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To determine if nursing home (NH) resident characteristics associated with potentially preventable emergency department transfers (PPEDs) are similarly associated with non–potentially preventable emergency department transfers (non-PPEDs).
We conducted a population-level retrospective cohort study using linked administrative data reported using the Resident Assessment Instrument–Minimum Data Set Version 2.0 and the National Ambulatory Care Reporting System for emergency department transfers.
Setting and Participants
We assessed all NH residents transferred to the emergency department within 92 days after admission. The cohort included 56,433 NH resident admissions assessment of which 3498 NH residents experienced PPEDs, and 9331 residents experienced non-PPEDs.
We assessed Ontario NH residents admission assessments collected between January 1, 2017, and December 31, 2018. We used cumulative incidence functions and Cox regression to compare resident characteristics between residents experiencing PPEDs and non-PPEDs. PPEDs were defined based on the International Classification of Diseases, 10th Revision.
Approximately 23% of residents experienced an emergency department transfer within 92 days of NH admission. The cumulative incidence of PPEDs was 6.3% and non-PPEDs was 16.8%. After adjusting for clinically relevant features, 14 of 18 resident admission characteristics were associated with both types of transfers. Resident admission characteristics associated with a greater risk of PPEDs solely were pneumonia [hazard ratio (HR) 1.48; CI 1.25–1.70] and oxygen therapy (HR 1.88; CI 1.69–2.10). Resident admission characteristics associated with a greater risk of non-PPEDs solely are experiencing a change in mood (HR 1.09; CI 1.01–1.18) and delirium (HR 1.08; CI 1.04–1.13).
Conclusions and Implications
PPEDs were associated with a similar cluster of NH resident characteristics as those transferred for non-ambulatory reasons, suggesting that the clinical distinction between PPEDs vs non-PPEDs within the NH might be unclear. These findings highlight that the PPED indicator could be revised to improve specificity.
Nursing home (NH) residents are transferred to the emergency department (ED) for acute and emergent medical concerns. Approximately 20% to 40% of NH residents are transferred to the ED within 3 months of admission.
The definition of potentially preventable ED transfers (PPEDs) is based on the assumption that the primary presenting diagnosis could be prevented or managed in primary care, regardless of other factors such as age, interventions, and investigations completed in the ED.
Previously it has been assumed that identifying NH characteristics and residents at a higher risk for PPEDs can aid NHs in providing proactive and targeted prevention programs or reframing services in the facility, all efforts aimed toward reducing needless interfacility transfers for those at greatest risk.
Establishing an accurate diagnoses that correctly reflects the etiology of the reasons for presentation is challenging. Definitions of PPEDs are based on presenting diagnoses and may be more relevant to nonfrail patients with more predictable presentations. Previous literature demonstrates that the overall ability of prognostic models predicting PPEDs is poor, even when using the conditions that underlie the PPED definition as predictors.
We aim to examine the utility of the PPED definitions from the perspective of the NH by examining and comparing factors associated with PPEDs and non–potentially preventable ED transfers (non-PPEDs). Specifically, we aimed to determine if resident characteristics are uniquely associated with a greater risk for PPEDs rather than non-PPEDs.
Study Design and Data Sources
We conducted a retrospective cohort study analyzing data from all NH facilities across Ontario, Canada. Two population-level health administrative databases, the Continuing Care Reporting System (CCRS) and the National Ambulatory Care Reporting System (NACRS), were examined. These datasets were linked using unique encoded identifiers and analyzed at ICES. ICES stores health care data from various sources that are de-identified for analytic purposes.
The CCRS is a data repository of clinical assessments that are completed for each resident using the Resident Assessment Instrument–Minimum Data Set (RAI-MDS) 2.0.
Data were extracted from the RAI-MDS 2.0 admission assessment for each NH resident within 14 days of admission. The RAI-MDS 2.0 repository contains complete data on routine clinical assessment of NH residents throughout Ontario.
We followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) and the REporting of studies Conducted using Observational Routinely-collected health Data (RECORD) reporting guidelines for this study.
Residents admitted to an NH between January 1, 2017, and December 31, 2018, with a documented NH admission assessment were eligible for study inclusion. Residents were excluded if they had a missing ICES key number (used for data linkage across all databases), were classified as short-stay residents (<90-day admission), resided outside of Ontario, or resided in an NH with 25 or fewer beds, as these smaller institutions are often not designated as standalone facilities and their operations often differ.
For residents who were admitted to an NH more than once, we used the first assessment only to avoid correlated data among residents. This study focused on the admission assessment and a 92-day follow-up period because the risk of an ED transfer is higher for newly admitted NH residents.
