 2015 and from the Michigan Trauma Quality Improvement Program (MTQIP) 2011-2017 were used. We selected multiple orthopedic injuries classified via the Abbreviated Injury Scale, version 2005 (AIS2005) and calculated the percentage of NFS entries for each specific injury.

There were a substantial proportion of fractures classified as NFS in each registry, 18.5% (range 2.4%-67.9%) in MTQIP and 27% (range 6.0%-68.5%) in the NTDB. There were significantly more NFS entries when the fractures were complex versus simple in both MTQIP (34.5% versus 9.6%, P < 0.001) and the NTDB (41.8% versus 15.7%, P < 0.001). The level of trauma center affected the proportion of NFS codes differently between the registries.

The proportion of nonspecific entries in these two large trauma registries is concerning. These data can affect the results and conclusions from research studies as well as impact our ability to truly risk adjust for treatments and outcomes. Further studies should explore the reasons for these findings.