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Estimating the severity distribution of disease in South Korea using EQ-5D-3L: a cross-sectional study

  • Minsu Ock1,
  • Min-Woo Jo1,
  • Young-hoon Gong2,
  • Hyeon-Jeong Lee1,
  • Jiho Lee3 and
  • Chang Sun Sim3Email author
Contributed equally
BMC Public HealthBMC series – open, inclusive and trusted201616:234

https://doi.org/10.1186/s12889-016-2904-5

Received: 20 November 2015

Accepted: 22 February 2016

Published: 8 March 2016

Abstract

Background

There is a paucity of data on the distribution of disease severity. In this study, we estimated disease severity distributions in South Korea using two EQ-5D-3L population surveys.

Methods

A total of 110 health states for 35 diseases with 2–5 severity levels (e.g., mild, moderate, severe) were included in this study. A general population of 360 participants from the areas surrounding Seoul and Gyunggi evaluated these health states using EQ-5D-3L via face-to-face interviews and a paper questionnaire. The EQ-5D indices were used to measure the severity levels of health states and used as the cutoff points for the disease severity distributions. Finally, these cutoff points were applied to disease prevalence data with EQ-5D-3L, which were obtained from the Korean National Health and Nutrition Examination Surveys (KNHNES) and Korean Community Health Survey, in order to estimate the disease severity distributions.

Results

The severity distributions of 8 diseases were estimated, including asthma, angina, stroke, chronic obstructive pulmonary disease, major depressive disorder, musculoskeletal problems in the legs, anemia, and allergic rhinitis and conjunctivitis. For example, the EQ-5D indices for chronic obstructive pulmonary disease severity were 0.929, 0.742, and 0.620, and the cut-off points were 0.835 (between mild and moderate) and 0.681 (between moderate and severe). Using these cutoff points, the distributions of chronic obstructive pulmonary disease severity were 66.5 % (mild), 23.3 % (moderate), and 10.1 % (severe) according to KNHNES.

Conclusions

The estimated severity distributions in this study can be used as a valid calculation of the disease burden in the general population.

Keywords

Disease severity Prevalence EQ-5D

Background

The disability-adjusted life year (DALY) is a summary measure of overall disease burden and is expressed in terms of the number of years lost due to poor health, disability, or early death [1]. DALY has 2 components: years of life lost (YLLs) and years lived with disability (YLDs). This measure was first developed in 1990 as an approach for comparing the overall health and life expectancies of different countries [2]. Recently, the Global Burden of Disease (GBD) study group adopted a prevalence-based approach rather than an incidence-based approach [3]. Using both approaches, the YLL component is calculated using the same principle, which takes advantage of the number of deaths and standard life expectancy at age of death in years. However, when determining the YLD component, there are some differences between the 2 approaches in terms of disease duration, disability weight, and comorbidity [4]. Using the prevalence-based approach, disease duration is not directly considered and the disability weights are applied to the disease sequelae rather than the disease itself. In addition, it is easier to consider comorbidity using the prevalence-based approach than the incidence-based approach.

Notably, the prevalence-based approach uses big changes related to disability weight. In fact, after the development of DALYs, there have been some debates on the measurement of health loss, the use of person trade-offs, disability weights of whose perspectives, and the universality of disability weights [5]. In their 2010 study, the GBD group conducted international surveys on the general public using paired comparisons to estimate disability weights [6]. These changes make it easier to calculate DALYs, but this approach requires more data that were not needed when using the incidence-based approach, such as data about severity distribution [7]. Using the prevalence-based approach, the GBD group attempted to consider sequelae severity and briefly described the health state and sequelae severity [6]. In order to apply data on severity distributions and calculate DALYs, the GBD group asked a convenient sample of participants to evaluate SF-12v2 [8] for a hypothetical person, who was depicted as living with a certain health state from among 60 possible health states [9]. The GBD group then used population survey data from the United States and Australia to estimate marginal severity distributions.

They adapted this method because data on severity distributions are often scarce. However, applying the data on severity distributions from one country to another would impose limitations due to differences in race, economic factors, and healthcare system accessibility [10, 11]. In South Korea, two population surveys are available, the Korean National Health and Nutrition Examination Surveys (KNHNES) and Korean Community Health Survey (KCHS), which have prevalence data and health-related quality of life (HRQoL) data using EQ-5D-3L [12]. Therefore, disease severity distributions could be determined from the KNHNES and KCHS modifying the method used in the GBD study. In our current study, we estimated disease severity distributions in the Korean general population using two EQ-5D-3L population surveys and health state valuation survey data.

