Background
In the past few decades, developed countries have faced similar challenges related to the quality and efficacy of care for rapidly aging populations, including an increasing prevalence of chronic illnesses, rising healthcare expenditure, and maldistribution of medical resources. The increasing demand for healthcare services in super-aged society requires overall optimization of effective use of healthcare resources. A reduction in the length of hospital stay (LOS) among patients is one aspect of this strategy. In Japan, which has a super-aged society, the shift from hospital care to community care, including shortening of the LOS, has been promoted as a health policy based on the Community-based Integrated Care System [
1‐
5].
It is important to discharge elderly patients admitted for acute diseases in a condition that allows them to be independent. However, policymakers and physicians were concerned that policies targeting shortening of the LOS and reduction of readmission might have unintended consequences that adversely affect patient care, potentially leading to increased deterioration in the patient’s condition after discharge [
6]. For instance, the financial demerit imposed by the Diagnostic Procedure Combination (DPC)/Per-Diem Payment System (PDPS) may have inadvertently pushed some hospitals to avoid readmissions with the same disease, potentially diverted hospital resources and efforts away from other quality improvement initiatives, or worsened the quality of care at resource-poor hospitals. The DPC/PDPS is a Japanese reimbursement system for acute care hospitals introduced in 2003, and the DPC/PDPS database is a national administrative claims and discharge abstract database for inpatient acute care [
7‐
9].
Cerebral infarction is a common disease among the elderly and is responsible for a decline in ADL, particularly manifesting in the form of motor, somatosensory, language, visual, attention, and memory deficits [
10]. In Japan, there were a total of 76.0 thousand and 51.0 thousand outpatients with cerebral infarction in 2020, and cerebrovascular disease is the second leading cause of disability after dementia in 2019 [
11,
12]. Elderly patients have a high probability of undergoing prolonged hospitalization before discharge; therefore, care during hospitalization, including appropriate discharge management and support, is more important for elderly patients than for younger patients.
Optimal care during hospitalization may reduce worsening of patient outcomes. However, adjustment of patient risks is required to compare and evaluate hospitals with different capacities and functions and ascertain whether each hospital’s care brought standard outcomes. In this regard, risk-adjusted tools or quality indicators, such as the standardized mortality ratio, were used worldwide [
13]. Some of them have also been applied to health policy decisions. Administrative data, such as DPC/PDPS data, are useful for designing health policies for disease management, and for the analysis of healthcare processes and patient outcomes [
14‐
19]. In Japan, acute care hospitals can analyze their own quality of care using DPC/PDPS data. In recent years, risk adjustment methods and quality indicators have been actively researched and utilized in clinical practice such as hospitalization decision or patient flow management [
13,
20,
21].
This study aimed to develop and evaluate the hospital-level risk-adjusted ADL maintenance during hospitalization for elderly patients with cerebral infarction.
Discussion
In this retrospective observational study performed with administrative claims data, the HSAR for cerebral infarction, which was a patient-risk-adjusted indicator with high predictivity, could capture the quality of hospital care. Therefore, we considered the HSAR to be a useful quality indicator to measure the care during acute hospitalization when considering the post-hospitalization life of the elderly. In Japan, the DPC/PDPS is a standard reimbursement system for acute-care hospitals; therefore, the HSAR methods can be widely applied. The results of this study showed that HSAR-based evaluations provide a robust model, and HSAR can be used as a relatively simple tool by hospitals.
Among individual control variables, aging is well known to contribute to the aggravation of cerebral infarction and decline in ADL. The result of chi-square tests and Mann-Whitney U tests for the relationship between changes in ADL and the variables showed significance. After adjusting for patient risk, some hospitals were found to have lower HSAR scores. Since the aim of this study was to identify hospitals that did not meet the standard outcomes for which they should intervene, the HSAR allowed for relative quality assessment and possible improvement on the basis of the case-mix. In this observational study, the confounding variables could not be adjusted; however, the variables used in the regression analysis were considered appropriate. For the risk-adjusted method, we used logistic regression analysis and the case-mix approach as used in previous studies, which were also effective in this study. In the correlation analyses for HSARs, we found that hospitals with high/low HSAR have tend to produce similar results in the following period. Thus, the results suggested that the HSAR for cerebral infarction identified the characteristics of hospital care for ADL maintenance. Notably, we found that hospitals with high/low HSAR were likely to produce the same results in the following period. This result suggested that the HSAR for elderly patients with cerebral infarction was a stable indicator and that the HSAR of the hospitals was influenced by underlying factors. We thought that it is necessary to investigate the characteristics of hospitals with good HSAR so that those with poor HSAR can get beneficial information in improving the ADL care.
Our study included a large sample size to develop risk-adjusted methods for quality indicator. To the best of our knowledge, this is the first large-scale study to calculate the HSAR using DPC/PDPS data. Importantly, the results for the c-statistics showed predictive ability and the HSAR model was highly robust. However, this study had some limitations. First, the hospitals assessed in this study may not be representative of all hospitals in Japan because they voluntarily participated in the benchmarking project. In addition, the information on hospitals was anonymized, so the bed size and function of hospitals could not be used as a variable, and additional discussion of the results was not possible. We plan a validation study using larger-scale DPC/PDPS data in Japan as a future study. Second, other risk factors for deterioration of ADL, such as medical history or socioeconomic status were not considered in this study [
37‐
39]. The risk of requiring rehabilitation during hospitalization and whether rehabilitation was planned at the time of admission should have been accounted [
40]. Third, we could not include the information of discharge destination, which may be a reason for discharging patients in a poor condition, such as those with comorbidities or chronic diseases. This means that if rehabilitation or long-term care is planned at the transfer hospital, the patient might be discharged even if their condition deteriorates after the initial hospitalisation. Other possible adjustment variables such as a Body mass index at admission, but were excluded due to the large number of missing data in the data set used in this study [
41,
42]. We would like to incorporate them in an analysis with larger data set.
The results of this study indicated the need for research on the care system for the maintenance of ADL. To improve care during hospitalization, the findings from a good care system of hospitals with HSAR over 100 should be used to evaluate the care in hospitals with HSAR less than 100, and hospitals and policymakers should evaluate the quality of hospital care management, including rehabilitation [
43]. In a super-aged society, HSAR based on DPC/PDPS data can be considered a useful indicator for hospital managers and policymakers in healthcare. Future studies should aim to analyze the relationships between HSAR and other quality indicators such as mortality or readmission, and consider other adjustment variables such as socioeconomic status that were not in the DPC/PDPS database [
44,
45]. In Japan, the integration of healthcare records and long-term care records is underway, and it is expected that comprehensive care analyses will be possible.
In conclusion, the study of the HSAR as an indicator to support hospital management, including the trends in one's own hospital, may lead to improve the quality of care. In this study, the HSARs for cerebral infarction could be calculated using administrative claims data in Japan. As a new quality indicator, HSARs showed variation among hospitals with comparable case-mixes and might contribute to the development of more useful set of quality indicators for hospitals to improve their quality of care.
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