Background
A patient is defined as having multiple chronic conditions if he or she has two or more chronic conditions [
1], which is a manifestation of multi-comorbidity [
2,
3]. As aging is accompanied by an increasing prevalence of chronic diseases, the disease pattern of the population in developed and developing countries is shifting from infectious diseases, the highest proportion in the past, to chronic diseases which target an aging population. The increase in the number of elderly people, coupled with the evolution of diseases, has led to a steady increase in the incidence of multiple chronic conditions [
4,
5]. Chronic patients have, therefore, become the major users of health care systems. In view of this problem, the coordination and integration of care for patients with multiple chronic conditions not only presents a challenge to the health care system [
6,
7], but has also become an important issue in health policies around the world in the 21st century [
8,
9]. Compared with patients with a single chronic condition, multi-chronic patients deteriorate faster. They also develop disabilities easily due to medical negligence, such as, drug-drug interaction [
1]. Hence, multi-chronic patients require the integration of specialties and continuity of care (COC). This may prevent unnecessary medical services such as repeated medications and examinations, avoid treatment interactions, and obtain a better quality of care [
10]. Especially in a modern health care system, which emphasizes the division of professions among specialty carers, the coordination and integration of patient-centered care has become even more important [
1‐
3].
Continuity of care (COC), which has been commonly accepted as a critical factor in enhancing the quality of care for chronic patients, is widely regarded as the basis of primary care and is defined as a form of seamless and connected care provided according to a patient’s needs [
11‐
13]. COC is defined as a health care service that extends over a period of time, during which there is effective and timely exchange of health information between individual medical professionals or within a medical team. COC provides medical facilities with a better understanding of the patient’s medical history. It can strengthen the physician-patient relationship during the course of care and contribute to more effective case management, as well as develop a long-term case monitoring mechanism [
13]. Thus, COC is generally regarded to encompass three aspects: (1) Information continuity, i.e. continuity of all previous treatment and care-related medical records; (2) Management continuity, i.e. continuous management of the status of diseases; and (3) Relational continuity, i.e. continuity in the relationship between patients and a single or multi-care provider [
14‐
16]. Previous studies have mainly focused on the relationship between COC and care outcomes, such as the satisfaction of physician-patient relationship, case management and the impact that compliance with doctors’ orders produces on care [
17,
18].
Some studies have proposed the concept of fixed COC, such as receiving COC from particular physicians [
19] or medical facilities [
20]. By effectively transmitting medical information, fixed COC can strengthen case management and maintain an effective patient-physician relationship, thereby improving the outcome of medical care [
8,
20]. Mainous and Gill (1998) discussed the influence of COC on admission rates at different medical facility levels. It was found the physician and medical site (facility) levels produced different results [
21]. For multiple chronic conditions, patients need more integrated care from different specialties or a medical team, especially in modern medical systems where there is clear division of specialties. Hence, the study highlights the significance of medical facility levels in COC, which is a particularly important issue when considering the care of multi-chronic patients.
For practical applications, most studies have focused on a single chronic condition and its care outcomes, such as diabetes, asthma and chronic obstructive pulmonary disease [
22‐
26], but few have focused on patients with multiple chronic conditions [
1]. However, the status of care for a single chronic condition often leads to other complications (such as diabetes, which often triggers cardiovascular and kidney diseases), so a common medical behavior is to set one chronic condition as the major condition for treatment [
1]. Thus, for multi-chronic patients, COC goes beyond the scope of a major chronic condition; it should also consider all chronic conditions (multi-comorbidity) and their care outcomes.
