• Health Policy and Management
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• v.26 no.1
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• pp.71-78
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• 2016

The value of using health insurance claim database is continuously rising in healthcare research. In studies where comorbidities act as a confounder, comorbidity adjustment holds importance. Yet researchers are faced with a myriad of options without sufficient information on how to appropriately adjust comorbidity. The purpose of this study is to assist in selecting an appropriate index, look back period, and data range for comorbidity adjustment. No consensus has been formed regarding the appropriate index, look back period and data range in comorbidity adjustment. This study recommends the Charlson comorbidity index be selected when predicting the outcome such as mortality, and the Elixhauser's comorbidity measures be selected when analyzing the relations between various comorbidities and outcomes. A longer look back period and inclusion of all diagnoses of both inpatient and outpatient data led to increased prevalence of comorbidities, but contributed little to model performance. Limited data range, such as the inclusion of primary diagnoses only, may complement limitations of the health insurance claim database, but could miss important comorbidities. This study suggests that all diagnoses of both inpatients and outpatients data, excluding rule-out diagnosis, be observed for at least 1 year look back period prior to the index date. The comorbidity index, look back period, and data range must be considered for comorbidity adjustment. To provide better guidance to researchers, follow-up studies should be conducted using the three factors based on specific diseases and surgeries.

• Health Policy and Management
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• v.21 no.4
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• pp.541-564
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• 2011

This study aimed to investigate health outcome of acute myocardial infarction (AMI) patients such as mortality and length of stay in hospital and to identify factors associated with the health outcome according to the comorbidity index. Nation-wide representative samples of 3,748 adult inpatients aged between 20-85 years with acute myocardial infarction were derived from the Korea National Hospital Discharge Injury Survey, 2005-2008. Comorbidity index was measured using the Charlson Comorbidity Index (CCI). The data were analyzed using t-test, ANOVA, multiple regression, logistic regression analysis in order to investigate the effect of comorbidity on health outcome. According to the study results, the factors associated with length of hospital stay of acute myocardial infarction patients were gender, insurance type, residential area scale, admission route, PCI perform, CABG perform, and CCI. The factors associated with mortality of acute myocardial infarction patients were age, admission route, PCI perform, and CCI. CCI with a higher length of hospital stay and mortality also increased significantly. This study demonstrated comorbidity risk adjustment for health outcome and presented important data for health care policy. In the future study, more detailed and adequate comorbidity measurement tool should be developed, so patients' severity can be adjusted accurately.

• Journal of Preventive Medicine and Public Health
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• v.42 no.4
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• pp.267-273
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• 2009

Objectives : To compare the performance of three comorbidity measurements (Charlson comorbidity index, Elixhauser s comorbidity and comorbidity selection) with the effect of different comorbidity lookback periods when predicting in-hospital mortality for patients who underwent percutaneous coronary intervention. Methods : This was a retrospective study on patients aged 40 years and older who underwent percutaneous coronary intervention. To distinguish comorbidity from complications, the records of diagnosis were drawn from the National Health Insurance Database excluding diagnosis that admitted to the hospital. C-statistic values were used as measures for in comparing the predictability of comorbidity measures with lookback period, and a bootstrapping procedure with 1,000 replications was done to determine approximate 95% confidence interval. Results : Of the 61,815 patients included in this study, the mean age was 63.3 years (standard deviation: ${\pm}$10.2) and 64.8% of the population was male. Among them, 1,598 2.6%) had died in hospital. While the predictive ability of the Elixhauser's comorbidity and comorbidity selection was better than that of the Charlson comorbidity index, there was no significant difference among the three comorbidity measurements. Although the prevalence of comorbidity increased in 3 years of lookback periods, there was no significant improvement compared to 1 year of a lookback period. Conclusions : In a health outcome study for patients who underwent percutaneous coronary intervention using National Health Insurance Database, the Charlson comorbidity index was easy to apply without significant difference in predictability compared to the other methods. The one year of observation period was adequate to adjust the comorbidity. Further work to select adequate comorbidity measurements and lookback periods on other diseases and procedures are needed.

