LENGTH OF STAY AND FUNCTIONAL IMPROVEMENT AMONG PATIENTS ADMITTED

OBJECTIVE: To identify factors predictive of length of stay (LOS) and the level of functional improvement achieved among patients admitted to an acute rehabilitation unit for the first time, with special reference to the role of nosocomial infection. SETTING: A 40-bed acute rehabilitation unit within a 300bed, tertiary-care, public, university-affiliated hospital. STUDY POPULATION: All patients admitted to the unit between January 1997 and July 1998. DESIGN: Prospective cohort study in which demographic and clinical data, including occurrence of nosocomial infection, were collected during the entire unit admission of each patient. Multivariate linear regression analysis was used to identify factors predictive of unit LOS or improvement in functional status as measured by the change in the Functional Independence Measure (FIM) score between admission and discharge (AFIM). RESULTS: There were 423 admissions to the rehabilitation unit during the study period, of which 91 (21.5%) had spinal cord injury (SCI) as a principal diagnosis. One hundred seven nosocomial infections occurred during 84 (19.9%) of the 423 admissions. The most common infections were urinary tract (31.8% of all infections), surgical-site (18.5%), and Clostridium difficile diarrhea (15%). Only one patient died of infection. After controlling for severity of illness on admission, functional status on admission, age, and other clinical factors, the significant positive predictors of unit LOS were as follows: SCI (f<.001), pressure ulcer (.002), and nosocomial infection (<.001). Significant negative predictors of AFIM were age (P<.001), FIM score on admission (<.001), prior hospital LOS (.002), and nosocomial infection (.007). CONCLUSIONS: Several variables were identified as contributing to a longer LOS or to a smaller improvement in functional status among patients admitted for the first time to an acute rehabilitation unit Of these variables, only nosocomial infection has the potential for modification. Studies of new approaches to prevent infections among patients undergoing acute rehabilitation should be pursued (Infect Control Hosp Epidemiol 2001;22:83-87). Nosocomial infection is common among patients admitted to acute rehabilitation units or facilities for intensive physical rehabilitation after traumatic and nontraumatic neurological injury, traumatic injuries that are of a nonneurological type, or general deterioration (deconditioning) after a debilitating illness. Among patients admitted to these units, those with spinal cord injury (SCI) have a significantly higher rate of nosocomial infection than those without spinal cord injury (non-SCI). ' SCI also is a unique predictor of nosocomial infection among patients admitted for the first time to an acute rehabilitation unit. Studies of hospitalized patients have found that nosocomial infection prolongs hospital stay and increases cost of care. In addition, nosocomial infections occurring among hospitalized patients often are serious and life-threatening. In contrast, nosocomial infections occurring among patients admitted to acute rehabilitation units after acute hospitalization tend not to be life-threatening. However, the morbidity of nosocomial infection among patients admitted to acute rehabilitation units has not been evaluated. We recently described the epidemiology of nosocomial infections among patients admitted for the first time to an acute rehabilitation unit of a university-affiliated hospital during a 19-month period. The objective of the present report is to describe the results of an analysis to identify factors predictive of two important outcomes for this patient population: length of stay (LOS) and the level of functional improvement achieved at the time of discharge from the rehabilitation unit. In this analysis, we were particularly interested in the influence of nosocomial infection on these outcomes, because these infections may be preventable to some degree. M E T H O D S Setting This study was performed at the Erie County Medical Center (ECMC), a 300-bed, university-affiliated, From the Departments of Medicine (Dr. Mylotte; Ms. Kahler and Ms. Goodnough); Microbiology (Dr. Mylotte); and the Office of Research and Development, Department of Family Medicine (Dr. Graham; Ms. Young); School of Medicine and Biomedical Sciences (Drs. Mylotte and Graham; Ms. Young), University at Buffalo, Buffalo, New York. Address reprint requests to Joseph M. Mylotte, MD, CIC, Infectious Diseases, Erie County Medical Center, 462 Grider St, Buffalo, NY 14215. This study was supported by the Spinal Cord Research Foundation of the Paralyzed Veterans of America (grant 1687-01 and 1687-02). OO-OA-106. Mylotte JM, Graham R, Kahler L, Young BL, Goodnough S. Impact of nosocomial infection on length of stay and functional improvement among patients admitted to an acute rehabilitation unit. Infect Control Hosp Epidemiol 2001;22:83-87. 