Journal List > J Korean Acad Oral Health > v.39(1) > 1057676

Ahn, Kim, and Shin: Horizontal inequities in dental service utilization

Abstract

Objectives

Health inequity across social classes is closely associated with unequal healthcare utilization, and there have been sustained efforts to improve healthcare accessibility. Public healthcare insurance is one attempt to eliminate such health inequities. The purpose of this study was to examine a horizontal equity index for dental service utilization, which included diverse factors affecting health inequity, such as personal health and social context variables.

Methods

The 2008 to 2011 outpatient datasets of the Korean Healthcare Panel were analyzed. Zero-inflated negative binomial regression (ZINB) was conducted to estimate need-adjusted healthcare use with the following independent variables: health outcome (EQ-5D), chronic disease, and the Composite Deprivation Index. The concentration index and horizontal inequality index were calculated for the actual use of dental services and resource use-based dental visits.

Results

The ZINB regression analysis showed that age and personal health level on the EQ-5D were significant predictors, and the Composite Deprivation Index was influential. The concentration index for dental service utilization indicated that there was inequity favoring high-income brackets, but there was inequity favoring low-income groups when health level was taken into account. Overall, the horizontal equity index for dental service utilization estimated based on the two values was positive, meaning that there was inequity favoring high-income groups.

Conclusions

The use of dental services has been steadily on the rise, and dental service accessibility and public healthcare coverage seem to have expanded. However, when the horizontal equity index for dental service utilization was estimated based on health level, there was inequity, with high-income groups making more use of dental services. Thus, equal access to dental services is not guaranteed, despite the adjustment for need. Methods of increasing dental service use in different income brackets must be carefully considered to remove disparities in the use of dental services.