The primary outcome was a potentially preventable transfer from the NH to the ED, identified by an ED diagnosis of an ambulatory care sensitive condition, within 92 days of NH admission. The definition for PPEDs has been validated for the NH population and is based on the International Classification of Diseases, 10th Revision (ICD-10) codes for conditions that could appropriately be managed in primary care, such as asthma, chronic obstructive pulmonary disease, congestive heart failure, dehydration, pneumonia, kidney or urinary tract infection, hypoglycemia, diabetes, gastroenteritis, and a severe ear, nose, or throat infection (Supplementary Table 1).
Any visit in which the primary diagnosis is one of these conditions is considered a PPED. This definition was originally defined for the general population but has since been validated for the NH population.
We selected the time to the first ED transfer with 92 days, with residents censored at time of death or discharge from the NH. Non-PPEDs were classified as an ED transfer due to reasons other than those conditions previously mentioned.
Selection of candidate resident characteristics was conducted using clinical expertise and prior literature. These characteristics include demographic, clinical, and social characteristics reported at admission to the NH facility expected to be associated with PPEDs. The methods used for variable selection and the resident characteristics included in the study are described in our previous work.
Descriptive statistics were reported using measures of frequency and central tendency, to compare residents who experienced PPEDs and non-PPEDs. Both theoretical and statistical frameworks were used for model building, as described in our previous work.
We plotted the Cumulative Incidence Function for each outcome. Cox regression was used to provide adjusted associations between resident characteristics and time to PPEDs and non-PPEDs within 92 days as hazard ratios (HR) with 95% CIs. Harrell's C-Statistic was used to determine model discriminability. Data were screened for the presence and pattern of missing data; no missing data were present. Data were managed and analyzed using SAS version 9.4 (SAS Institute).
Secure access to these data is governed by policies and procedures that are approved by the Information and Privacy Commissioner of Ontario. This study was approved by the Hamilton Integrated Research Ethics Board (HiREB #40906).
A total of 56,433 NH residents were examined during the study period. Approximately 22.7% of residents experienced an ED transfer within 92 days of NH admission. Table 1 displays a compressive list of resident characteristics for those who experienced PPEDs and non-PPEDs. Most residents who experienced either PPEDs or non-PPEDs were female (57.6%; 58.7%), were 65+ (93.7 %; 93.6%), and were taking more than 5 medications (91.6%; 87.5%). Residents who experienced PPEDs were less likely to have a do-not-hospitalize (DNH) directive (16.9%), were hospitalized in the last 30 days before admission (41.5%), and had a congestive heart failure diagnosis (25.8%) compared with a non-PPED (20.8%, 36.8%, and 16.2%, respectively). Of the entire cohort, 3498 residents (6.25%) experienced PPEDs and 9331 (16.8%) experienced non-PPEDs within the first 92 days of admission. Approximately 27.0% of residents transferred to the ED experiences a PPED transfer (Figure 1).
Table 1Characteristics of Ontario Nursing Home Residents Experiencing PPEDs and Non-PPEDs Within 92 Days of Admission
Potentially Preventable ED Transfer (n = 3498)
Non–Potentially Preventable ED Transfer (n = 9331)
Fourteen of 18 resident characteristics examined were significantly associated with both PPEDs and non-PPEDs (Supplementary Tables 2 and 3). The most influential resident characteristics that decreased the risk of PPEDs were the presence of a DNH directive (HR 0.61; CI 0.56–0.67), female sex (HR 0.82; CI 0.76–0.88), and having an Alzheimer's or dementia diagnosis (HR 0.82; CI 0.76–0.88) (Figure 2). The most influential resident characteristics that reduced the risk of non-PPEDs were residents with a DNH directive (HR 0.78; CI 0.74–0.83) and female sex (HR 0.82; CI 0.79–0.86) (Figure 2).
Resident characteristics associated with the greatest increased risk of PPEDs were residents on oxygen therapy (HR 1.88; CI 1.69–2.10), residents with cellulitis (HR 1.76; CI 1.40–2.21), and residents with an indwelling catheter (HR 1.65; CI 1.49–1.83). Resident characteristics associated with a greater risk of non-PPEDs were residents on dialysis (HR 2.05; CI 1.75–2.40) and residents who had visited the ED within the past 90 days (HR 1.54; CI 1.45–1.64).
Resident characteristics associated solely with a greater risk of PPEDs are pneumonia (HR 1.48; CI 1.25–1.70) and oxygen therapy (HR 1.88; CI 1.69–2.10), both indicating potential respiratory distress. Resident characteristics associated solely with a greater risk of non-PPEDs are experiencing a change in mood (HR 1.09; CI 1.01–1.18) and delirium (HR 1.08; CI 1.04–1.13), 2 psychosocial factors. The Harrell's C index was 0.54 for PPEDs and 0.55 for non-PPEDs, indicating poor discriminability for both outcomes.