Methods

Study participants

A general population of 360 adults (≥19 years) from the areas surrounding Seoul and Gyunggi participated in this study. The study participants were recruited and stratified according to age, sex, and education using data from the 2010 Census of Korea. The sample size was determined by allocating 30 participants to each health state group (12 health state groups).

Ethical considerations

This survey was conducted by a commercial survey company, who used face-to-face interviews and paper questionnaires after obtaining informed consent. This study was approved by the institutional review board of Asan Medical Center (S2014-1677-0002).

Health state valuation survey procedure and health states

First, sociodemographic characteristics were determined, such as sex, age group, region, and education level. Second, each study participant described their own health states using EQ-5D-3L to adapt to the instrument. Lastly, the study participants were asked to complete EQ-5D-3L for 9 or 10 hypothetical people, as described by the lay descriptions of health states in the order of good health states.

In total, 110 health states of 35 diseases with 2–5 severity levels (e.g. mild, moderate, and severe) were included in this study. Those health states mainly originated from 220 health states, which were described in the 2010 GBD study [6]. Each health state was depicted in terms of the lay descriptions, which described the status of each health state in terms of several health aspects. Because the lay descriptions were originally developed in English, MO first translated these descriptions, which were rechecked by MWJ. In addition, 4 diseases—allergic rhinitis and conjunctivitis, annoyance, sleep disturbance, and cognitive impairment in children—were included in this study, because of local national burden of disease study for environmental diseases. The health states of additional 4 diseases were drafted by 2 authors (MO and MWJ) after referencing the existing lay descriptions reported by a previous study [6]. These 110 health states were divided into 12 groups, which were composed of 9–10 health states. Thirty participants were allocated to each health state group, therefore, each health state had 30 EQ-5D-3L responses. Exceptionally, the 3 health states related to anemia included 2 groups, so each health state of anemia had 60 EQ-5D-3L responses. We considered that at least 30 EQ-5D-3L responses using mean as a representative value would make parametric statistical tests possible. Table 2 lists the diseases and severity levels.

Analysis

Descriptive analyses of the basic characteristics of the study participants were first conducted. Then, the severity distributions were estimated using survey data obtained by this study and prior population survey data. Figure 1 shows the approach for estimating the severity distributions of the health states in this study. The EQ-5D-3L responses from each health state were transformed to the EQ-5D-3L index using the Korean EQ-5D-3L value set [13]. We used EQ-5D-3L rather than SF-12v2 because the KNHNES and KCHS adapted EQ-5D-3L to measure HRQoL. KNHNES and KCHS report different self-reported prevalence data by year. The cutoff points for the severity distributions of each disease were determined according to the averages of the mean values of the EQ-5D-3L index for the severity levels of the health states. Finally, these cutoff points were applied to the disease prevalence data from KNHNES and KCHS in order to estimate the disease severity distributions. We used pooled data from KNHNES (obtained between 2005 and 2012) and KCHS (2008–2012), respectively. All statistical analyses were conducted using SPSS 21.0 software.
Fig. 1

Approach used in this study to estimate disease severity distribution

Results

The basic characteristics and self-perceived HRQoL values of the study participants are listed in Table 1. In total, 50.6 % of the study participants (182 participants) were female. Participants in their 40s and residents of Gyunggi were the largest groups. These characteristics are similar to those reported for the general public in Seoul, Inchon, and Gyunggi. The mean EQ-5D index was 0.971 (standard deviation 0.08; median 1.000).
Table 1

Basic characteristics of the study participants

 

Number

Percent

Gender

Female

182

50.6

Male

178

49.4

Age group (years)

19–29

67

18.6

30–39

73

20.3

40–49

81

22.5

50–59

70

19.4

60-

69

19.2

Region

Seoul

148

41.1

Incheon

41

11.4

Gyunggi

171

47.5

Education level (years)

−8

6

1.7

9–11

33

9.2

12–15

224

62.2

16-

97

26.9

  

Mean (standard deviation)