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Fig. 1.
Concentration curve of healthcare utilization.
jkaoh-39-9f1.tif
Fig. 2.
Income related to dental utilization.
jkaoh-39-9f2.tif
Fig. 3.
Concentration curve of actual and predicted dental visits.
jkaoh-39-9f3.tif
Table 1.
Composition of Korea Health Panel data
Total Outpatient visit Dental visit
Household Persons Household Persons Household Persons
2008 7,009 21,283 6,815 16,907 2,734 3,803
2009 6,134 19,153 6,185 15,715 2,678 3,804
2010 5,956 17,855 5,859 14,928 2,588 3,689
2011 5,741 17,035 5,629 14,194 2,587 3,737
Table 2.
Variables of using analysis
Variables name Description
Dependent variables Dental visits Number of dental visits
Adjusted dental visits Resource use adjusted dental visits
Independent variables Composite deprivation index Deprivation index of district level community
Gender 1=male, 2=female
Age 1=20-44 years, 2=19 years or below, 3=45-64 years, 4=65 years or over
Chronic diseases related in oral health 1=no, 2=yes
EQ-5D Valuated health status
Table 3.
Demographic characteristics of respondents (unit: persons, %)
Frequency %
Gender Male 26,080 45.08
Female 31,776 54.92
Age 19 years or below 16,148 27.91
20-44 years 15,293 26.43
45-64 years 15,908 27.50
65 years or over 10,507 18.16
Education level Middle school or lower 28,681 49.57
High school 15,431 26.67
College or higher 13,744 23.76
Income quartile Low 14,400 25.00
Low-middle 14,416 25.03
High-middle 14,462 25.11
High 14,316 24.86
Marital status Unmarried 20,164 34.86
Married 32,112 55.52
Divorced/separated/widowed 5,560 9.61
Private insurance Uninsured 17,563 30.29
Fixed benefit insured 34,310 59.17
Indemnity insured 6,115 10.55
Table 4.
ZINB regression analysis of the number of visits & adjusted co-payments visits in dental
2008-2011 pooled’ 2008 Resource 2009 Resource 2010 Resource 2011 Resource
Number of dentalvisits Resource use based use based dentalvisits use based dentalvisits use based dentalvisits use based dentalvisits
e^b* P>z e^b* P>z e^b* P>z e^b* P>z e^b* P>z e^b* P>z
Number
Composite de- Middle 1.0388 0.3020 1.0201 0.4580 1.0860 0.1430 1.0107 0.8350 0.9845 0.7730 1.0040 0.9400
privation index
High 0.9545 0.2020 0.9430 0.0260 1.0106 0.8460 1.0033 0.9470 0.8305 0.0000 0.9530 0.3640
Gender Female 1.0613 0.0550 1.0587 0.0110 1.0679 0.1560 1.1482 0.0010 1.0659 0.1570 0.9817 0.6760
Age 19 years or below 1.1972 0.0370 1.1451 0.0310 0.9997 0.9980 1.0557 0.6150 1.3526 0.0230 1.3243 0.0690
45-64 years 1.3032 0.0000 1.2217 0.0000 1.2531 0.0000 1.2482 0.0000 1.2033 0.0000 1.1858 0.0010
65 years or over 1.3867 0.0000 1.2544 0.0000 1.3799 0.0000 1.1716 0.0100 1.2563 0.0000 1.2100 0.0020
Chronic disease Yes 0.9230 0.1040 0.9516 0.1660 0.9206 0.3240 0.8931 0.1310 0.8420 0.0110 1.0693 0.3040
EQ-5D weight 1.2644 0.1600 1.3958 0.0050 1.3366 0.2820 1.1982 0.4330 1.4525 0.1200 1.5298 0.0560
Constant 0.4423 0.0170 3.4683 0.0000 3.3962 0.0000 3.4159 0.0000 3.4750 0.0000 3.6010 0.0000
Inflate
Composite de- Middle 1.1180 0.0080 1.0783 0.0100 1.2044 0.0020 1.1020 0.0920 1.0590 0.3190 0.9751 0.6590
privation index High 1.0444 0.3010 1.0534 0.0710 1.0556 0.3680 1.0533 0.3590 1.0231 0.6870 1.0758 0.2030
Gender Female 1.0008 0.9830 0.9804 0.4110 0.9670 0.5080 0.9892 0.8180 0.9796 0.6650 0.9839 0.7320
Age 19 years or below 0.9322 0.4830 0.8965 0.1110 0.9203 0.5240 0.7719 0.0370 0.9920 0.9540 0.9281 0.6530
45-64 years 0.8189 0.0000 0.7814 0.0000 0.8325 0.0020 0.7647 0.0000 0.7668 0.0000 0.7674 0.0000
65 years or over 1.0181 0.7150 0.9075 0.0050 1.0161 0.8280 0.9334 0.3120 0.8868 0.0800 0.8357 0.0070
Chronic disease Yes 1.4291 0.0000 1.3660 0.0000 1.6126 0.0000 1.4037 0.0000 1.3125 0.0000 1.2979 0.0000
EQ-5D weight 0.5712 0.0020 0.5899 0.0000 0.5383 0.0230 0.5373 0.0160 0.6100 0.0420 0.6734 0.1030
Constant 0.8386 0.0000 1.7198 0.0000 1.8596 0.0000 1.8027 0.0000 1.6866 0.0000 1.5505 0.0000

note: e^b*, exponential (b)=factor change in expected count for unit increase in X or factor change in odds for unit increase in X. reference group-composite deprivation index: low, gender: male, age: 20-44 years, chronic disease: no.

Table 5.
HIwv index in 2008-2011
Number of dental visits Number of dental visits Resource use based
Cm Cn HIwv Cm Cn HIwv
All 0.0567 ―0.0031 0.0597 0.0705 0.0019 0.0686
2008 0.0595 ―0.0062 0.0657 0.0722 ―0.0009 0.0731
2009 0.0614 0.0035 0.0579 0.0777 0.0083 0.0694
2010 0.0474 0.0013 0.0461 0.0633 0.0055 0.0578
2011 0.0368 ―0.0076 0.0445 0.0471 ―0.0016 0.0487
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