Estimation of Utility Weights for Prostate-related Health States in Korea / 예방의학회지

Objectives@#Very limited previous research has investigated the utility weights of prostate-related diseases in the general population in Korea. The purpose of this study was to calculate the utility of prostate-related health states in the Korean general public using the standard gamble (SG) method. @*Methods@#Seven health states for hypothetical prostate cancers, 1 for benign prostate hyperplasia, and 1 for erectile dysfunction were developed based on patient education material and previous publications. In total, 460 responses from the Korean general population were used to analyze the utility of prostate-related health states. Computer-assisted personal interviews were conducted, and utility values were measured using a visual analogue scale (VAS) and SG. Mean utility values were calculated for each prostate-related health state. @*Results@#The mean utility values of prostate cancer derived from SG ranged from 0.281 (metastatic castration-refractory prostate cancer) to 0.779 (localized prostate cancer requiring prostatectomy). The utility value of benign prostate hyperplasia was 0.871, and that of erectile dysfunction was 0.812. The utility values obtained using the SG method in all conditions were higher than the values obtained by VAS. There were no significant demographic variables affecting utility values in multivariate analysis. @*Conclusions@#Our findings might be useful for economic evaluation and utility calculation of screening and interventions for prostate-related conditions in the general population.

Estimating Lifetime Duration of Diabetes by Age and Gender in the Korean Population Using a Markov Model

BACKGROUND@#Duration of type 2 diabetes is clinically important. Duration of morbidity is an independent and critical predictor of developing its complications. This study aims to explore an applicability of a Markov model to estimate the duration of diabetes in the Korean population.@*METHODS@#We constructed the Markov model with two Markov states, diabetes and death, for estimation of duration of diabetes. The cycle of the Markov model was 1 year. Each diabetes onset by 5 years was considered from 30 to 85 years old or above. The endpoint of the Markov was 100 years old. Type 2 diabetes was operationally defined using the 10th revision of International Statistical Classification of Diseases and prescriptions of anti-diabetic drugs from the National Health Insurance Services-National Sample cohort. In each incident and existing prevalence cases, survival probabilities were obtained. Durations of diabetes from the Markov model were compared with those from the DisMod II program. Reductions of life expectancy due to diabetes were defined as differences of life expectancies between diabetic patients and the general public. Sensitivity analyses were also conducted using a cure rate and 95% confidence interval of survival probability.@*RESULTS@#The duration of diabetes gradually decreased with incident age in both genders. In the early 30s, the duration was the largest at 48.9 and 41.9 years in women and men, respectively. In the average incident age group of type 2 diabetes, the late 50s, the reduction of life expectancy due to diabetes was estimated to be about two years in both genders. As annual cure probabilities increased, the durations of diabetes were reduced.@*CONCLUSION@#This study estimated the duration of diabetes using a Markov model. The model seems to work well and diabetes could reduce life expectancy by about 2 years on average. This approach could be useful to estimate the duration of illness, calculate disability-adjusted life years, and conduct economic evaluation studies on interventions for diabetic patients.

Development and Validation of a Novel Generic Health-related Quality of Life Instrument With 20 Items (HINT-20) / 예방의학회지

OBJECTIVES: Few attempts have been made to develop a generic health-related quality of life (HRQoL) instrument and to examine its validity and reliability in Korea. We aimed to do this in our present study. METHODS: After a literature review of existing generic HRQoL instruments, a focus group discussion, in-depth interviews, and expert consultations, we selected 30 tentative items for a new HRQoL measure. These items were evaluated by assessing their ceiling effects, difficulty, and redundancy in the first survey. To validate the HRQoL instrument that was developed, known-groups validity and convergent/discriminant validity were evaluated and its test-retest reliability was examined in the second survey. RESULTS: Of the 30 items originally assessed for the HRQoL instrument, four were excluded due to high ceiling effects and six were removed due to redundancy. We ultimately developed a HRQoL instrument with a reduced number of 20 items, known as the Health-related Quality of Life Instrument with 20 items (HINT-20), incorporating physical, mental, social, and positive health dimensions. The results of the HINT-20 for known-groups validity were poorer in women, the elderly, and those with a low income. For convergent/discriminant validity, the correlation coefficients of items (except vitality) in the physical health dimension with the physical component summary of the Short Form 36 version 2 (SF-36v2) were generally higher than the correlations of those items with the mental component summary of the SF-36v2, and vice versa. Regarding test-retest reliability, the intraclass correlation coefficient of the total HINT-20 score was 0.813 (p<0.001). CONCLUSIONS: A novel generic HRQoL instrument, the HINT-20, was developed for the Korean general population and showed acceptable validity and reliability.