Self perceived health related quality of life (EQ-5D-3L index)

0.971 (0.08)

Table 2 presents the means and standard deviations of the EQ-5D-3L indices according to the severity levels of 35 diseases. The raw survey data related EQ-5D-3L indices are available in the Additional file 1. The cutoff points were also calculated using the averages of the mean values of the EQ-5D-3L index for the severity levels of the health states. In the case of asthma, the EQ-5D-3L indices according to severity level were 0.956 (controlled), 0.849 (partially controlled), and 0.717 (uncontrolled). The cutoff points were 0.902 (between controlled and partially controlled) and 0.783 (between partially controlled and uncontrolled).
Table 2

Characteristics of the EQ-5D-3L index for diseases by severity level

No

Disease

Severity level

Response number

Mean

SD

Cut-off

1

Infectious disease

Acute episode, mild

30

0.934

0.068

-

Acute episode, moderate

30

0.802

0.099

0.868

Acute episode, severe

30

0.521

0.236

0.661

2

Diarrhoea

Mild

30

0.753

0.168

-

Moderate

30

0.644

0.203

0.699

Severe

30

0.353

0.287

0.498

3

Angina pectoris

Mild

30

0.687

0.372

-

Moderate

30

0.663

0.318

0.675

Severe

30

0.506

0.324

0.585

4

Heart failure

Mild

30

0.793

0.184

-

Moderate

30

0.688

0.236

0.741

Severe

30

0.478

0.206

0.583

5

Stroke

Long-term consequences, mild

30

0.567

0.276

-

Long-term consequences, moderate

30

0.491

0.287

0.529

Long-term consequences, moderate plus cognition problems

30

0.311

0.348

0.401

Long-term consequences, severe

30

−0.035

0.197

0.138

Long-term consequences, severe plus cognition problems

30

−0.092

0.139

−0.064

6

Asthma

Controlled

30

0.956

0.072

-

Partially controlled

30

0.849

0.139

0.902

Uncontrolled

30

0.717

0.228

0.783

7

COPD & other respiratory problems

Mild

30

0.929

0.108

-

Moderate

30

0.742

0.191

0.835

Severe

30

0.620

0.245

0.681

8

Dementia

Mild

30

0.840

0.175

-

Moderate

30

0.648

0.223

0.744

Severe

30

0.181

0.407

0.415

9

Multiple sclerosis

Mild

30

0.785

0.153

-

Moderate

30

0.648

0.197

0.717

Severe

30

0.556

0.266

0.602

10

Epilepsy

Treated, seizure free

30

0.686

0.207

-

Treated, with recent seizure

30

0.545

0.225

0.615

Untreated

30

0.542

0.258

0.544

Severe

30

0.345

0.303

0.443

11

Parkinson’s disease

Mild

30

0.849

0.127

-

Moderate

30

0.686

0.191

0.767

Severe

30

0.344

0.333

0.515

12

Alcohol use disorder

Mild

30

0.755

0.220

-

Moderate

30

0.730

0.207

0.743

Severe

30

0.494

0.247

0.612

13

Fetal alcohol syndrome

Mild

30

0.850

0.136

-

Moderate

30

0.731

0.135

0.79

Severe

30

0.426

0.256

0.579

14

Anxiety disorder

Mild

30

0.927

0.080

-

Moderate

30

0.835

0.117

0.881

Severe

30

0.612

0.282

0.723

15

Major depressive disorder

Mild

30

0.813

0.157

-

Moderate

30

0.436

0.345

0.624

Severe

30

0.159

0.366

0.298

16

Intellectual disability

Mild

30

0.662

0.311

-

Moderate

30

0.685

0.215

0.673

Severe

30

0.444

0.291

0.564

Profound

30

0.383

0.286

0.414

17

Hearing loss

Mild

30

0.877

0.167

-

Moderate

30

0.720

0.204

0.799

Severe

30

0.710

0.170

0.715

Profound

30

0.528

0.206

0.619

Complete

30

0.366

0.312

0.447

18

Hearing loss with ringing

Mild

30

0.675

0.319

-

Moderate

30

0.635

0.248

0.655

Severe

30

0.528

0.317

0.581

Profound

30

0.454

0.282

0.491

Complete

30

0.368

0.287

0.411

19

Distant vision

Mild impairment

30

0.949

0.109

-

Moderate impairment

30

0.719

0.199

0.834

Severe impairment

30

0.429

0.333

0.574

Blindness

30

0.221

0.296

0.325

20

Low back pain

Acute without leg pain

30

0.446

0.363

-

Acute with leg pain

30

0.308

0.357

0.377

Chronic without leg pain