Previous research has demonstrated that a higher COC results in better care outcomes [
12,
13], such as reducing the frequency of emergency department (ED) visits and hospitalization, while offering better preventative care [
18,
26,
27], better control of chronic diseases [
22], and higher patient satisfaction [
20,
28]. COC emphasizes the process of care, but data collection is difficult [
24,
29]. While some qualitative studies used a theoretical model, they still lacked empirical evidence [
29]. Different indices have been constructed for COC: some emphasize the duration of the patient-physician relationship; some emphasize the frequencies or sequences of physician care, and some focus on physician numbers. Jee and Cabana (2006) conducted a systematic review on COC indices and presented their advantages and disadvantages, but the study does not point out which index is superior [
30]. For example, the algorithm for Usual Provider Care (UPC) focuses on the number of physicians visited or the visit ratio of the most frequently visited physicians. But UPC cannot detect whether patients reduce their visits or change physicians frequently [
31]. The Continuity of Care Index (COCI) calculates both the total visiting numbers and the number of caregivers, but the calculation is complex [
22]. Sequential Continuity of Care (SECOC) can calculate the sequences of change in medical care, but it may not be suitable for non-sequential issues. Previous research has emphasized that there is no consistent and standardized integrated index for COC [
29,
30], and an individual index cannot present every aspect of COC assessments [
24,
32‐
34]. Furthermore, few indices can explain the relationship between the caregivers and care types. Jee and Cabana (2006) have suggested integrating different types of indices into an integrated index or constructing an index with indices of different weights, in order to assess the COC related to different types of medical care [
30].
In 1995, Taiwan implemented the National Health Insurance (NHI) system, which provides near-universal coverage, with more than 92% of medical care institutions in Taiwan providing NHI medical services [
35,
36]. Like many Asian and European countries, the health care system in Taiwan lacks family physicians and an effective referral mechanism. The general public can freely select a medical site (e.g., clinic or hospital), regardless of the severity of the disease [
17,
26]. The different types of medical services affect the way the public seek medical treatment, which is considerably different from the situation in Europe and America. Western countries that promote integrated care mainly operate under a health care system with family physicians and referral mechanisms. The family physician is the first stop for the public. The physician diagnoses the patient and provides suitable treatment; and if necessary, the patient is referred to a specialist hospital or a large hospital [
37]. By contrast, all hospitals in Taiwan, whatever the size and scale, have a comprehensive care service with different specialist physicians and provide primary care services, as well as outpatient and inpatient services for emergency and critical care [
27]. Due to the accessibility to medical care in Taiwan, the National Health Research Institutes (NHIR) can easily collect longitudinal data of care outcomes and case management of chronic patients at both medical facility and physician levels.
Because Taiwan’s health insurance system has a high coverage and there is ease of access to medical care, Taiwan provides an ideal environment for empirical study on COC. This study aims at constructing an integrated COC (ICOC) index, and verifying the association between ICOC and care outcomes for different scopes of chronic conditions (all chronic conditions and major chronic condition) at physician level and medical facility level.
Discussion
Continuity of care is widely believed to be essential for high-quality patient care. Most COC measurements have focused on a single chronic condition [
3,
11,
12,
22,
51]. In a study of care at different medical sites, Mainous and Gill (1998) found that a high physician continuity of care is better than high facility / low physician or low facility / low physician [
21]. In this study we investigated different scopes of chronic diseases, including all chronic conditions and major chronic conditions, and found different care outcomes at physician and medical facility levels. Patients with a major chronic condition received treatment that resulted in good care outcomes at both physician and medical facility levels. For all chronic conditions the care received at medical facility level resulted in good outcomes, but not so at physician level, where outcomes were poor. In other words, for major chronic conditions with the highest numbers of outpatient visits, the higher the continuity of care, the lower utilization rate of ED services and hospitalization, and thus medical resource utilization will be much lower. Medical service providers should establish disease tracking management plans and provide COC services such as patient-centered long-term case management and maintenance of patient-care provider relationship for loyal chronic patients.
