INTRODUCTION

Strengthening primary care and acute care is a high-priority policy goal to ensure better health outcomes and lower costs amid rapidly rising medical expenditures in healthcare systems globally [1,2]. To achieve these goals, measuring the quality of care has been emphasized worldwide over the past several decades [3].

Different countries measure the quality of care provided in their healthcare systems using various quality indicators, but avoidable hospitalization rates (AHRs) for chronic ambulatory care-sensitive conditions (ACSCs) and case-fatality rates (CFRs) for acute myocardial infarction (AMI) and stroke are widely used as performance indicators [4,5]. ACSCs such as diabetes and chronic obstructive pulmonary disease (COPD) are diseases for which accessible and effective primary care can reduce the risk of complications and preventive hospitalizations. NHS Digital, the Centers for Medicare and Medicaid Services, and the Agency for Healthcare Research and Quality [6-8] have measured AHRs to provide stakeholders with information that enables them to identify policy interventions to improve the quality of primary care. The CFRs for AMI and stroke reflect the quality of acute care provided, such as whether effective medical interventions were employed and if the patient was transported rapidly enough [3]. Moreover, the Organization for Economic Cooperation and Development (OECD) regularly collects AHRs and CFRs to compare the performance of healthcare systems among OECD member countries.

Measuring the quality of care may provide stakeholders with important evidence for policy development and decision-making [1]. Nevertheless, little is known about the quality of primary care and acute care provided in Korea. This study aimed to examine trends in the quality of primary care and acute care provided in Korea and explore factors that have contributed to changes using a population-based nationwide database.

METHODS

This population-based, cross-sectional study used data from the National Health Insurance Claims Database (NHICD) collected by the Health Insurance Review & Assessment Service (HIRA). Admission data for the period 2008 to 2020 were extracted from the NHICD, which contained patients’ medical records, including the diagnosis, medication prescribed, and examination notes [9]. The occurrence of death within 30 days of admission of patients who were diagnosed with AMI or stroke was obtained by linking the NHICD to the Resident Registration System of the Ministry of the Interior and Safety.

Variables and Measures

CFRs and AHRs were used to investigate the quality of primary care and acute care, respectively. There is no consensus on which conditions should be included in the list of ACSCs [10]. This study included AHRs for asthma, COPD, congestive heart failure (CHF), hypertension, and diabetes, which were collected by the OECD, to compare them with other countries. The AHR was defined as the number of hospital admissions with a principal diagnosis of certain diseases among people aged 15 years and older per 100 000 people. International Classification of Disease, 10th revision (ICD-10) codes for the diseases that we included in our study are as follows: asthma (J45.x, J46.x), COPD (J40, J41.x, J42, J43.x, J44.x), CHF (I11.0, I13.0, I13.2, I50.0, I50.1, I50.9), hypertension (I10.x, I11.9, I12.9, I13.9), and diabetes (E10.x, E11.x, E13.x, E14.x). Admissions resulting from the transfer of a patient from another hospital and where the patient died during the admission process were excluded from the study sample, as these deaths were considered to be unavoidable [11]. Data regarding the number of the general population were obtained from the National Statistical Office of Korea and utilized as the denominator for the AHR.

AMI and stroke are representative of diseases requiring acute care within the “golden hour” [12]. We included CFRs for AMI and stroke, which were also collected by the OECD. The CFR is defined as the percentage of patients aged 45 years and older who die within 30 days following admission with a primary diagnosis of AMI (ICD-10: I21.x, I22.x) and stroke (ICD-10: I60.x-I62.x for hemorrhagic stroke, I63.x and I64.x for ischemic stroke).