30

0.342

0.351

0.325

Chronic with leg pain

30

0.188

0.272

0.265

21

Neck pain

Acute mild

30

0.694

0.169

-

Acute severe

30

0.504

0.28

0.599

Chronic mild

30

0.544

0.209

0.524

Chronic severe

30

0.361

0.323

0.453

22

Musculoskeletal problems: leg

Mild

30

0.786

0.068

-

Moderate

30

0.726

0.057

0.756

Severe

30

0.539

0.185

0.633

23

Musculoskeletal problems: arms

Mild

30

0.438

0.354

-

Moderate

30

0.317

0.320

0.377

24

Musculoskeletal problems: generalised

Moderate

30

0.360

0.314

-

Severe

30

0.111

0.307

0.235

25

Abdominopelvic problem

Mild

30

0.882

0.063

-

Moderate

30

0.699

0.156

0.791

Severe

30

0.238

0.250

0.469

26

Disfigurement

Level 1

30

0.866

0.093

-

Level 2

30

0.736

0.186

0.801

Level 3

30

0.662

0.26

0.699

27

Disfigurement: with itch or pain

Level 1

30

0.721

0.183

-

Level 2

30

0.551

0.255

0.636

Level 3

30

0.145

0.272

0.348

28

Motor impairment

Mild

30

0.817

0.151

-

Moderate

30

0.648

0.151

0.733

Severe

30

0.129

0.330

0.389

29

Motor plus cognitive impairment

Mild

30

0.622

0.236

-

Moderate

30

0.394

0.335

0.508

Severe

30

−0.004

0.237

0.195

30

Traumatic brain injury

long-term consequences, minor with or without treatment

30

0.513

0.254

-

long-term consequences, moderate with or without treatment

30

0.161

0.279

0.337

long-term consequences, severe with or without treatment

30

−0.001

0.319

0.080

31

Anemia

Mild

60

0.802

0.287

-

Moderate

60

0.596

0.313

0.699

Severe

60

0.416

0.335

0.506

32

Allergic rhinitis and conjunctivitis

Mild

30

0.694

0.288

-

Moderate

30

0.645

0.269

0.670

33

Annoyance

Mild

30

0.805

0.264

-

Severe

30

0.676

0.305

0.740

34

Sleep disturbance

Mild

30

0.894

0.111

-

Severe

30

0.807

0.208

0.851

35

Cognitive impairment in children

Mild

30

0.838

0.258

-

Severe

30

0.816

0.181

0.827

SD standard deviation, COPD chronic obstructive pulmonary disease

Some health states had negative mean values for their EQ-5D-3L indices. For example, the mean values of the EQ-5D-3L indices for “stroke: long-term consequences, severe” and “stroke: long-term consequences, severe plus cognition problems” were −0.035 and −0.092, respectively. Consequently, the cutoff point between “stroke: long-term consequences, severe” and “stroke: long-term consequences, severe plus cognition problems” was also negative at −0.064. However, the other cutoff values were all positive.

The severity distributions for 8 diseases were estimated using these cutoff values: asthma, angina, stroke, chronic obstructive pulmonary disease (COPD), major depressive disorder, musculoskeletal problem in legs, anemia, and allergic rhinitis and conjunctivitis (Table 3). The severity distributions of the other diseases, such as dementia and epilepsy, could not be estimated because the participants who had these diseases (such as dementia or epilepsy) did not have an EQ −5D profile in both KNHNES and KCHS. Overall, the proportion of participants with mild disease severity was larger than the proportion of moderate or severe disease severity for each disease. For example, the proportions of “stroke: long-term consequences, mild” were 86.4 % (KNHNES) and 81.0 % (KCHS), whereas those of “stroke: long-term consequences, severe” were only 1.9 % (KNHNES) and 5.0 % (KCHS). In the case of major depressive disorder, the distributions of severity were 88.8 % (mild), 9.8 % (moderate), and 1.5 % (severe) according to KNHNES. However, the proportions of severe cases with asthma, COPD, and musculoskeletal problems in the legs were >10 %. In particular, the severity distributions for asthma were 52.4 % (controlled), 14.4 % (partially controlled), and 33.2 % (uncontrolled) according to KCHS.
Table 3

