According to research reports that can be retrieved so far, this study is the first comprehensive analysis of the application of POSSUM and P-POSSUM scoring systems to elderly hip fractures. In terms of the results of this study, the POSSUM scoring system can accurately predicted the postoperative morbidity (RR=1.07,95%CI:0.93-1.24), and compared with POSSUM over-predicted the mortality (RR=1.93, 95%CI:1.21-3.08), P-POSSUM can accurately predict the postoperative mortality of elderly patients with hip fractures(RR=1.15 ,95%CI 0.89-1.50).
In a meta-analysis report on the application value of POSSUM scoring system in hepatobiliary and pancreatic surgery by Chen et al , they believe that because the early POSSUM scoring model is not suitable for current surgical operations, it led to POSSUM’s over-prediction of postoperative morbidity and mortality. Similarly, we also believe that the same situation may exist here. The POSSUM scoring system proposed by Copeland et al in 1991 was originally used for general surgery patients. It was used in orthopedics after Mohamed et al modified its surgical scoring table according to the characteristics of orthopedic surgery in 2002. In the past 18 years, surgical methods and instruments have been greatly improved, and the nursing teams in related departments have become more professional. Previous improvements according to the characteristics of orthopedic surgery are no longer applicable to the current postoperative risk assessment. And, with the development of surgical technology, the impact of surgical intervention on the prognosis of patients is getting smaller and smaller. Combining the characteristics of high incidence of hip fracture in the elderly patients and having many underlying diseases in this group of people, it is not enough to modify the surgical severity score scale alone, and the physiological score scale should also be specifically modified. Orthopedic patients, especially those with hip fractures, have a tendency to stay in bed for a long time, which leads to a high risk of venous thrombosis. The physiology score scales, such as coagulation function, D-dimer, and other auxiliary examinations such as neck and lower extremity vascular color Doppler ultrasound to assess the patient's vascular condition, have not been reflected in the score.
Secondly, some studies reported that the difference in the prediction by POSSUM on the morbidity and mortality may be caused by the difference in the medical technology level, population characteristics, and the composition ratio of patient operation types in the non-originating country of the system from the originating country of the system . In the process of exploring the source of heterogeneity of combined results in this study, we found that the type of hip fracture, the choice of surgical methods, and the distribution of patient age may all have an impact on the prediction accuracy of the POSSUM scoring system. Because the treatment methods of different fracture types are often different, the prognosis is naturally very different; and advanced surgical methods and young patients show a lower risk of postoperative death and complications. In addition, the POSSUM score of elderly patients may have false score values. For example, a study by Ramanathan et al  found that elderly people older than 80 years old are abnormal compared to normal people because the relevant test results are "normal" for themselves, which leads to the inability of the POSSUM score to accurately predict the postoperative complications rate and mortality of this group of people. That is, POSSUM gives an excessively high score for the "normal" physiological examination results that can maintain the physiological function of this group of people. Therefore, this group of population may not be suitable for POSSUM scoring system, a two-component scoring model of preoperative physiology score and surgical severity score. We believe that the above problems may be solved by risk grouping based on the size of the POSUUM score value. From previous reports, it can be seen that the error of POSSUM's over-predicting postoperative death events mainly comes from the low-risk group. For example, in the reports of Whiteley et al  and Prythech et al , The predicted value of death event the low-risk group was 6 times and 7 times of the actual observation value, and POSSUM performed well in the high-risk group. Therefore, we believe that it is necessary to improve the predictive ability of the POSSUM scoring system in the complication rate and mortality of patients with hip fractures, and it is very necessary to predict the risk of patients when using the scoring system.
One of the shortcomings of this study is that although our study was analysed in subgroups, we did not find a major source of heterogeneity in the POSSUM-predicted postoperative mortality pairs. We suspect that this may be due to differences in the cause of the fracture, the physical impact of the fracture itself, the treatment, the distribution of the population, and the level of medical care, but we were unable to draw firm conclusions. In addition, this study also failed to collect relevant unpublished data.
In all, the current data analysis shows that the POSSUM scoring system can predict the postoperative morbidity of elderly hip fracture patients. POSSUM's prediction of mortality is affected by the type of fracture and size of sample. Compared with POSSUM, P-POSSUM can accurately predict the postoperative mortality of patients with hip fractures. The application of the POSSUM scoring system in orthopedics needs to be further improved according to the characteristics of orthopedic patients and surgery, as well as needing more multi-center and large-sample prospective studies, so that it can be more applicable to orthopedics.