Subtype consideration in hip fracture research: patient variances in inter- and intra-classification levels highlight the need for future research deliberation. A 2-years follow-up prospective-historical cohort

Current research on elderly patients with hip fractures often neglects specific subtypes, either grouping all fracture types or overlooking them entirely. By categorizing elderly patients based on fracture subtypes, we observed diverse baseline characteristics but found no discrepancies in measured outcomes. This emphasizes the need for caution in future research dealing with different or broader measured outcomes that were not covered by the scope of this research.

Purpose/introduction: Existing research in elderly patients with hip fractures often overlooks the distinct subtypes or lumps all fracture types together. We aim to examine the differences between hip fracture subtypes to assess if these differences are meaningful for clinical outcomes and should be considered in future research.

Methods: Patients above 65 years who underwent hip fracture surgeries during a three-year period were retrospectively reviewed. Cases were grouped based on fracture subtype: non-displaced femoral neck (nDFN), displaced femoral neck (DFN), stable intertrochanteric (sIT), and unstable intertrochanteric (uIT).

Results: Among the 1,285 included cases, the nDFN-group had lower ASA scores (p = 0.009) and younger patients (p < 0.001), followed by the DFN-group (p = 0.014). The uIT-group had a higher proportion of female patients (72.3%, p = 0.004). Differences in preoperative ambulation status were observed (p = 0.001). However, no significant associations were found between fracture type and postoperative outcomes, including ambulation, transfusions, complications, reoperations, or mortality. Gender and preoperative ambulation status were predictors of mortality across all time frames. ASA score predicted mortality only within the first year after surgery. Age and gender were predictors of postoperative blood transfusions, while age and preoperative ambulation status were predictors of postoperative complications.

Conclusions: Variations in baseline characteristics of hip fractures were observed, but no significant differences were found in measured outcomes. This indicates that the hip fracture group is not homogeneous, emphasizing the need for caution in research involving this population. While grouping all types of proximal femur fractures may be acceptable depending on the outcome being studied, it's essential not to extrapolate these results to outcomes beyond the study's scope. Therefore, we recommend consider hip fracture subtypes when researching different outcomes not covered by this study.