Statistical Analysis

The CFRs and AHRs were calculated for the period from 2008 to 2020, and then standardized by age and sex to adjust for patients’ characteristics over time. Age-/sex-standardized CFRs and AHRs were estimated using the direct method with reference to the 2010 OECD population aged 45 years and older admitted to hospitals for AMI or stroke, and the 2010 OECD population aged 15 years and older, respectively [11]. Changes in age-/sex-standardized CFRs and AHRs were quantified by joinpoint regression, which was utilized to find the inflection points. In years in which trend changes occurred, the annual percent change (APC), the average annual percent change (AAPC), and their 95% confidence intervals (CIs) were estimated. The slopes were categorized as increasing or decreasing if the estimated slope differed significantly from 0 [13].

For statistical analysis, SAS Enterprise Guide 7.1. (SAS Institute Inc., Cary, NC, USA) and Joinpoint regression version 4.9.0.1 (National Cancer Institute, Bethesda, MD, USA) were used. A p-value <0.05 was considered statistically significant.

Ethics Statement

This study was approved by the Institutional Review Board of the HIRA (No. 2023-038-001).

RESULTS

Changes in Case-fatality Rates for Acute Myocardial Infarction and Stroke

As shown in Table 1, the age-/sex-standardized CFRs for AMI and stroke decreased significantly between 2008 and 2020. The CFR for AMI in 2008 was 14.2%, while in 2020 it was 10.6%. The AAPC was -2.3% (95% CI, -4.6 to 0.0) with borderline significance (Table 2). Joinpoints were detected in 2013 and 2017. The APC between 2013 and 2017 increased, but this increase was not statistically significant (p=0.154).

With regard to hemorrhagic stroke, the age-/sex-standardized CFR was 21.8% in 2020 and decreased steadily since 2008 (27.1%), with an AAPC of -1.8% (95% CI, -2.7 to -0.9). We found that the downward trend between 2011 and 2015 was significantly greater than in other periods. Our results indicate that the age-/sex-standardized CFR for ischemic stroke decreased overall, without any inflection points, and the AAPC was -3.5% (95% CI, -4.0 to -3.1).

Changes in Avoidable Hospitalization Rates

The age-/sex-standardized AHRs for all diseases decreased considerably between 2008 and 2020 (Table 1). In 2020, the AHRs for asthma and COPD were 38.5 per 100 000 people and 88.5 per 100 000 people, respectively; the AAPC was -7.8% (95% CI, -10.1 to -5.5) and -7.1% (95% CI, -10.3 to -3.9), respectively (Table 2). Asthma and COPD had the same inflection point, and the APCs for the 2018 to 2020 period (-27.4 and -27.2%, respectively) were larger than those for the 2008 to 2018 period (-3.3 and -2.5%, respectively). Unlike other diseases, the AHR for CHF increased only slightly between 2013 and 2018, and the APC did not show a significant change (0.1%; 95% CI, -0.8 to 0.9; p=0.860). The AHRs for hypertension and diabetes were 56.3 per 100 000 and 191.2 per 100 000 people in 2020, respectively, reflecting decreases of 71.3% and 45.3%, respectively, since 2008 with no inflection point.

DISCUSSION

After 2008, the age-/sex-standardized CFRs for hemorrhagic and ischemic strokes decreased, with AAPCs of -1.8% and -3.5%, respectively. The age-/sex-standardized CFR for AMI increased temporarily between 2013 and 2017, but decreased again after 2017. The age-/sex-standardized AHRs also decreased substantially. In particular, a relatively large decrease was observed in 2020 during the coronavirus disease 2019 (COVID-19) pandemic.