Estimated disease severity distributions

No

Disease

Severity level

KNHNES

KCHS

%

Year

%

Year

3

Angina pectoris

Mild

87.6

2005–2012

88.2

2008–2012

Moderate

3.1

2.1

Severe

9.3

9.7

5

Stroke

Long-term consequences, mild

86.4

2005–2012

81.0

2008–2012

Long-term consequences, moderate

4.9

5.4

Long-term consequences, moderate plus cognition problems

6.5

6.0

Long-term consequences, severe

1.9

5.0

Long-term consequences, severe plus cognition problems

0.2

2.6

6

Asthma

Controlled

53.9

2005–2012

52.4

2008–2012

Partially controlled

17.9

14.4

Uncontrolled

28.2

33.2

7

COPD & other respiratory problems

Mild

66.5

2005–2012

  

Moderate

23.3

  

Severe

10.1

  

15

Major depressive disorder

Mild

88.8

2007–2012

86.1

2009–2012

Moderate

9.8

10.8

Severe

1.5

3.1

20

Low back pain

Acute without leg pain

  

97.7

2008

Acute with leg pain

  

0.2

Chronic without leg pain

  

0.3

Chronic with leg pain

  

1.7

22

Musculoskeletal problems: leg

Mild

74.5

2005–2012

71.2

2008

Moderate

14.3

17.0

Severe

11.2

11.7

31

Anemia

Mild

91.9

2005–2009

90.4

2008,2012

Moderate

6.1

6.9

Severe

2.1

2.7

32

Allergic rhinitis and conjunctivitis

Mild

97.9

2005–2009

98.0

2008–2012

Moderate

2.1

2.0

KNHNES Korean National Health and Nutrition Examination Surveys, KCHS Korean Community Health Survey, COPD chronic obstructive pulmonary disease

Discussion

We have estimated the severity distributions of 8 diseases (asthma, angina, stroke, COPD, major depressive disorder, musculoskeletal problem in legs, anemia, and allergic rhinitis and conjunctivitis) using EQ-5D-3L. We performed face-to-face interviews, in which the survey participants completed the EQ-5D-3L for a hypothetical person as depicted by the lay descriptions explaining the health states of diseases. The EQ-5D-3L index was calculated for each health state using survey data obtained by this study, and the cutoff points for the severity distributions of each disease were determined according to the averages of the means of the EQ-5D-3L index for the severity levels of the health states. These cutoff points were applied to disease prevalence data obtained from population surveys performed at the national level (KNHNES and KCHS), and the severity distributions for each disease were estimated.

In terms of methodology, this study approach is similar to the indirect elicitation methods used to generate HRQoL weights [14]. The generic preference-based instruments such as EQ-5D and Health Utilities Index are generally used to evaluate status of health states developed to cover key aspects including physical and mental health in the indirect elicitation method. Although the measured aspects of health will differ depending on the instrument, it is easy to perform similar studies and comparability can be assured across diseases and countries. If there are prevalence data about HRQoL in other countries, it will be worth conducting similar studies in situations that lack data on disease severity distributions.

There is a paucity of data on disease severity distributions, although data on prevalence are relatively accessible [7]. Even though data on severity distributions are available, generalizability is limited in terms of the study designs used to collect data [1517] and evaluate disease severity [18]. If there are national survey data on severity distributions in a certain country [19], the applicability of that data to other countries will be restricted due to differences in race, socio-demographics, and healthcare system accessibility. When collecting epidemiologic data, including prevalence and incidence, data on severity distributions are also needed to fundamentally solve this problem.

In our present study, we used 2 different population survey data sets (KNHNES and KCHS) to estimate the severity distributions. The estimated patterns for severity distribution using KNHNES and KCHS were quite similar. For example, in the case of angina pectoris, the severity distributions according to KNHNES were 87.6 % (mild), 3.1 % (moderate), and 9.3 % (severe). The severity distributions according to KCHS were 88.2 % (mild), 2.1 % (moderate), and 9.7 % (severe). These consistent results between the 2 population surveys data indicate that the reliability of this study is fair.