Exploratory Study of Dimensions of Health-related Quality of Life in the General Population of South Korea / 예방의학회지

OBJECTIVES: This study aimed to explore dimensions in addition to the 5 dimensions of the 5-level EQ-5D version (EQ-5D-5L) that could satisfactorily explain variation in health-related quality of life (HRQoL) in the general population of South Korea. METHODS: Domains related to HRQoL were searched through a review of existing HRQoL instruments. Among the 28 potential dimensions, the 5 dimensions of the EQ-5D-5L and 7 additional dimensions (vision, hearing, communication, cognitive function, social relationships, vitality, and sleep) were included. A representative sample of 600 subjects was selected for the survey, which was administered through face-to-face interviews. Subjects were asked to report problems in 12 health dimensions at 5 levels, as well as their self-rated health status using the EuroQol visual analogue scale (EQ-VAS) and a 5-point Likert scale. Among subjects who reported no problems for any of the parameters in the EQ-5D-5L, we analyzed the frequencies of problems in the additional dimensions. A linear regression model with the EQ-VAS as the dependent variable was performed to identify additional significant dimensions. RESULTS: Among respondents who reported full health on the EQ-5D-5L (n=365), 32% reported a problem for at least 1 additional dimension, and 14% reported worse than moderate self-rated health. Regression analysis revealed a R2 of 0.228 for the original EQ-5D-5L dimensions, 0.200 for the new dimensions, and 0.263 for the 12 dimensions together. Among the added dimensions, vitality and sleep were significantly associated with EQ-VAS scores. CONCLUSIONS: This study identified significant dimensions for assessing self-rated health among members of the general public, in addition to the 5 dimensions of the EQ-5D-5L. These dimensions could be considered for inclusion in a new preference-based instrument or for developing a country-specific HRQoL instrument.

How Can We Use Hospital-Standardized Mortality Ratio as a Quality Indicator of Hospital Care in Korea? / 보건행정학회지

The hospital standardized mortality ratio (HSMR) is a widely used generic measure for assessing quality of hospital care in many countries. However, the validity of HSMR as a quality indicator is still controversial. We critically reviewed characteristics of HSMR and suggested how to use HSMR as a quality indicator in the Korean setting. The association between HSMR and other quality measures of hospital care is inconclusive. In addition current HSMR model has shortcomings in risk adjustment because of the lack of clinical data, accuracy of disease coding, coding variation among hospitals, end-of-life care issues, and so on. Therefore, HSMR should be used as an indicator for improvement, not for judgement such as public reporting and pay-for-performance. More efforts will be needed to tackle practical and methodological weaknesses of HSMR in the Korean setting.

Evaluation of the Validity of Risk-Adjustment Model of Acute Stroke Mortality for Comparing Hospital Performance / 보건행정학회지

BACKGROUND: The purpose of this study was to develop risk-adjustment models for acute stroke mortality that were based on data from Health Insurance Review and Assessment Service (HIRA) dataset and to evaluate the validity of these models for comparing hospital performance. METHODS: We identified prognostic factors of acute stroke mortality through literature review. On the basis of the avaliable data, the following factors was included in risk adjustment models: age, sex, stroke subtype, stroke severity, and comorbid conditions. Survey data in 2014 was used for development and 2012 dataset was analysed for validation. Prediction models of acute stroke mortality by stroke type were developed using logistic regression. Model performance was evaluated using C-statistics, R2 values, and Hosmer-Lemeshow goodness-of-fit statistics. RESULTS: We excluded some of the clinical factors such as mental status, vital sign, and lab finding from risk adjustment model because there is no avaliable data. The ischemic stroke model with age, sex, and stroke severity (categorical) showed good performance (C-statistic=0.881, Hosmer-Lemeshow test p=0.371). The hemorrhagic stroke model with age, sex, stroke subtype, and stroke severity (categorical) also showed good performance (C-statistic=0.867, Hosmer-Lemeshow test p=0.850). CONCLUSION: Among risk adjustment models we recommend the model including age, sex, stroke severity, and stroke subtype for HIRA assessment. However, this model may be inappropriate for comparing hospital performance due to several methodological weaknesses such as lack of clinical information, variations across hospitals in the coding of comorbidities, inability to discriminate between comorbidity and complication, missing of stroke severity, and small case number of hospitals. Therefore, further studies are needed to enhance the validity of the risk adjustment model of acute stroke mortality.

