Impact of continuity of care on mortality and health care costs: a nationwide cohort study in Korea.
OBJECTIVE
Continuity of care is considered a core element of high-quality primary care, but its impact on mortality and health care costs is unclear. We aimed to determine the impact of continuity of care on mortality, costs, and health outcomes in patients with newly diagnosed cardiovascular risk factors.


METHODS
We conducted a cohort study of a 3% nationwide random sample of Korean National Health Insurance enrollees. A total of 47,433 patients who had received new diagnoses of hypertension, diabetes, hypercholesterolemia, or their complications in 2003 or 2004 were included. We determined standard indices of continuity of care-most frequent provider continuity (MFPC), modified, modified continuity index (MMCI), and continuity of care index (COC)-and evaluated their association with study outcomes over 5 years of follow-up. Outcome measures included overall mortality, cardiovascular mortality, incident cardiovascular events, and health care costs.


RESULTS
The multivariable-adjusted hazard ratios (HRs) for all-cause mortality, cardiovascular mortality, incident myocardial infarction, and incident ischemic stroke comparing participants with COC index below the median to those above the median were HR = 1.12 (95% CI, 1.04-1.21), 1.30 (1.13-1.50), 1.57 (1.28-1.95), and 1.44 (1.27-1.63), respectively. Similar findings were obtained for other indices of continuity of care. Lower continuity of care was also associated with increased inpatient and outpatient days and costs.


CONCLUSIONS
Lower indices of continuity of care in patients with newly diagnosed hypertension, diabetes, and hypercholesterolemia were associated with higher all-cause and cardiovascular mortality, cardiovascular events, and health care costs. Health care systems should be designed to support long-term trusting relationships between patients and physicians.
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.).
Dong Wook
DW
Shin
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.).
Juhee
J
Cho
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.).
Hyung Kook
HK
Yang
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.).
Jae Hyun
JH
Park
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.).
Hyejin
H
Lee
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.).
Hyunsu
H
Kim
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.).
Juhwan
J
Oh
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.).
Soohee
S
Hwang
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.) belong@snu.ac.kr.
BeLong
B
Cho
Department of Family Medicine & Health Promotion Center, Seoul National University Hospital, Seoul, Republic of Korea (D.W.S., H.L., H.K., B.C.); Department of Family Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea (D.W.S., H.L., B.C.); JW Lee Center for Global Medicine, College of Medicine, Seoul National University, Republic of Korea (D.W.S.); Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Republic of Korea (J.C.); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C., E.G.); Department of Health, Behavior, and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.C.); Cancer Policy Branch, National Cancer Control Institute, National Cancer Center, Goyang, Republic of Korea (H.K.Y.); Department of Social and Preventive Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea (J.H.P.); Department of Health Policy and Management, College of Medicine, Seoul National University, Seoul, Republic of Korea (J.O., H.K.Y.); Health Insurance Review & Assessment Research Institute, Health Insurance Review and Assessment Service, Seoul, Republic of Korea (S.H.); Department of Medicine and Welch Center for Prevention, Epidemiology, and Clincal Research, Johns Hopkins Medical Institutions, Baltimore, Maryland (E.G.); Area of Cardiovascular Epidemiology and Population Genetics, National Center for Cardiovascular Research (CNIC), Madrid, Spain (E.G.) eguallar@jhsph.edu.
Eliseo
E
Guallar
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000150:complications; D015331:Cohort Studies; D003266:Continuity of Patient Care / Q000706:statistics & numerical data*; D003920:Diabetes Mellitus / Q000453:epidemiology / Q000628:therapy; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D006937:Hypercholesterolemia / Q000453:epidemiology / Q000628:therapy; D006973:Hypertension / Q000453:epidemiology / Q000628:therapy; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000191:economics / Q000453:epidemiology* / Q000401:mortality; D010817:Physician-Patient Relations; D011320:Primary Health Care / Q000706:statistics & numerical data*; D056910:Republic of Korea / Q000453:epidemiology; D020521:Stroke / Q000191:economics / Q000453:epidemiology* / Q000401:mortality; D055815:Young Adult
cardiovascular diseases; continuity of care; health care costs; mortality