This study differs from previous studies in that it used an empirical approach in the study of multi-chronic patients. In doing so we discovered that for multi-chronic patients, all chronic conditions concentrated at medical facility to received care services will lead to a good outcome. By contrast, all chronic conditions concentrated at physician level to received care services may lead to poor outcomes. As chronic diseases are often accompanied by multi-comorbidity, the need for medical care cannot be entirely met only at physician level. This confirmed our view that because multi-chronic conditions require the care of multiple specialties, the needs of multi-chronic patients are difficult to meet at the individual physician level [
1,
3]. Thus, multi-chronic patients may benefit from a better care outcome if the COC of chronic conditions can take place at integrated facilities or specialties where there is integration of resources and multi-specialities. Because of the increasing need for coordinated care for such patients, different specialists and medical facilities should become integrated in order to enhance the efficiency and efficacy of care, as evidence has shown this to be of benefit [
15,
24]. Medical service providers need to adjust treatment models and intra or inter-organizational integration or establish a referral mechanism for the collaboration of multiple specialties to enhance the accessibility to multi-specialty services. Several studies have suggested that by doing so, health care outcome can be improved [
8,
37]. Instead of single-physician care, a patient-centred, multi-specialty-oriented health care structure for multi-chronic patient is very much needed.
Several studies on COC indices have focused on a single index measurement, which can not be applied to all types of medical care [
3,
30,
33]. This study validated the conclusion of previous studies that different patterns of COC may lead to different results, hence the need for the integration of COC indices [
27,
30]. As ICOC was found to have a better model fitting, we used the respective findings as the basis to put forth our views. This study developed an integrated COC (ICOC) index to evaluate the outcomes of COC for multi-chronic patients. The benefits of this approach are as follows. First, the ICOC index integrated UPC, COCI, and SECOC, thus overcoming the limitations of a single index for different types of medical care. Second, ICOC can replace the individual COC index in interpreting a single condition. Its better model-fitting characteristics also implies that the ICOC index can avoid the bias often encountered in a single index. Third, the ICOC index can be widely applied to the evaluation of different chronic conditions or different types of research. It offers a reliable assessment of different levels of medical care and scopes of chronic conditions; it can also serve as an indicator in multilevel research.
For the measurement of COC and different levels of integrated care for multi-chronic patients, this study presents a preliminary integration of COC measurements and the investigation is limited to the association between COC and care outcomes. In short, the ICOC calculation is a new measurement method, which needs to accumulate more empirical research to establish a standardized measuring method. In the future, it can be widely applied to the evaluation of different chronic conditions or different types of research to verify the care outcome of diseases. In addition, future studies can consider an in-depth analysis of COC in relation to different scopes of medical care, such as by using the dose–response relationship or cut point analysis to find areas of improvement for COC. The findings may be beneficial to decision-makers in enhancing medical-seeking behavior and hospital integration outcomes.
This study does, however, certain limitations. First, although the medical system in Taiwan provides a superior environment for the evaluation of integrated health care, information regarding the degree of actual implementation and integration at individual medical facilities is unavailable. Second, some demographic characteristics and needs, which were not included in the variables, may affect the estimation of the COC outcomes. Third, even though most hospitals in Taiwan have trained staff handling the classification and coding of diseases, mistakes may still remain in the disease codes for the claims data used in this study. We consider this issue a systematic bias. Finally, it should be noted that there may be a correlation problem for the four aspects of COC measurements when using the same index. This is particularly true in the measurement of physician and medical site levels for the same chronic condition scope, as there may be a collinearity problem in constructing a linear model. In other words, when measuring a single disease, the COC measurement at physician level may be the same as that at medical site level. The method proposed in this study is thus not suitable for measuring the same disease. However, this study considers situations where there is a clear division of profession among specialties, and focuses on multi-chronic patients, so the correlation issue is almost negligible (we observed a low correlation in the data). In addition, as people in Taiwan are free to choose their medical facility and physicians, the proposed method may not apply to countries in which a referral system is the foundation of the medical system.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
CLC conceptualized the study, participated in the analysis of the data, drafted the manuscript and revised the manuscript. HTH conceptualized the study and participated in the study design, statistical analysis, and interpretation of data. HJY conceptualized the project, participated in the study design, interpretation of data, writing of the manuscript, and revised the manuscript. HWT integrated the results of the research into clinical problems and revised the manuscript. All authors have read and approved the final version of the manuscript.