Disability-Adjusted Life Years for Maternal, Neonatal, and Nutritional Disorders in Korea

Maternal and child health is an important issue throughout the world. Given their impact on maternal and child health, nutritional issues need to be carefully addressed. Accordingly, the effect of maternal, child, and nutritional disorders on disability-adjusted life years (DALYs) should be calculated. The present study used DALYs to estimate the burden of disease of maternal, neonatal, and nutritional disorders in the Korean population in 2012. For this purpose, we used claim data of the Korean National Health Insurance Service, DisMod II, and death data of the Statistics Korea and adhered to incidence-based DALY estimation methodology. The total DALYs per 100,000 population were 376 in maternal disorders, 64 in neonatal disorders, and 58 in nutritional deficiencies. The leading causes of DALYs were abortion in maternal disorders, preterm birth complications in neonatal disorders, and iron-deficiency anemia in nutritional deficiencies. Our findings shed light on the considerable burden of maternal, neonatal, and nutritional conditions, emphasizing the need for health care policies that can reduce morbidity and mortality.

Health Group and Disease Group's Perceptions of Health and Health-related Quality of Life: a Focus Group Study and In-depth Interviews

BACKGROUND: This study aimed to understand and explore perception of healthy adults and chronically ill adults on health and health-related quality of life (HRQoL). METHODS: Data were collected by open questions using a focus group discussion for healthy adults (N=6) and in-depth interviews for chronically ill adults (N=6). Previously developed 34 HRQoL items also were offered and participants were asked to select the five most important HRQoL items among them. RESULTS: Findings were elicited along the following themes: health, HRQoL, health maintenance strategies, and elements affecting health. The definition on "being healthy" by healthy participants had a variety of standards and required several conditions to be fulfilled. Whereas chronically ill adults have more flexible perception about the coexistence of health and disease. Health dimensions were thought to affect each other, and physical and mental health dimension were selected as the most important items. As for the five most important HRQoL items, both group participants selected mental health dimension than physical or social health dimensions. Health maintenance strategies were similar in both groups except more healthcare service use in chronically ill adults. CONCLUSIONS: This study shows the difference of perception on health and HRQoL between health group and disease group in Korea. It can be used for developing the HRQoL assessment tool reflecting the perception of Korean people.

Assessing Reliability of Medical Record Reviews for the Detection of Hospital Adverse Events / 예방의학회지

OBJECTIVES: The purpose of this study was to assess the inter-rater reliability and intra-rater reliability of medical record review for the detection of hospital adverse events. METHODS: We conducted two stages retrospective medical records review of a random sample of 96 patients from one acute-care general hospital. The first stage was an explicit patient record review by two nurses to detect the presence of 41 screening criteria (SC). The second stage was an implicit structured review by two physicians to identify the occurrence of adverse events from the positive cases on the SC. The inter-rater reliability of two nurses and that of two physicians were assessed. The intra-rater reliability was also evaluated by using test-retest method at approximately two weeks later. RESULTS: In 84.2% of the patient medical records, the nurses agreed as to the necessity for the second stage review (kappa, 0.68; 95% confidence interval [CI], 0.54 to 0.83). In 93.0% of the patient medical records screened by nurses, the physicians agreed about the absence or presence of adverse events (kappa, 0.71; 95% CI, 0.44 to 0.97). When assessing intra-rater reliability, the kappa indices of two nurses were 0.54 (95% CI, 0.31 to 0.77) and 0.67 (95% CI, 0.47 to 0.87), whereas those of two physicians were 0.87 (95% CI, 0.62 to 1.00) and 0.37 (95% CI, -0.16 to 0.89). CONCLUSIONS: In this study, the medical record review for detecting adverse events showed intermediate to good level of inter-rater and intra-rater reliability. Well organized training program for reviewers and clearly defining SC are required to get more reliable results in the hospital adverse event study.