• Journal of Preventive Medicine and Public Health
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• v.42 no.1
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• pp.49-58
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• 2009

Objectives : The purpose of the current study was to evaluate the usefulness of the following four comorbidity indices in gastric cancer patients who underwent surgery: Charlson Comorbidity Index(CCI), Cumulative Illness rating scale(CIRS), Index of Co-existent Disease(ICED), and Kaplan-Feinstein Scale(KFS). Methods : The study subjects were 614 adults who underwent surgery for gastric cancer at K hospital between 2005 and 2007. We examined the test-retest and inter-rater reliability of 4 comorbidity indices for 50 patients. Reliability was evaluated with Spearman rho coefficients for CCI and CIRS, while Kappa values were used for the ICED and KFS indices. Logistic regression was used to determine how these comorbidity indices affected unplanned readmission and death. Multiple regression was used for determining if the comorbidity indices affected length of stay and hospital costs. Results : The test-retest reliability of CCI and CIRS was substantial(Spearman rho=0.746 and 0.775, respectively), while for ICED and KFS was moderate(Kappa=0.476 and 0.504, respectively). The inter-rater reliability of the CCI, CIRS, and ICED was moderate(Spearman rho=0.580 and 0.668, and Kappa=0.433, respectively), but for KFS was fair(Kappa=0.383). According to the results from logistic regression, unplanned readmissions and deaths were not significantly different between the comorbidity index scores. But, according to the results from multiple linear regression, the CIRS group showed a significantly increased length of hospital stay(p<0.01). Additionally, CCI showed a significant association with increased hospital costs (p<0.01). Conclusions : This study suggests that the CCI index may be useful in the estimation of comorbidities associated with hospital costs, while the CIRS index may be useful where estimatation of comorbiditie associated with the length of hospital stay are concerned.

• Health Policy and Management
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• v.21 no.4
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• pp.527-540
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• 2011

Some patients tend to visit tertiary hospitals instead of non-tertiary hospitals for minor illnesses, which is a chronic problem within the Korean health care delivery system. In order to reduce the number of patients with minor severity diseases unnecessarily utilizing the tertiary medical services in Korea, the Ministry of Health and Welfare raised the outpatient co-insurance rate for the tertiary hospitals in July, 2009. Another increase in the prescription drug co-insurance rate by the general and tertiary hospitals is scheduled to take place in the second half of 2011. An increase in copayments may discourage the utilization rate of medical services among the underprivileged or patients who require complicated procedures. This study aims to analyze the diabetic patients' utilization rates of tertiary hospitals according to the Comorbidity score. Diabetic patients' data was gathered from the Health Insurance Claims Records in the Health Insurance Review & Assessment Service between 2007-2009. Comorbidity scores are measured by the Charlson Comorbidity Index and the Elixhauser Index. Chi-square and logistic regressions were performed to compare the utilization rates of both insulin-dependents (n=94,026) and non-insulin-dependents (n=1,424,736) in tertiary hospitals. The higher Comorbidity outcomes in the insulin-dependent diabetic patients who didn't visit tertiary hospitals compared to those who did, was expected. However, after adjusting the gender, age, location, first visits and complications, the groups that scored >=1 on the comorbidity scale utilized the tertiary hospitals more than the O score group. Non-insulin-diabetic patients with higher Comorbidity scores visited tertiary hospitals more than patients who received lower grades. This study found that patients suffering from severe diabetes tend to frequently visit the tertiary hospitals in Korea. This result implied that it is important for Korea to improve the quality of its primary health care as well as to consider a co-insurance rate increase.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.22-32
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• 2016

As the number of aged population rapidly goes up, the cases of stroke and the related medical expenses continuously increase. The purpose of this study is to investigate the mortality of stroke patients based on CCI(Charlson Comorbidity Index) by utilizing the Korea National Hospital Discharge Injury Survey, analyzing the factors associated with the mortality of stroke patients. We analyzed 21,494 cases which are classified as the death of strokes aged over 20 years by using the Korea National Hospital Discharge Injury Survey between the year 2005 and 2010. In order to find out the mortality based on CCI and status of comorbidity, we used the technical statistics. We performed a logistic regression analysis to examine the reasons for the mortality of the strokes. We found that the independent variables for the influence of the mortality of strokes include age, type of insurance, residence urban size, size of hospital beds, the location of hospital, admission route, physical therapy, brain surgery, type of stroke, and CCI. This indicates that the effective monitoring on the age, types of stroke, comorbidity is needed. In addition to this, more medical support toward medicaid patients are needed, too. We believe that these results will be used positively for the evaluation of the stroke patients, providing the basic materials for the further research on the establishment of the health-related policy.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.3
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• pp.827-831
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• 2012