Overall, the proportion of participants with mild disease severity tended to be larger than moderate or severe disease severity for each disease included in this study. Because KNHNES and KCHS surveyed the general public, there is a possibility that the proportions of moderate or severe disease were underestimated. When compared with the results of other epidemiologic studies, some studies show similar results, whereas other studies demonstrate divergent results. For example, Lee et al reported that 51.8 % of their participants were stage 1 on the BODE index (reflecting the systemic nature of COPD), followed by 24.3 % at stage 2, 16.3 % at stage 3, and 7.6 % at stage 4 [18]. In this study, we estimated the severity distributions of COPD as follows: 66.5 % (mild), 23.3 % (moderate), and 10.1 % (severe). Furthermore, Cho et al suggested that the majority of individuals with low-back pain demonstrate low-intensity or disabling pain [17]. In this study, we also estimated that the proportion of cases with complicated, low-back pain was small.

According to a multinational survey on asthma, however, only 27 % of patients from South Korea reported having asthma that was well or completely controlled [20]. In our present study, we predicted that 53.9 and 52.4 % of people with asthma were in control of their disease according to KNHNES and KCHS data, respectively. These results could be due to limitations in the EQ-5D-3L used to evaluate asthma HRQoL. That is, EQ-5D-3L might not reflect all aspects of asthma, so further studies that use similar methods as this study, including disease-specific HRQoL instruments, will be needed to verify the reasons for the gap between reports.

This study has several limitations. First, we estimated the EQ-5D-3L indices and cutoff points for 35 diseases by severity, but the severity distributions were only determined for 8 diseases due to limitations in the population survey data. In KNHNES and KCHS, there are no prevalence-based data for undetermined diseases such as Parkinson’s diseases or sleep disturbance. However, if prevalence-based data with HRQoL are generated, we would be able to estimate the severity distributions of other diseases using the cutoff points from our analyses. Second, the survey participants were asked to complete EQ-5D-3L for hypothetical persons in the order of good health states. If our participants had completed the EQ-5D-3L for hypothetical people in the order of bad health states, different EQ-5D-3L indices might have been estimated. Third, when applying the cut-off points from the survey to the EQ-5D-3L indices of the KNHES and KCHS, we could not consider comorbidity in the KNHES and KCHS due to the limitation of data source. A person with a certain disease may have other diseases in the KNHES and KCHS, therefore, reported EQ-5D-3L indices in a certain disease may be influenced by concomitant diseases. Comparing a person without any comorbidity in a certain disease, the reported EQ-5D-3L indices in a certain disease would be underestimated and the proportions of severe cases would be overestimated.

Conclusions

Using EQ-5D-3L, our present study has provided the severity distributions of 8 diseases (asthma, angina, stroke, COPD, major depressive disorder, musculoskeletal problem in legs, anemia, and allergic rhinitis and conjunctivitis) in the Korean population. Using our approach, valid disease burden could be calculated in the future in South Korea and other countries using disease severity distributions.

Abbreviations

COPD: 

chronic obstructive pulmonary disease

DALYs: 

disability adjusted life years

GBD: 

global burden of disease

HRQoL: 

health related quality of life

KCHS: 

Korean Community Health Survey

KNHNES: 

Korean National Health and Nutrition Examination Surveys

YLDs: 

years lived with disability

YLLs: 

years of life lost

Declarations

Acknowledgements

The authors would like to thank Gallup Korea for help in conducting survey. The authors also are grateful to the participants of survey.

Funding

This study was funded by the Korea Ministry of Environment (MOE) as “the Environmental Health Action Program (grant number: 2014001350001).”