Assessment of the Quality of Clinical Practice Guidelines in Korea Using the AGREE Instrument

The objective of this study was to conduct the systematic evaluation of methodological quality of clinical practice guidelines (CPGs) in Korea. The authors conducted a very comprehensive literature search to identify potential CPGs for evaluation. CPGs were selected which were consistent with a predetermined criteria. Four reviewers evaluated the quality of the CPGs using the Appraisal of Guidelines, Research and Evaluation (AGREE) Instrument. AGREE item scores and standardized domain scores were calculated. The inter-rater reliability of each domain was evaluated using the intra-class correlation coefficient (ICC). Consequently, 66 CPGs were selected and their quality evaluated. ICCs for CPG appraisal using the AGREE Instrument ranged from 0.626 to 0.877. Except for the "Scope and Purpose" and "Clarity and Presentation domains", 80% of CPGs scored less than 40 in all other domains. This review shows that many Korean research groups and academic societies have made considerable efforts to develop CPGs, and the number of CPGs has increased over time. However, the quality of CPGs in Korea were not good according to the AGREE Instrument evaluation. Therefore, we should make more of an effort to ensure the high quality of CPGs.

Effect of EuroQol-5 Dimension on Visual Analogue Scale in Korean Population

BACKGROUND: The EuroQol-5 Dimension (EQ-5D) is the most frequently used questionnaire in cost-utility studies such as the quality-adjusted life year measure. Nevertheless, little attention has been paid to the relationship between an individual's visual analogue scale (VAS) score and EQ-5D dimensions. The objective of this study was to assess the relationship between the EQ-5D and VAS quality of life measures after adjusting for socio-demographic factors in the Korean general population. METHODS: The Fourth Korea National Health and Nutrition Examination Survey, which is a national representative sample, was used to analyze the impact of the EQ-5D dimensions on the VAS. The known-group construct validity of the VAS was assessed by factors that included age, income and comorbidities. The ordinary linear regression models were applied to test for the effect of the EQ-5D dimensions after adjusting for socio-demographic and clinical factors. RESULTS: We found that the VAS showed good construct validity. The VAS significantly declined as age increased, and as education and income levels decreased. VAS scores decreased for all EQ-5D dimensions as the response level rose. The explanatory power of the VAS increased from 23.0% in the first model, which included only the EQ-5D dimensions and levels, to 25.0% in the full model, which included socio-demographic and clinical factors. CONCLUSIONS: While the EQ-5D dimensions were significant factors in determining the VAS, they did not, however, explain a sufficient amount of variance in the VAS. Further research is required on adding more dimensions to the EQ-5D preference-based instrument.

Psychometric Properties of the Korean Short Form-36 Health Survey Version 2 for Assessing the General Population

PURPOSE: To evaluate the psychometric properties of the Korean short form-36 health survey version 2 for assessing the general population and to provide normative data on the general population. METHODS: Six hundred members of the general Korean population were recruited using a multistage quota sampling method. Data quality was evaluated in terms of the completeness of the data and the response consistency index. Each psychometric property was evaluated using descriptive statistics, item internal consistency, item discriminant validity, known-group validity, internal consistency reliability, and exploratory factor analysis. RESULTS: The rate of missing data was low, and the rate of consistent responses was similar to conventional criteria. Item internal consistency was acceptable across all scales, whilst item discriminant validity was satisfactory for five of the eight scales. Social functioning was the least acceptable in terms of not only item discriminant validity but also item consistency reliability (Cronbach's alpha = .64). Test-retest Pearson correlation coefficients ranged from .54 to .80. In known group comparison, male sex, age <60 years, high educational status, and the absence of any comorbidities were associated with higher scores than their counterparts. Item factor analysis yields the presence of six factors, accounting for 68.8% of the variance. CONCLUSION: The findings of this study generally support the use of the Korean short form-36 version 2 for evaluating the general population, although caution is recommended when interpreting the vitality, social functioning, and mental health scales. Further research is needed in Korea.

