B. W. Oliphant1, C. Harris3, A. Cain-Nielsen2, J. Goulet1, M. Hemmila2 1University Of Michigan,Department Of Orthopaedic Surgery,Ann Arbor, MI, USA 2University Of Michigan,Department Of Surgery,Ann Arbor, MI, USA 3University Of Maryland,Department of Surgery,Baltimore, MD, USA
Introduction: The accuracy and completeness of data in registries is essential to making valid conclusions about outcomes. The selection of Not Further Specified (NFS) in injury coding means that the data abstractor could not identify an exact diagnosis. We hypothesize that there is a significant amount of not classified orthopaedic injuries in trauma registries. Our primary outcome was to quantify the amount and type of NFS orthopaedic injuries in trauma registries. Our secondary outcome was to examine factors that could contribute to these findings.
Methods: Data from the Michigan Trauma Quality Improvement Program (MTQIP) from 2011-2017 and from the National Trauma Data Bank (NTDB) from 2011-2015 were utilized. We analyzed orthopaedic injuries in these registries which were classified via the Abbreviated Injury Scale version 2005 (AIS2005). Fractures were identified via AIS2005 as either a specific injury type or as a NFS injury. They were also grouped by fracture complexity into “simple” (i.e. tibial diaphysis, proximal femur, etc.) or “complex” (i.e. pelvic ring, acetabulum, etc.). Average fracture volumes seen at these centers and trauma center level was also extracted. Linear regression was used to evaluate the effect of volume and trauma center level on NFS entries.
Results: In MTQIP, 18.5% of entries (13,116 of 70,918 fractures) were classified as NFS, with a range of 2.4-67.9% based on specific fracture type. In the NTDB, 27% (342,472 of 1,269,278 fractures) were NFS, range of 6.0-68.5%. There were significantly more complex NFS fractures (34.5%) than simple (9.6%) [p<0.001] in MTQIP, with similar findings in the NTDB, (41.8%) complex vs. (15.7%) simple [p<0.001]. In MTQIP, Level 1 trauma centers had a higher percentage of NFS injuries, 21.2% vs. 16.6% [p<0.001] while the opposite was true in NTDB with Level 2 centers having more NFS injuries, 26.6% vs. 24.4% [p<0.001]. Increasing fracture volume and Level 2 status were associated with a decrease in the proportion of NFS fractures recorded in both databases.
Conclusion: This analysis demonstrates that a significant amount of orthopedic injury data found in trauma registries is incomplete and could be considered “missing.” Higher injury volume and less complicated injuries improve the recording of this data. With the increase in orthopaedic research utilizing large databases and registries, the completeness of this data is paramount to being able to make accurate conclusions and subsequently drive appropriate improvements in systems, processes and policy. Further work should delve into the reasons for these findings so that these data sources can be strengthened and become a source of reliable information.