Rehospitalization After Traumatic Brain Injury - Archives of Physical ...

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Archives of Physical Medicine and Rehabilitation journal homepage: www.archives-pmr.org Archives of Physical Medicine and Rehabilitation 2016;97(2 Suppl 1):S19-25

ORIGINAL RESEARCH

Rehospitalization After Traumatic Brain Injury: A Population-Based Study Cristina Saverino, MA,a,b,c Bonnie Swaine, PhD,d Susan Jaglal, PhD,c,e John Lewko, PhD,f Lee Vernich, MSc,g Jennifer Voth, PhD,c Andrew Calzavara, MSc,h Angela Colantonio, PhD, OTc,h,i From the aDepartment of Psychology, University of Toronto, Toronto, ON; bRotman Research Institute, Baycrest, Toronto, ON; cToronto Rehabilitation Institute-University Health Network, Toronto, ON; dSchool of Rehabilitation, Faculty of Medicine, University of Montreal, Montreal, QC; eDepartment of Physical Therapy, University of Toronto, Toronto, ON; fCentre for Research in Human Development, Laurentian University, Sudbury, ON; gDalla Lana School of Public Health, University of Toronto, Toronto, ON; hInstitute for Clinical Evaluative Sciences, Toronto, ON; and iDepartment of Occupational Science and Occupational Therapy, University of Toronto, Toronto, ON, Canada.

Abstract Objective: To examine, from a Canadian population-based perspective, the incidence and etiology of long-term hospital utilization among persons living with traumatic brain injury (TBI) by age and sex. Design: Retrospective cohort study. Setting: Acute care hospitals. Participants: Index cases of TBI (NZ29,269) were identified from the Discharge Abstract Database for fiscal years 2002/2003 through 2009/ 2010 and were followed-up until 36 months after injury. Interventions: Not applicable. Main Outcome Measures: Rehospitalization was defined as admission to an acute care facility that occurred up to 36 months after index injury. Diagnoses associated with subsequent rehospitalization were examined by age and sex. Results: Of the patients with TBI, 35.5% (nZ10,390) were subsequently hospitalized during the 3-year follow-up period. Multivariable logistic regression (controlling for index admission hospital) identified men, older age, mechanism of injury being a fall, greater injury severity, rural residence, greater comorbidity, and psychiatric comorbidity to be significant predictors of rehospitalization in a 3-year period postinjury. The most common causes for rehospitalization differed by age and sex. Conclusions: Rehospitalization after TBI is common. Factors associated with rehospitalization can inform long-term postdischarge planning. Findings also support examining causes for rehospitalization by age and sex. Archives of Physical Medicine and Rehabilitation 2016;97(2 Suppl 1):S19-25 ª 2016 by the American Congress of Rehabilitation Medicine

Supported by the Ontario Neurotrauma Foundation (grant no. 2006-ABI-RTBI-432); Ontario Neurotrauma Foundation-Re´seau provincial de recherche en adaptation-re´adaptation (grant no. ONF-2011-ONF-REPAR2-883); the Toronto Rehabilitation Institute; the Institute for Clinical Evaluative Sciences, which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care; and a Canadian Institutes of Health Research Research Chair in Gender, Work and Health (grant no. CGW-126580) from the Institute of Gender and Health. The opinions, results, and conclusions reported in this article are those of the authors and are independent from the funding sources. No endorsement by the Institute for Clinical Evaluative Sciences or the Ontario Ministry of Health and Long-Term Care is intended or should be inferred. Publication of this article was supported by the American Congress of Rehabilitation Medicine. Disclosures: none.

Traumatic brain injury (TBI) is a major cause of death and disability in the United States. Approximately 1.7 million people will sustain a TBI each year in the United States, resulting in 1.4 million emergency department visits, 275,000 hospitalizations, and 52,000 deaths.1 The economic costs associated with TBI, including direct medical and rehabilitation costs and indirect societal costs, are estimated to be $60 billion in the United States.2 Recurrence of hospitalization (ie, rehospitalization) is a common problem among individuals with a chronic condition or injury and is associated with increased health care costs and reduced health care quality.3-5 A reported 15% of individuals with chronic

0003-9993/15/$36 - see front matter ª 2016 by the American Congress of Rehabilitation Medicine http://dx.doi.org/10.1016/j.apmr.2015.04.016