Factors Affecting Health-Related Quality of Life in Persons with Stroke Using SF-6D

BACKGROUND: The SF-6D, derived from the SF-36, is a preference-based instrument measuring health-related quality of life (HRQOL). Using this tool, we measured the HRQOL of persons disabled by stroke dwelling in Gyeongju city and identified factors affecting the HRQOL. METHODS: As of March 2008, 991 persons who had had a stroke and were aged 50 and over were identified on the Gyeongju city disabled registry. Interviewers specifically trained for this face-to-face survey gathered pertinent information including general and clinical characteristics from June to October 2008. In addition, the health status was measured using the Modified Rankin Scale, the Barthel ADL index, and the SF-36. The SF-6D index was derived from the SF-36. We analyzed the known-group construct validity and convergent validity. Finally, we performed multiple regression analyses to identify factors affecting the HRQOL. RESULTS: Of the 991 potential subjects, 498 persons participated in the interviews (response rate: 50.3%). The SF-6D indices for females and those aged 70 and over were lower than indices for males and those aged 60 and less. Correlation coefficients between the Modified Rankin Scale, the Barthel index, and the SF-6D index were relatively high (-0.533 and 0.555, respectively) and statistically significant (P<0.001). Multiple regression analyses showed that sex, age, smoking, alcohol use, comorbidity, the Modified Rankin Scale, and the Barthel index had an effect on the SF-6D index of persons with stroke, and the Barthel index was the most important factor. CONCLUSIONS: Our results indicate that the SF-6D can be a valid tool for evaluating health states of persons disabled by stroke, and functional limitation was the main factor affecting the HRQOL.

PhactaManager: A Clinical Trial Management System Incorporating an XML Layer as a Database-Independent Processing Platform / 대한의료정보학회지

OBJECTIVE: Clinical trials are the most time-consuming and expensive part of the drug development process. Clinical Trial Management Systems (CTMSs) help sponsors of clinical trials manage all aspects of planning, performance, and reporting. Most conventional systems provide data processing functions using database management system (DBMS) procedures, which cause DBMS dependency problems. Thus, it is hard to handle the system by researchers who are unfamiliar with database. It is also difficult to share Electronic Case Report Forms (eCRFs) between institutions because conventional systems rely on specific software. METHODS: PhactaManager was developed for solving these problems by introducing an XML Layer in the application tier using an Entity-Attribute-Value model in the database tier. RESULTS: PhactaManager is a three-tier clinical trial management system that has an XML layer. The XML Layer provides a common DBMS independent eCRF document processing platform. Also we developed XML based eCRF Grammar to describe eCRF documents. The XML data elements described by eCRF grammar was constitute to eCRF by PhactaDesigner which an eCRF document design program. CONCLUSION: We achieved DBMS independency by implementing the XML Layer in PhactaManager. The Development of the eCRF Grammar enables the standardization of eCRF design, data correction and data sharing in multicenter clinical trial.

Body Mass Index and Risk of Hemorrhagic Stroke in Korean Adults: Case-control Study / 예방의학회지

OBJECTIVES: To evaluate the association between body mass index (BMI) and hemorrhagic stroke. METHODS: A case-control study was conducted on 2,712 persons (904 cases, 904 hospital controls, and 904 community controls) participating in an Acute Brain Bleeding Analysis study from October 2002 to March 2004. Two controls for each case were matched according to age and gender. The information was obtained by trained interviewers using standardized questionnaire. A conditional logistic regression model was used to estimate the association between BMI and the frequency of having a hemorrhagic stroke. RESULTS: Obese men (25.0 < or = BMI < 30.0 kg/m2) had an odds ratios (OR) of 1.39 (95% CI 1.03 to 1.87) a hemorrhagic stroke, compared to men with a normal BMI (18.5 to 24.9 kg/m2). Conversely, women with lower BMI had a higher risk of having hemorrhagic stroke. With respect to subtypes of hemorrahagic stroke, we observed about a three-fold increase in the risk of intracerebral hemorrhage (ICH) in the highly obese group. However, these trends were not significant in patients with subarachnoid hemorrhages. CONCLUSIONS: Obesity was identified as one of the risk factors in hemorrhagic stroke, in particular ICH. Conversely, in women, a lean body weight increases the risk of hemorrhagic stroke. Consequently, managing one\s weight is essential to reduce the risks of hemorrhagic stroke.