This study shows that frailty rate of joint replacement was only 2.5%, which is consistent with the results of McIsaac et al.. However, the incidence rate is also far lower than that for other surgical operations, which range from 8–28%, possible because the high rates of frailty comprised only older adults[3].
Our study found that frailty was significantly associated with advanced comorbidity (CCI ≥3). This reflects that among patients undergoing TJA, those who are frial before surgery do easily have combined with comorbidities. This may also be related to the comorbidity being a major cause of frailty. We further found that frailty was significantly associated with in-hospital death, and surgical complications, while comorbidity was not an independent predictor for in-hospital death and surgical complications, the interaction between frailty and comorbidity was not significant, suggesting that comorbidity did not affect the state of frailty during the short term perioperative period. This means that in the preoperative assessment of patients who are frail before surgery, there is no need to afraid that whether the comorbidities may increase the risk of frailty postoperative in-hospital death and postoperative surgical complications. Although both frailty and comorbidity could independently predict medical complications, comorbidities have a greater impact on medical complications. The interaction between frailty and comorbidity was also not significant, Therefore, When considering postoperative medical complication, more attention should be paid to comorbidity.
There was a synergistic interaction between frailty and comorbidity for length of stay and hospitalization costs. Generally speaking, costs and LOS of the patient with non-frailty is far less than that of frailty (figure 2a and 2b). Interestingly, the combined predictor, frailty, CCI=0, had a greater influence on the length of stay and hospitalization costs than the other predictor that CCI≠0, This suggests that for people without comorbidities, frailty is easy to be neglect by doctors, which will made patient cost more in hospital.
This study has some limitations. Due to the limitations of the NIS database, the study could not fully examine the effect of frailty on patients who underwent TJA. For example, the long-term complications or re-admission indicators were not included in the database. Moreover, the specific mechanism of the effect of frailty on particular difficulties associated with TJA requires further investigation. Frailty did not stratify according to different severities such as the Clinical Frailty Scale because of the limitations of the database.
Nevertheless, this study demonstrates the importance of frailty in joint replacement surgery.
Frailty and comorbidities are often present in patients concurrently; however, frailty is independent of comorbidities and has an impact on the postoperative complications associated with joint replacement. From the perspective of the synergistic interaction between frailty and comorbidities in hospitalization costs and length of stay, frailty is a factor that requires consideration for joint replacement.
When doctors understand the contributions and interactions of frailty and comorbidity, they can optimize the patient’s status before surgery. Regarding the patients with multiple comorbidities, the doctor should consider multi-drug therapy to prevent acute medical complications or balance the advantages and disadvantages of the risk of comorbidities and the benefits after TJA. Yet, for patients with frailty who undergo TJA, interventions to treat frailty should be a priority. Most importantly, it is vital to strengthen nutritional reserves to improve the patient’s ability to respond to surgery. For instance, similar to nutrient-dense fluids, oral nutritional supplements can be provided to patients with frailty. Administration of oral nutritional supplements shows a decrease in the mortality rate for hip fractures[14].Second, early treatment with vitamin D in the range of 200–1000 IU could reduce falls, and improve muscle and nerve function[14] Finally, exercise is an essential part of the treatment for frailty. Progressive strength training before surgery has been deemed the key exercise for patients with frailty[15].