The age-/sex-standardized CFRs for AMI, and hemorrhagic and ischemic strokes decreased between 2008 and 2020. The decrease in CFRs observed in this study is in line with previous trends in other countries [14-16]. The health outcomes of AMI and stroke patients are determined not only by rapid and effective medical interventions in the hospital, but also by interventions outside the hospital, such as the management of risk factors for cardio/cerebrovascular disease, emergency responses, and timely transport of patients. Many countries, including Korea, have implemented a variety of interventions to improve health outcomes, which have resulted in a decrease in mortality [3]. Lecoffre et al. [17] reported that France established a national strategy for the management of stroke patients, including the establishment of stroke units in hospitals in 2000, and as a result, in-hospital mortality decreased by 17.1% in patients with ischemic stroke. In Korea, the decrease in CFRs for AMI and stroke can be explained by improvements in therapeutic technologies and effective interventions implemented by clinical societies and the Ministry of Health and Welfare (MOHW). The Korean Society of Cardiology has implemented a cardiovascular intervention institute/specialist certification system [18], and the Korean Stroke Society strongly recommended the establishment of stroke units within hospitals [19]. Nationwide programs have been implemented by national institutions commissioned by the MOHW. The HIRA conducted the National Quality Assessment Program (NQAP) [20] and the National Medical Center evaluated emergency medical services institutions [21]. In addition, regional cardio/cerebrovascular centers were designated to provide comprehensive condition management [22].

Compared with OECD countries based on the 2019 data, the age-/sex-standardized CFR of 11.0% for AMI was higher than the OECD average of 8.8%, while the CFR for stroke was lower than the OECD average, showing contradictory results [23]. This can be explained by considering in-hospital and out-of-hospital factors [1]. With regard to in-hospital factors, the quality of in-hospital care has improved in terms of a decrease in CFRs for AMI and stroke over the past decade. The HIRA reported that the rates of brain scan and thrombolysis therapy initiated within 60 minutes of hospital arrival for ischemic stroke in 2018 were 99.1% and 94.9%, respectively, a significant increase compared with the 2008 rates (83.5 and 47.6%, respectively) [20]. In 2018, the number of emergency institutions that met the criteria, including health employment and physical and technical resources, was 91.0%, a substantial increase compared with the 2009 figures (40.0%) [21]. Regarding out-of-hospital factors, the following explanations can be given: first, the awareness of AMI and stroke symptoms in 2020 was low (50.6 and 57.5%, respectively) [24]. However, the awareness of the early symptoms of stroke was higher than that of AMI because the incidence of stroke in Korea is twice as high as that in Western countries. Because patients in Korea visit the hospital immediately after experiencing symptoms, there are many patients who are treated with mild symptoms, such as transient ischemic attacks. Second, the median time between symptom onset and hospital arrival for AMI gradually decreased from 156 minutes in 2008 to 140 minutes in 2012; however, this time was still longer than the recommended median time [18]. This means that patients present to hospitals long after the onset of symptoms and let the disease progress too long before seeking treatment. We suggest that promoting awareness and education about the symptoms of AMI and stroke is needed to improve patients’ health outcomes. Lastly, a large portion of the incidence of AMI and stroke was explained by major modifiable risk factors such as high blood pressure and diabetes. Kim et al. [18] reported that the prevalence of hypertension, diabetes, and dyslipidemia increased in AMI patients; therefore, it is possible that the patients’ condition was already serious upon arrival at the hospital. In contrast, acute stroke events have become less frequent as a result of a decline in risk factors [21,25].

The AHRs showed an overall decline in the period studied, and the decrease was even greater in 2020 because of the COVID-19 pandemic. This downward trend was also reported in other countries [3]. In the United States, the AHRs for ACSC in 2014 were 1426 per 100 000 people, and this rate has been decreasing since 2005 [26]. In Korea, national programs such as the NQAP for chronic diseases [20], the Chronic Disease Care System program [27], the Korean Community-based Noncommunicable Disease Prevention and Control program [28], and the Pilot Project for Primary Care Chronic Disease Management [29] have been implemented to encourage the public to manage chronic diseases. According to the NQAP report on chronic diseases, the medication adherence rate in 2019 was 91.9% for both hypertension and diabetes, reflecting slight increases since 2011, when the rates were 88.9% and 88.0%, respectively [20]. In addition, the rates of treatment for patients with hypertension and diabetes improved substantially from 2005 to the period between 2016 to 2018 (hypertension: from 49.6 to 65.3%, diabetes: from 49.0 to 66.2%) [30].