S20 conditions (eg, stroke, TBI, hip fracture) were readmitted to hospital within 2 months after discharge.6 Those who suffered from an injury had an increased risk of reinjury.7 Older age, being a man, greater injury severity,7,8 and longer initial length of stay9,10 were associated with higher rates of readmission, with most readmissions being the result of congestive heart failure and chronic obstructive pulmonary disease.9,11 These trends, however, apply to a diverse population with various conditions and may not necessarily generalize to patients with a TBI. Persons with TBI have higher rates of readmission and are more likely to incur subsequent injuries compared with nonbrain injured controls, with numbers ranging from 16% to 18% at 6 months,12,13 17% to 20% at 1 year,13,14 and 20% to 23% over a 3year period.15 Similar rates of rehospitalization have been established at 5 years postinjury, with a trend toward elective surgery early on and general health maintenance after the first year.16 Children and adults who sustained a TBI also appear more likely to sustain another injury at 1- and 10-year follow-up, respectively, compared with nonbrain injured controls.17,18 Previous studies, however, have examined patients with TBI who were discharged from selected trauma12,13 or rehabilitation centers,14-16 which predominately treat a small segment of moderate to severe cases and are likely affected by attrition.12-16,19 A subset of these studies was based on U.S. data,15,16 and those conducted in Canada are limited to a specific age group17,18 or include only unplanned readmissions.12,13 Consequently, the aim of the current study was to investigate, from a Canadian population-based perspective, the incidence and etiology of all rehospitalizations among those who sustained a TBI at 1- and 3-year follow-up times. Given that the incidence rates of TBI vary by age and sex,19,20 rehospitalization rates were stratified by these factors.

Methods Participants Participants included in this retrospective cohort study were patients discharged alive from Ontario hospitals between April 1, 2003, and March 31, 2010 (fiscal years 2002/2003e2009/2010) for a TBI. Patients with a TBI were identified from acute care hospitalization records using the following International Classification of Diseasese10th RevisioneCanadian Enhancement (ICD-10-CA) injury codes: a fracture of the skull and facial bones (S02.0, S02.1, S02.3, S02.7, S02.8, S02.9), injury to the optic nerve and pathways (S04.0), intracranial injury (S06.0eS06.9), or crushing injury of the head (S07.0eS07.9). To ensure integrity of the incident cases, patients were excluded from analyses if they sustained a TBI the year prior to their index injury. A 1-year clearance is consistent with prior studies that investigate readmissions after injury.8,17 Further exclusion criteria included patients who died in hospital from the index TBI, patients who resided outside of Ontario, and patients whose records contained

List of abbreviations: ADG Aggregated Diagnosis Group DAD Discharge Abstract Database ICD-10-CA International Classification of Diseasese10th Revisione Canadian Enhancement MVC motor vehicle collision TBI traumatic brain injury

C. Saverino et al unspecified sex information or erroneously recorded date of death. Ethics approval was received from the Toronto Rehabilitation Institute and Institute for Clinical Evaluative Sciences.

Data sources Hospital admission data were accessed at the Institute for Clinical Evaluative Sciences using the Canadian Institute of Health Information Discharge Abstract Database (DAD),21 which contains information on the following variables: age, sex, residential postal code, date of admission, date of discharge, primary ICD diagnostic codes, and secondary and tertiary ICD diagnostic codes. Index cases of TBI were identified from the DAD using data from 141 hospitals (ranging in size from 1 to 2743 patients being treated per institution). Excellent agreement for primary diagnoses has been found between administrative hospitalization data and chart audit.22 The Registered Persons Database was used to identify mortality information of participants. It contains the date of birth and cause and date of death of all persons with a valid Ontario Health Card. Patients were linked via unique encoded identifiers and analyzed at the Institute for Clinical Evaluative Sciences (100% match).

Variables Information was extracted from the DAD and Registered Persons Database and categorized based on preinjury, injury, and postinjury study variables. Preinjury variables Demographic information (eg, age at the time of initial injury, sex, rurality) was collected. Age was divided into 5 groups: children (65y). Rural versus nonrural residence was determined using postal codes from administrative databases.23 Injury variables Variables collected at the time of injury included mechanism of injury, Abbreviated Injury Score,24 initial length of acute care stay based on the duration of the index hospitalization, comorbidity, and psychiatric comorbidity. The mechanisms of injury were identified using injury codes and grouped into 4 major categories: falls, motor vehicle collision (MVC), struck by/against, and other mechanism of injury. Discharge destination was also examined to describe the cohort. In Ontario, patients may be discharged to another facility, transferred to long-term care or ambulatory/palliative care, or discharged home with or without services. Rehabilitation can occur in acute care hospitals and/or at freestanding inpatient rehabilitation hospitals. Year of injury was added to multivariable models to control for practice changes over time. The Abbreviated Injury Score was used as a measure of TBI severity. Severity was measured on a 6-point scale and categorized as mild (1e2), moderate (3), or severe (4) injury. If a patient had >1 diagnosis of TBI on their hospital record, the injury with the highest severity was used to classify the severity. The Johns Hopkins Adjusted Clinical Group Case-Mix System was used to account for patient comorbidity.25-27 This method of adjusting for case mix has previously been used in Canada28 and has been validated in the United States.29 The system uses individual-level data to assign measures of resource use and comorbidity from diagnoses during a specified time period, obtained from patient records. In the present study, the Adjusted Clinical Group algorithm used physician billing claims from the www.archives-pmr.org

