In this study, we investigated 16 potential factors and found that 9 factors were associated with a prolonged LOS, including postoperative complications, the patient’s age, the clinical protocol, intraoperative blood loss, the operative time, the surgeon, the ward, the ASA classification, and neurological comorbidities.
Complications were also found to be a contributing factor for prolonged LOS in previous studies [7, 8]. Patients in our centre were not allowed to be discharged from the hospital once complications such as DVT and infection occurred unless the complications were controlled.
Patients in ward A tended to have shorter hospital stays than those in ward B, which is in accordance with the findings in a previous study . In our department, ward A had more trained therapists and surgeons, which partly explains the faster turnover of patients in ward A.
Consistent with the results of other studies, the older group of patients (> 65 years) was likely to stay in the hospital longer than the younger group (≤65 years) [7, 18,19,20]. Older patients tend to be in worse physical condition and more likely to have postoperative complications [21, 22], which increases the LOS. Furthermore, older patients are more likely to live alone and need caregiver support than are younger patients, and these factors have been shown to be important predictive factors for an extended LOS .
The ASA classification is frequently used to define patients’ physical condition [11, 13]. It is reasonable to conclude that patients with ASA III/IV often stay longer than those with ASA I/II, as they require much more time to reach the strict discharge criteria. Additionally, we assessed the influence of comorbidities and found that neurological comorbidities can prolong hospital stays. We speculate that neurological diseases make it difficult for patients to exercise soon after surgery. In contrast to the results of other literature, we did not find a statistically significant association between cardiopulmonary disease and prolonged LOS, which may be due to the small sample sizes.
Beginning in 2014, a new clinical protocol was implemented in our department. Comparing with the traditional clinical protocol, the new one is more reasonable and sound owning to the improvement of some perioperative management protocol, including building a new rehabilitation team and introducing a “cocktail pain control” model. In this study, we investigated whether a good perioperative protocol can change patients’ LOS. Our results showed that people stayed in the hospital for a much shorter period when the protocol was implemented in patients who received TKA surgery. Thus, hospitals in developing countries should develop sound perioperative management plans to shorten LOS and increase the medical resource utilization rate.
We found that a longer operative time is positively correlated with a prolonged LOS, which is in accordance with the results of a study by Ifeoma et al. . An explanation for this result might be that a tourniquet is routinely used for patients undergoing TKAs in our institution. Therefore, when the operative time increased, the tourniquet time increased accordingly. The hypoxia-ischaemia induced by the use of tourniquet may result in the swelling of soft tissue, weakened strength of the quadriceps muscle and pain in the thigh [23, 24], which slows early rehabilitation training and consequently leads to a prolonged LOS; another explanation may be the positive correlation between a prolonged operative time and an increased infection rate after TKAs .
We found that increased intraoperative blood loss is associated with a prolonged LOS, which has not been previously reported. A possible reason for this correlation may be that the loss of blood during an operation can make patients feel weak and make it difficult for them to perform early physical exercise.
In this study, we found that surgeons have a positive effect on LOS following TKA, which is consistent with the finding of Monsef et al. . A possible explanation for this result may be that surgeons had different experiences in managing patients during the perioperative period. Additionally, they may have been relaxed or firm when determining whether the patients should be discharged.
In reality, patients’ decisions may affect LOS because they have the right to decide when to leave hospital. However, it is difficult for us to record patients’ preferences and analyse these data. The patients who want stay in the hospital for a longer period may have common traits, such as being discharged to their home, living alone and having no caregiver support, which have been suggested as predictors of a prolonged LOS . Unfortunately, in our database, this information was not recorded. We hope that these patient-related variables will be analysed in the future.
There is no consensus on the contribution of sex to a prolonged LOS. Some researchers have found that females tend to have a longer LOS than males [6, 11, 27]. The authors explained that females are more likely to have higher rates of obesity, postoperative transfusion and postoperative complications. However, some studies did not find statistically significant differences in LOS between the two groups [10, 12]. Similarly, in our study, the difference between males and females was not obvious. However, this result may be caused by the unbalanced sex ratio (1:3). Therefore, more studies should be performed to investigate the effect of sex on LOS. In addition to sex, other variables such as the BI score, the VAS score, ROM, the day of operation, and transfusion were not associated with prolonged LOS in our study.
There are some limitations to this study. First, we split continuous variables into groups based on the sample mean, which is the most common approach used in the literature. Information loss is inevitable, and therefore, the statistical power to detect a correlation may have been weakened. Second, we extracted all data from medical records, and the data for several factors, such as the VAS score, ROM and intraoperative blood loss, may not be accurate; however, bias can be accommodated due to the large sample size. Third, all of the patients analysed were from our institution; thus, the result may not be representative of all hospitals in China.
Despite the above limitations, this study has important clinical value for several reasons. First, this is the first article to explore the association between perioperative variables and LOS following TKAs in China. Moreover, we found nine factors that positively contribute to a prolonged LOS. This result is reliable and meaningful because of the high quality of our centre compared with other orthopaedic clinics in China and the large sample size in this study, even though this is a single-centre study. In addition, all of the data in our study were collected from medical records rather than from a database. Therefore, we could investigate some variables that cannot be retrieved via procedural codes. Finally, 16 variables were included in the present study, which is much more than the number of variables included in other similar studies. Importantly, the sample size was sufficiently large to generate a reliable statistical outcome. Although fast-track protocols are prevalent in developed countries, the long LOS model is common among developing countries [7, 8]. Therefore, it is essential to explore factors that can potentially reduce the LOS following TKAs in developing countries.