The patient variables that were significantly associated with discharge to rehabilitation are also associated with increased morbidity and mortality in hip fracture patients, according to the literature,14-20 which provides some external validation of using these risk factors as predictors for rehabilitation. A patient with one of these risk factors may require rehabilitation, given that rehabilitation services are specifically linked to lower morbidity and mortality rates among hip fracture patients. For example, patients with dialysis needs were 3.49 times more likely to be discharged to a rehabilitation center in our study. In a 2000 study by Coco and Rush,16 hip fracture patients on dialysis had a 1-year mortality rate 2.5 times higher than that of patients who were not dialysis-dependent. In 2010, Cameron and colleagues17 found that cardiovascular disease was associated with a 2.68 times higher risk of mortality in hip fracture patients. Similarly in our study, both hypertension and history of percutaneous coronary intervention were associated with discharge to rehabilitation. We found higher odds of discharge to rehabilitation with higher ASA classes, which mirror results from a study by Michel and colleagues,15 who found that higher (vs lower) preoperative ASA classes were associated with higher 1-year mortality in hip fracture patients. Interestingly, DNR status was associated with higher odds of discharge home, which may reflect patients’ desires to forgo noninvasive or lifesaving procedures that may be performed at rehabilitation facilities. Although general anesthesia predisposed patients to discharge to a rehabilitation center, multiple studies have found no association between anesthesia type and postoperative mortality rates for hip fracture patients.18,19 Last, Marcantonio and colleagues20 found delirium specifically had a higher odds ratio for discharge, but our univariate analysis did not find a significant association between impaired sensorium and discharge location. Given the correlation of our risk factors with increased morbidity and mortality in the literature, our study’s results provide the initial groundwork for creating a risk calculator that orthopedists can use to predict discharge to rehabilitation.
Our study had some limitations. Although we analyzed a large number of demographics, preoperative comorbidities, and surgical factors, our univariate analysis was limited to information in the ACS-NSQIP database. We did not incorporate other clinically relevant factors (eg, social factors, including patients’ support networks) that may influence discharge decisions. Furthermore, ACS-NSQIP records patient data only up to 30 days after surgery. Discharge information for the time after that was missing for a subset of hip fracture patients, and these patients had to be excluded, potentially skewing our data. ACS-NSQIP also does not collect cost data for patients based on hospitalization or LOS, so we could not determine whether patients discharged to rehabilitation incurred higher costs because of longer hospitalizations.
Nevertheless, our study identified significant patient and operative variables that are associated with discharge to a rehabilitation center. By identifying hip fracture patients with these risk factors early and mobilizing the appropriate resources, practicing orthopedists should be better equipped to help facilitate the discharge of patients to the appropriate location after surgery. Validation of these risk factors should be prospectively determined with an analysis of LOS and cost implications. Use of a risk calculator may in fact result in decreased LOS and hospital-related costs. Furthermore, using these risk factors in a prospective patient cohort would help validate their use and determine whether there is clinical correlation. The orthopedists in our institution are becoming more aware of these risk factors, but validation is necessary.