Original Research

Risk Factors for Discharge to Rehabilitation Among Hip Fracture Patients

Am J Orthop. 2015 November;44(11):E438-E443

Length of stay (LOS) drives costs for hip fracture patients. One factor that affects LOS is delayed transfer of patients to rehabilitation centers. It is therefore imperative that orthopedists have a mechanism for identifying which patients require rehabilitation services after surgery.

We conducted a study to identify patient risk factors that are significantly associated with discharge to rehabilitation. Using 2011 ACS-NSQIP (American College of Surgeons National Surgical Quality Improvement Program) data, we prospectively analyzed the cases of 4815 patients who underwent hip fracture surgery and had discharge information available. Discharge location, surgery type, patient demographics, 32 patient comorbidities, and 7 operative factors were identified in these patients. Fisher exact tests were used to determine which patient factors were significantly associated with discharge to rehabilitation.

Of the 4815 patients, 80.3% were discharged to rehabilitation and 19.7% to home. After multivariable analysis, age over 65 years, female sex, dialysis, prior percutaneous coronary intervention, hypertension, general anesthesia, and ASA (American Society of Anesthesiologists) class higher than 2 had higher odds of discharge to rehabilitation, and DNR (do not resuscitate) status had higher odds of discharge to home.

This study was the first to determine which factors predicted discharge to rehabilitation in hip fracture patients. Knowing these risk factors provides orthopedists with a mechanism that can be used to identify which patients require rehabilitation after surgery, thereby facilitating transfer and potentially decreasing LOS and associated costs.

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References

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Length of stay (LOS) is a significant driver of costs after hip fracture surgery.^1-3 Multiple studies have identified factors associated with increased LOS in hip fracture patients. These factors include admission time, delay to surgery, presence of comorbidities, and older age.^4-9

One significant and potentially modifiable factor affecting LOS is delayed transfer to a rehabilitation center after surgery.^8-11 Although patients after orthopedic surgeries require additional rehabilitation services or subacute care directly attributable to their injuries, specialized rehabilitation centers may not always have beds readily available.^6-11 Studies have shown that delays in transfer to skilled nursing facilities or rehabilitation centers are highly common among orthopedic patients.⁸ It is therefore imperative that orthopedists have a mechanism for predicting and identifying which patients require rehabilitation services early in the postoperative period. Identifying risk factors and stratifying patients who are most likely to require rehabilitation would facilitate the early transfer of these patients and thereby directly decrease LOS and hospitalization-related costs.

In this article, we report results from prospective, national, multicenter data to identify commonly measured risk factors for discharge to rehabilitation facilities for hip fracture patients. Through multivariate analysis of ACS-NSQIP (American College of Surgeons National Surgical Quality Improvement Program) data, we determined which risk factors significantly predispose patients to discharge to rehabilitation centers versus discharge home. Knowledge of these risk factors allows the practicing orthopedist to be better equipped to identify patients who require additional rehabilitation early in the postoperative course. By mobilizing case managers and social workers to help avoid delays in the transfers of these identified patients, LOS-associated costs may ultimately decrease.

Materials and Methods

After obtaining institutional review board approval for this study from the Office of Research at Vanderbilt University, we prospectively collected 2011 discharge data from the ACS-NSQIP database (these data are unavailable for earlier years). All patients who underwent hip fracture surgery in 2011 were identified by CPT (Current Procedural Terminology) codes. Cases of patients with unknown discharge information and of those who died during their hospitalizations were excluded from analysis. For the remaining patients, discharge information as categorized by ACS-NSQIP included skilled care (eg, subacute hospital, skilled nursing home), unskilled facility (eg, nursing home, assisted facility), separate acute care, and rehabilitation. All other patients were discharged home without additional assistance or to the previous home where they received chronic care, assisted living, or unskilled aid. Patients were dichotomized according to whether they were discharged home or to one of the rehabilitation facilities mentioned.

To determine which risk factors significantly contributed to a patient’s discharge to rehabilitation, we ran univariate analyses using Fisher exact tests for categorical variables and Student t tests for continuous variables on multiple patient factors, including demographics, preoperative comorbidities, and operative factors. Demographics included age and sex. Preoperative comorbidities included 32 conditions: diabetes mellitus, active smoking status, current alcohol use, dyspnea, history of chronic obstructive pulmonary disease, history of congestive heart failure, hypertension requiring medication, history of esophageal varices, history of myocardial infarction, current renal failure, current dialysis dependence, steroid use, recent weight loss, existing bleeding disorder, transfusion before discharge, presence of central nervous system tumor, recent chemotherapy, recent radiation therapy, previous percutaneous coronary intervention, previous percutaneous coronary stenting, history of angina, peripheral vascular disease, cerebrovascular accidents, recent surgery (within 30 days), rest pain, impaired sensorium, history of transient ischemic attacks, current hemiplegia status, current paraplegia status, current quadriplegia status, current ascites, hypertension, and disseminated cancer. Operative factors included wound infection, DNR (do not resuscitate) status, ventilator support, anesthesia type, wound class, ASA (American Society of Anesthesiologists) class, and operative time.

For the univariate analyses, significance was set at P < .05. Demographics, preoperative comorbidities, and operative factors that were significantly associated with discharge to a rehabilitation facility in the univariate analysis were selected as covariates for a multivariate analysis. We incorporated a binary logistic regression to analyze which of these significant risk factors are correlated with a patient’s discharge to a rehabilitation facility after hip fracture surgery.

Results

A total of 4974 patients undergoing surgery for hip fractures in 2011 were identified. Of these patients, 4815 had complete information on discharge location and were included in the analysis.

Table 1 lists the results of the univariate analysis comparing demographics, preoperative comorbidities, and operative factors between the home and rehabilitation groups. Both age (P < .001) and sex (P = .012) were significantly different between groups; the rehabilitation group was older by about 10 years and included significantly more females. In addition to demographic factors, 16 preoperative comorbidities, and 5 surgical factors were significantly associated with discharge to rehabilitation.