The study showed that perioperative blood transfusion rates were higher in patients with hip fractures with DM than in those without DM. No notable differences in the length of stay, direct total charges, or 1-year mortality were demonstrated. This suggests that diabetes increases perioperative blood transfusion rates for hip fractures without significant increases in length of hospital stay, direct costs, and early postoperative mortality. The current study has also found that patients in the diabetic group had lower baseline hemoglobin and hematocrit levels at admission than those in the non-diabetic group, while the number of waiting days before surgery and baseline albumin levels at admission were close to those in the non-diabetic group.
In contrast to our study, Wang H et al. [11] found that the combination of diabetes did not significantly increase the perioperative transfusion demand for hip fracture. However, our findings, consistent with the findings of Chanseok R et al. and Bolognesi MP et al. [12, 13], suggesting that co-diabetes increases perioperative blood transfusion requirements for hip fractures. Mehdi U and Thomas MC [14, 15] suggest that the increased demand for blood transfusion in diabetic patients with hip fractures may be explained by evidence that diabetics are more prone to anemia. In any case, there is no clear evidence linking diabetes directly to an increased risk of perioperative blood transfusion for hip fracture, and we are more inclined to think that complications such as diabetic nephropathy and DM-related malnutrition are more likely to cause diabetes-related anemia, leading to an increase in perioperative blood transfusion demand in diabetic patients. This could explain the lower baseline hemoglobin and hematocrit levels found in our study in patients with DM who were admitted to hospital.
Notably, the study found no significant increase in the direct costs and length of hospital stay in patients with diabetes. This was completely contrary to the research results of Wang H et al. [11] and Pope D et al. [16].The direct cost and length of stay in hospital have complicated relationship with income level, occupation type and other factors, and it is difficult to explain by single factor of DM.
In our study, the number of diabetic female patients with hip fracture (85.9%) was significantly greater than that of male patients (14.1%). These results are in line with those of previous studies [11, 17]. However, a systematic review by Janghorbani M et al.[18] found that hip fractures were more likely to occur in men with diabetes. The reason for the discrepancy may be because of different socioeconomic conditions, geographical differences, or different medical systems.
In addition, our results suggested that DM does not significantly increase the average length of
stay or the cost of hospitalization in patients with hip fractures, which were consistent with Nicholas' findings [19], This suggested that diabetes has no significant effect on length of stay, cost of stay, and 1-year mortality in patients undergoing hip fracture surgery. Although the difference in total hospital expenses was not statistically significant, the average total hospital expenses in DM group were slightly higher than those in non-DM group, possibly because the cost of blood glucose control was relatively low. However, these results are contrary to the results of Tian Wa-O et al. [17]. So larger samples and more rigorous clinical trials are still needed to produce more reasonable results.
Although in our study, the number of deaths within 1 year in DM group (12.9%, n = 8) was higher than that in non-DM group (9.7%, n = 6), there was no statistical difference between two groups (P = 0.57). Two previously published studies have also reported that the presence of DM does not negatively impact survival following hip fracture surgery [20, 21]. Whether the presence of DM increases the 1-year mortality in patients with hip fractures is inconclusive and requires further studies.
The advantage of this study is that partial confounding factors were eliminated by the method of PSM, making the results more representative. At the same time, this study also has some limitations. Firstly, some hip fracture patients admitted to our hospital did not receive surgical treatment, and the basic data and outcome indicators of conservative treatment were not analyzed in this study, so it was impossible to determine whether DM affects the outcome indicators of hip fracture patients who did not receive surgical treatment. Secondly, income level, body mass index and nursing factors were also factors affecting the prognosis of hip fracture in the elderly. The influence of these factors was not analyzed in this study. In addition, homogeneity and heterogeneity tests were not performed on the included samples, but there was no significant statistical difference in demographic and clinical characteristics between the groups after PSM, which was consistent with the requirements of general retrospective study.