Evaluation of Geographic Indices Describing Health Care Utilization.
OBJECTIVE
The accurate measurement of geographic patterns of health care utilization is a prerequisite for the study of geographic variations in health care utilization. While several measures have been developed to measure how accurately geographic units reflect the health care utilization patterns of residents, they have been only applied to hospitalization and need further evaluation. This study aimed to evaluate geographic indices describing health care utilization.


METHODS
We measured the utilization rate and four health care utilization indices (localization index, outflow index, inflow index, and net patient flow) for eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee replacement surgery, caesarean sections, hysterectomy, computed tomography scans, and magnetic resonance imaging scans) according to three levels of geographic units in Korea. Data were obtained from the National Health Insurance database in Korea. We evaluated the associations among the health care utilization indices and the utilization rates.


RESULTS
In higher-level geographic units, the localization index tended to be high, while the inflow index and outflow index were lower. The indices showed different patterns depending on the procedure. A strong negative correlation between the localization index and the outflow index was observed for all procedures. Net patient flow showed a moderate positive correlation with the localization index and the inflow index.


CONCLUSIONS
Health care utilization indices can be used as a proxy to describe the utilization pattern of a procedure in a geographic unit.
Department of Health Policy and Management, Seoul National University College of Medicine, Seoul, Korea.
Agnus M
AM
Kim
Department of Health Policy and Management, Seoul National University College of Medicine, Seoul, Korea.
Jong Heon
JH
Park
Department of Health Policy and Management, Seoul National University College of Medicine, Seoul, Korea.
Sungchan
S
Kang
Department of Health Policy and Management, Seoul National University College of Medicine, Seoul, Korea.
Yoon
Y
Kim
D015906:Angioplasty, Balloon, Coronary; D019645:Arthroplasty, Replacement, Knee; D002585:Cesarean Section; D001026:Coronary Artery Bypass; D016208:Databases, Factual; D006620:Hip Fractures / Q000601:surgery; D006801:Humans; D007044:Hysterectomy; D008279:Magnetic Resonance Imaging; D009313:National Health Programs; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data*; D056910:Republic of Korea; D014057:Tomography, X-Ray Computed
 Health care;  Insurance;  Korea;  Utilization;  Variation; Small-area analysis