84 INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY February 2001 public hospital located in Buffalo, New York. ECMC provides primaryand tertiary-care facilities for the metropolitan Buffalo region. In addition to providing services to the indigent, ECMC has the only level I trauma unit and burn treatment unit in the area of New York State west of Rochester. The Department of Rehabilitation Medicine is responsible for a 40-bed acute rehabilitation unit at ECMC. This unit consists of two 20-bed wings that share a common nursing station and staff. Contained within this unit is a 10-bed SCI unit. Design This was a prospective cohort study of patients admitted to the acute rehabilitation unit at ECMC during the 19-month period between January 1997 and July 1998. A research nurse reviewed each patient's chart at the time of admission and weekly thereafter during the entire inpatient stay. Data collected included demographic information; underlying diseases; reason for admission to the unit; medications prescribed, including antibiotics; acute severity of illness at the time of admission (using the Acute Physiology and Chronic Health Evaluation [APACHE] III scoring system); severity of disability at the time of admission and discharge, as measured by the Functional Independence Measure (FIM); and nosocomial infection. Data were collected on forms specifically designed for this study. This study was approved by the State University of New York at Buffalo School of Medicine and Biomedical Sciences Institutional Review Board. Patients All patients admitted to the acute rehabilitation unit at ECMC for intensive physical rehabilitation during the study period were included in this study. Definitions SCI group. Patients were categorized as having SCI (n=91) if this was the primary diagnosis at the time of admission to the acute rehabilitation unit at ECMC. Patients who had no evidence of any spinal cord impairment were categorized as the "non-SCI" group for the purposes of this study. Of the 332 episodes in the non-SCI group, the most common reasons for admission were categorized as traumatic brain injury (24.6%), acute stroke (19.4%), multiple traumatic injuries (16.4%), deconditioning (12.4%), subarachnoid hemorrhage (10.6%), cancer (0.3%), and miscellaneous (16.3%). For almost 90% of the patients, it was their first admission for acute rehabilitation after an acute hospital stay. Nosocomial infection. An infection was defined as nosocomial if it was identified more than 72 hours after admission to the rehabilitation unit and there was no evidence of incubating infection on admission. Nosocomial infections were identified using Centers for Disease Control and Prevention criteria, except for urinary tract infection; definitions for urinary tract infection were those of Gribble and Puterman. Details of the epidemiology of nosocomial infection in the study population have been published previously. Dependent Variables Length of stay on the rehabilitation unit was defined as the date of discharge minus the date of admission. Functional improvement was defined as the FIM score on discharge minus the score on admission to the unit (AFIM). Because higher FIM scores indicate better functional status, the AFIM was expected to be positive for patients discharged from the unit. Statistical Analysis Standard bivariate tests on association between a variety of independent variables and LOS and AFIM were conducted. Student's t test was applied to continuous variables; categorical variables were analyzed by Pearson's chi-square test. Multiple linear regression analysis was applied to the identification of predictors of LOS and AFIM. The regression model was constructed via forward entry of predictors. RESULTS During the 19-month study period there were 423 admissions to the rehabilitation unit, of which 91 (21.5%) had a primary diagnosis of SCI. During 84 (19.9%) of the 423 admissions to the rehabilitation unit, 107 nosocomial infections occurred. The detailed epidemiology of these nosocomial infections has been published and will be summarized only briefly in mis report. The overall incidence of nosocomial infection was 6.85 episodes per 1,000 patient-care days. Nosocomial infection occurred in a significantly greater proportion of SCI admissions (31.9%) than non-SCI admissions (16.6%; P=.001). The most common infections were urinary tract infection (34 [31.8%] of 107 infections), followed by surgical-site infection (18.5%), Clostridium difficile diarrhea (15%), and bloodstream infection (13.1%). All nosocomial infection patients but one survived to be discharged. LOS For 423 admissions to the rehabilitation unit, the mean (±standard deviation) LOS was 37±35 (median, 26; range, 2240) days. Variables included in the analysis of predictors of LOS were occurrence of nosocomial infection, demographic characteristics, underlying diseases, SCI, invasive devices, antibiotic treatment on admission, and presence of a pressure ulcer. Significant bivariate predictors of LOS are noted in Table 1, along with