Our results indicated that the AHRs of diabetes, asthma, and hypertension, but not COPD and CHF, were higher than that of OECD countries based on the 2019 data [23]. The age-/sex-standardized AHRs for asthma and diabetes were 65 per 100 000 people and 224.7 per 100 000 people, respectively, which were twice as high as the OECD averages (34.2 per 100 000 people and 116.2 per 100 000 people, respectively). Although the AHRs for COPD and CHF were lower than the OECD averages, the AHR for CHF (88.5 per 100 000 people) was about one-third of the OECD average of 213.6 per 100 000 people. The AHR for hypertension was 74.1 per 100 000 people, which was comparable to the OECD average of 73 per 100 000 people.

Previous studies have reported that high AHRs could be explained primarily by the healthcare delivery system, healthcare resources, and prevalence and severity of diseases [5,31]. Nevertheless, Korea’s high AHRs may be caused by structural problems, including aspects of the healthcare delivery system and healthcare resources, such as the number of hospital beds. Although there are some limitations in comparing the prevalence of hypertension and diabetes because of different data sources and population age, the prevalence in Korea is not high compared with other countries [32,33]. Unfortunately, studies that compare the severity of these diseases among countries were not found. We suggest that the results of our study could possibly be explained by the nature of Korea’s healthcare system, in that Korea has achieved universal health coverage with a private-oriented healthcare provider system in a short period of time. Similarly, the OECD reported that primary care in Korea’s healthcare delivery system is not yet wellestablished, which is a major reason for the high AHRs compared with other OECD countries. The number of hospital beds available is one of the factors contributing to AHRs. Kim et al. [31] reported that a larger number of hospital beds was associated with increased AHRs for ACSCs in Korea.

This study was not without limitations. First, an examination of the CFRs and AHRs alone is not sufficient for a comprehensive investigation of the quality of acute care and primary care being provided. However, these have been found to be indirect indicators representing the level of the quality of emergency care provided and the care level involved in the management of patients with chronic diseases, respectively. In addition, many countries have used these indicators to assess the quality of care [34]. Second, patients admitted to hospital with the specified diseases were extracted from the NHICD based on the primary diagnosis. As the information in the NHICD is collected for payments of medical expenses, there may be scope for inaccuracies. However, the accuracy of diagnoses was higher for the diseases included in this study than for other diseases [35]. Third, the CFR and AHR in 2020 should be interpreted in the context of the COVID-19 pandemic. The CFRs for AMI and stroke in 2020 did not significantly increase compared to 2019, whereas the AHRs decreased considerably. These changes may reflect restrictions in access to health care resulting from hospital closures, rather than the quality of care provided during the pandemic. Lastly, factors affecting the indicators, including the severity of diseases and the age of the study population, were not clearly presented. Further exploratory studies are needed to investigate factors contributing to changes in the quality indicators.

The AHRs and CFRs, which are widely used performance indicators for primary care and acute care, respectively, have decreased overall over the past decade in Korea. Nevertheless, there are still further challenges to improving patients’ health outcomes, including efforts to raise awareness of the causes and signs of AMI and how to manage modifiable risk factors. The development of a functional and effective primary care system is the main priority for strengthening the quality of care in the rapidly aging Korean population.

Notes

CONFLICT OF INTEREST

The authors have no conflicts of interest associated with the material presented in this paper.

FUNDING

None.

AUTHOR CONTRIBUTIONS

Conceptualization: Han SJ, Kim KH. Data curation: Gwon YG, Han SJ. Formal analysis: Han SJ, Gwon YG. Funding acquisition: None. Methodology: Kim KH. Project administration: Kim KH, Gwon YG. Writing – original draft: Gwon YG, Kim KH. Writing – review & editing: Han SJ.

ACKNOWLEDGEMENTS

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Figure & Data

References

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