A large majority of the NH resident admission characteristics that we examined were associated with both PPEDs and non-PPEDs. However, because of the similar resident characteristics in both PPED and non-PPED populations, we were unable to differentiate well between NH residents at high risk of either type of transfer. Pilot quality improvement initiatives have aimed to reduce potentially avoidable hospitalizations and have shown promising results.
Our initial aim was to create a tool to support these efforts by accurately discriminating between those at risk of experiencing PPEDs and non-PPEDs. However, even when using highly informative assessment data on NH resident characteristics, we were unable to do so. This inability to distinguish between PPEDs and non-PPEDs suggests that there is an opportunity to revise the indicator with additional factors to improve specificity.
Fourteen of the 18 factors examined had similar associations with PPEDs and non-PPEDs, with most resident characteristics increasing the risk of both types of transfers. However, some resident characteristics were more strongly associated with one type of transfer compared with the other. Our study concurs with previous work, finding that a DNH directive, female sex, and having a diagnosis of Alzheimer's or other dementia were associated with a decreased risk of both PPEDs and non-PPEDs.
Change in mood and a delirium diagnosis were associated with a decreased risk of PPEDs but interestingly, increased risk for non-PPEDs. This may be that the ED can exacerbate changes in mood or symptoms of delirium so NH facilities are less resistant to transfer residents and focus on primary care management strategies to manage acute changes in resident health.
In comparison, being on oxygen therapy or having a pneumonia diagnosis was associated with increased risk of PPED and had no association with non-PPEDs. Other studies have reported pneumonia being the primary reason for a PPED transfer.
This may be that NH facilities can provide more effective care for pneumonia but may not have resources available at the time of transfer. Overall, resident characteristics were unable to discriminate between PPEDs any more successfully than non-PPEDs.
Our study highlights a limitation in the current definition of PPEDs. We are unable to accurately identify patients at high risk for PPEDs, even using the characteristics and conditions that underlie the PPED definition. A clear understanding of prognostic features is needed to proactively mitigate unwarranted ED transfers in an already frail patient population.
Further, this definition is commonly used to delineate clinical care plans and services offered to residents, which may misallocate scarce resources in a poorly targeted manner. Finally, the PPED definition forms the basis for facility-level performance metrics.
If, as our findings suggest, the current distinction between PPEDs and non-PPEDs is nonspecific, then performance metrics may not actually reflect superior care. Given the PPED definition is derived from the World Health Organization in ICD-10-CA codification, our findings transcend national borders.
The current definition is used for research purposes, which, if lacking specificity, may pose challenges to our understanding of nonurgent ED use in the NH population. Future studies should assess the clinical utility of categorizing ED transfers at acute care facilities for this population and explore a revised definition of PPEDs that more accurately reflects the facility and patient experiences of ED transfers by including factors other than ICD-10 codes.
We were limited to secondary data collected using the RAI-MDS 2.0. Thus, certain resident characteristics that can influence ED transfers but are not recorded in the RAI-MDS 2.0 were not evaluated in this study. Including information on the reason for transfer, transfer patterns from the NH facility, and staffing patterns may assist in creating a comprehensive definition for PPEDs.
In addition, information on ED triage acuity would help provide an interfacility perspective, highlighting whether medical acuity assessment was congruent between both institutions. Including updated information about any changes in resident health or care would allow for the development of a more accurate model and would provide a longitudinal view of the phenomena.
Our study demonstrated that NH residents' characteristics are similarly associated with a transfer to the ED for both potentially preventable and non–potentially preventable conditions. The inability to reasonably determine which residents were at risk of PPEDs compared with non-PPEDs suggests that the current the PPED definition may be operationally challenging for this population and that the PPED indicator could be revised to improve specificity.
This study was supported by ICES, which is funded by an annual grant from the Ontario Ministry of Health (MOH) and the Ministry of Long-Term Care (MLTC). Parts of this material are based on data and information compiled and provided by: MLTC and Canadian Institute for Health Information (CIHI). The analyses, conclusions, opinions, and statements expressed herein are solely those of the authors and do not reflect those of the funding or data sources; no endorsement is intended or should be inferred.
Supplementary Table 1ICD-10-CA Codes for Potentially Preventable ED Visits
I20 I2382 I240 I248 I249
Cases with surgical procedure (CCI procedure: 1, 2, 5)
Cases with surgical procedures (CCI: 1, 2, 5)
Chronic obstructive pulmonary disease
J41–J44 J47 J20 (only when “other diagnosis” of J41–J44, J47 is present) J12–J16, J18 (only when “other diagnosis” of J41–J44, J47 is present)