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Department of Preventive Medicine, University of Ulsan College of Medicine
(2)
Department of Preventive Medicine, Korea University College of Medicine
(3)
Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine

References

  1. Murray CJ. Quantifying the burden of disease: the technical basis for disability-adjusted life years. Bull World Health Organ. 1994;72(3):429–45.PubMedPubMed CentralGoogle Scholar
  2. Murray CJ, Lopez AD. Global mortality, disability, and the contribution of risk factors: Global burden of disease study. Lancet. 1997;349(9063):1436–42.View ArticlePubMedGoogle Scholar
  3. Murray CJ, Ezzati M, Flaxman AD, Lim S, Lozano R, Michaud C, et al. GBD 2010: design, definitions, and metrics. Lancet. 2012;380(9859):2063–6.View ArticlePubMedGoogle Scholar
  4. Ministry of Health. Ways and means: A report on methodology from the New Zealand burden of diseases, injuries and risk factors study, 2006–2016. Wellington: Ministry of Health; 2012.Google Scholar
  5. Haagsma JA, Polinder S, Cassini A, Colzani E, Havelaar AH. Review of disability weight studies: comparison of methodological choices and values. Popul Health Metr. 2014;12:20.View ArticlePubMedPubMed CentralGoogle Scholar
  6. Salomon JA, Vos T, Hogan DR, Gagnon M, Naghavi M, Mokdad A, et al. Common values in assessing health outcomes from disease and injury: disability weights measurement study for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2129–43.View ArticlePubMedGoogle Scholar
  7. Vos T, Flaxman AD, Naghavi M, Lozano R, Michaud C, Ezzati M, et al. Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2163–96.View ArticlePubMedGoogle Scholar
  8. The SF-12®: An Even Shorter Health Survey. Version 2.0. http://www.sf-36.org/tools/sf12.shtml . Accessed 28 Jan 2016.
  9. Supplement to: Vos T, Flaxman AD, Naghavi M, Lozano R, Michaud C, Ezzati M, et al. Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380: 2163-2196.Google Scholar
  10. Lee YK, Nam HS, Chuang LH, Kim KY, Yang HK, Kwon IS. South Korean time trade-off values for EQ-5D health states: modeling with observed values for 101 health states. Value Health. 2009;12(8):1187–93.View ArticlePubMedGoogle Scholar
  11. Whitehead SJ, Ali S. Health outcomes in economic evaluation: the QALY and utilities. Br Med Bull. 2010;96:5–21.View ArticlePubMedGoogle Scholar
  12. EQ-5D-3L. EuroQol. http://www.euroqol.org/eq-5d-products/eq-5d-3l.html. Accessed 28 Jan 2016.
  13. Son KM, Cho NH, Lim SH, Kim HA. Prevalence and risk factor of neck pain in elderly Korean community residents. J Korean Med Sci. 2013;28(5):680–6.View ArticlePubMedPubMed CentralGoogle Scholar
  14. Kim DS, Lee JH, Lee KH, Lee MG. Prevalence and severity of atopic dermatitis in Jeju Island: a cross-sectional study of 4,028 Korean elementary schoolchildren by physical examination utilizing the three-item severity score. Acta Derm Venereol. 2012;92(5):472–4.View ArticlePubMedGoogle Scholar
  15. Cho NH, Jung YO, Lim SH, Chung CK, Kim HA. The prevalence and risk factors of low back pain in rural community residents of Korea. Spine (Phila Pa 1976). 2012;37(24):2001–10.View ArticleGoogle Scholar
  16. Lee H, Kim S, Lim Y, Gwon H, Kim Y, Ahn JJ, et al. Nutritional status and disease severity in patients with chronic obstructive pulmonary disease (COPD). Arch Gerontol Geriatr. 2013;56(3):518–23.View ArticlePubMedGoogle Scholar
  17. Gupta RS, Springston EE, Warrier MR, Smith B, Kumar R, Pongracic J, et al. The prevalence, severity, and distribution of childhood food allergy in the United States. Pediatrics. 2011;128(1):e9–17.View ArticlePubMedGoogle Scholar
  18. Makino M, Tsuboi K, Dennerstein L. Prevalence of eating disorders: a comparison of Western and non-Western countries. MedGenMed. 2004;6(3):49.PubMedPubMed CentralGoogle Scholar
  19. Schena FP. Epidemiology of end-stage renal disease: International comparisons of renal replacement therapy. Kidney Int. 2000;57:S39–45.View ArticleGoogle Scholar
  20. Thompson PJ1, Salvi S, Lin J, Cho YJ, Eng P, Abdul Manap R, et al. Insights, attitudes and perceptions about asthma and its treatment: findings from a multinational survey of patients from 8 Asia-Pacific countries and Hong Kong. Respirology. 2013;18(6):957–67.View ArticlePubMedGoogle Scholar

Copyright

© Ock et al. 2016

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