Rehospitalization after TBI Ontario Health Insurance Plan administrative database and hospital admissions from 2 years prior to index to determine a comorbidity score for patients equal to the sum of the Aggregated Diagnosis Group (ADG) indicators. Psychiatric comorbidities were additionally examined as a separate variable. Outcome variables Transfers between facilities for the incident TBI were censored to minimize the potential for misclassifying readmissions. Therefore, for this analysis, patients with incident TBI between fiscal years 2002/2003 and 2009/2010 were followed-up from 4 days after the initial acute care discharge until March 31, 2013, to identify readmission to an acute care facility for a hospital stay. Emergency department visits were not included as a hospital admission; however, a 1-night admission was included as an outcome variable. Participants were followed from index injury up to a maximum of 36 months. ICD-10-CA codes at admission were examined to identify causes of hospitalization and categorized according to ICD-10-CA chapter headings.

Data analyses Descriptive statistics of patient characteristics at time of index injury were stratified by age and sex. Rehospitalization rates were also stratified based on duration since index injury (1 vs 3y postTBI). A multivariable logistic regression model was run using a backward entry method to determine which variables contributed to the prediction of rehospitalization rates at 1 year and 3 years. Rehospitalization because of pregnancy/childbirth was not included in the model because this was not considered a negative health event. The models were fit using a generalized estimating equation (autoregressive correlation structure) to account for the correlation between rehospitalization and index admission hospital (nZ138; 3 hospitals had patients with only maternity outcomes). Adjusting by index hospital allowed for any undue influence related to the admission hospital (eg, common patient characteristics attending certain hospitals, differences in hospitals practices) to be covaried out of the models. Initial length of acute care stay was excluded from the model based on poor fit as determined by Hosmer-Lemeshow goodness of fit test. The Abbreviated Injury Score was the only measure of severity entered into the analyses. ADG was entered as a continuous and quadratic variable. Although the interaction term between age and sex was entered for both the 1-year and 3-year models, it was not significant and therefore was excluded from both analyses. A P value .05 was considered statistically significant. Analyses were performed using SAS version 9.3.a

Results Descriptive statistics There were 29,269 patients with TBI identified from the DAD records between fiscal years 2002/2003 through 2009/2010. Most patients with TBI were men (table 1). Falls were the most common mechanism of injury for patients 49 years of age, whereas patients between 15 and 49 years were, on average, more likely to sustain a TBI because of a MVC. Patterns were similar across men and women, with the exception that among the 25- to 49-year-old age group, falls and MVC were the most common

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S21 mechanisms of injury for men and women, respectively. The percentage of severely injured patients increased by age, as did the number of comorbid conditions. Most patients had no psychiatric comorbidity (96.5%) and lived in a nonrural setting (83.9%). Of the 29,269 patients with TBI, 22.9% (nZ6703) were rehospitalized within 1 year, and 35.5% (nZ10,390) were rehospitalized within the 3 years after index injury. As seen in table 2, percentages of rehospitalization increased steadily by age group. Although there were no sex differences in the number of rehospitalizations at 1 year, women between the ages of 15 and 49 years had a near 15% increase in the number of rehospitalizations relative to men at 3-years follow-up. Overall, the diagnoses most often reported at the time of rehospitalization were in the injury/poisoning ICD category. Poisoning is defined as a drug overdose (eg, poisoning by systemic antibodies, poisoning by other systemic anti-infectives and antiparasitics, poisoning by anesthetics and therapeutic gas). These were not intentional selfpoisonings that would have resulted from an attempted suicide. When stratified by age and sex, differences were observed in the causes of rehospitalization (table 3). Under the age of 15 years, boys were most likely to be readmitted because of injury/ poisoning (c21,909Z3.13, PZ.077), and girls were most likely to be readmitted for health status related to follow-up care (c21,909Z20.26, P