To determine the relationship between comorbidity and outcome after radical cystectomy in Chinese patients by using the Adult Comorbidity Evaluation (ACE)-27 index. Two-hundred-and-forty-six patients treated with radical cystectomy at the Second Xiangya Hospital of Central South University, Hunan Province, China between 2000 and 2010 were retrospectively analyzed. Medical records were reviewed for age, gender, delayed time of radical cystectomy, urinary diversion type, pelvic lymphadenectomy status, TNM stage, and pathological grade. Comorbidity information was assessed by the ACE-27 index. The outcome measurement was overall survival. Univariate and multivariate Cox proportional hazards regression analyses were used to determine the association between comorbidity and outcome. The study population consisted of 215 (87.40%) males and 31 (12.60%) females with a mean age of $62{\pm}11$ years. Median duration of follow-up was $47{\pm}31$ months. A total of 151 (61.38%) patents died during follow-up. Of those, 118 (47.97%) had at least one comorbidity. According to the ACE-27 scores, 128 (52.03%) patients had no comorbidity, 79 (32.11%) had mild, 33 (13.41%) had moderate, and 6 (2.45%) had severe comorbidities. Multivariate analysis indicated that moderate (p=0.002) and severe (p<0.001) comorbidity was significantly associated with decreased overall survival. In addition, age ${\geq}70$ years (p=0.002), delayed time of radical cystectomy >12 weeks (p=0.044), pelvic lymphadenectomy status (p=0.014), and TNM stage >T3 (p<0.001) were determined to be independent risk factors of overall survival. Increasing severity of comorbidity statistically correlated with decreased overall survival after radical cystectomy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2672-2679
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• 2012

The study was done to provide basic data of medical quality evaluation after developing the comorbidity disease mortality measurement modeled on the severity-adjustment method of AMI. This study analyzed 699,701 cases of Hospital Discharge Injury Data of 2005 and 2008, provided by the Korea Centers for Disease Control and Prevention. We used logistic regression to compare the risk-adjustment model of the Charlson Comorbidity Index with the predictability and compatibility of our severity score model that is newly developed for calibration. The models severity method included age, sex, hospitalization path, PCI presence, CABG, and 12 variables of the comorbidity disease. Predictability of the newly developed severity models, which has statistical C level of 0.796(95%CI=0.771-0.821) is higher than Charlson Comorbidity Index. This proves that there are differences of mortality, prevalence rate by method of mortality model calibration. In the future, this study outcome should be utilized more to achieve an improvement of medical quality evaluation, and also models will be developed that are considered for clinical significance and statistical compatibility.

• Korea Journal of Hospital Management
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• v.14 no.1
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• pp.23-35
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• 2009

The objectives of the present study is to examine the validity of Charlson Comorbidity Index(CCI) based on medical record data; to utilize the index to determine outcome indexes such as mortality, length of stay and cost for the domestic patients whose have received total hip arthroplasty. Based on medical record date, 1-year Mortality was analyzed to be 0.664 of C statistic. The $R^2$ for the predictability for length of stay and the cost was about 0.0181, 0.1842. Fee of national health insurance and total cost including the cost not covered by insurance, also had statistically significance above 3 points of Charlson point score(p=0.0290, 0.0472; $p.{\le}0.05$). The 1-year mortality index, length of stay and cost of the total hip arthroplasty patients which was obtained utilizing CCI have a limitative prediction power and therefore should be carefully analyzed for use.

• Health Policy and Management
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• v.19 no.4
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• pp.18-32
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• 2009

The goal of this study was to predict the health outcomes of lung cancer surgery based on the Charlson comorbidity index (CCI). An attempt was likewise made to assess the prognostic value of such data for predicting mortality, survival rate, and length of hospital stay. A medical-record review of 389 patients with non-small-cell lung cancer was performed. To evaluate the agreement, the kappa coefficient was tested. Logistic-regression analysis was also conducted within two years after the surgery to determine the association of CCI with death. Survival and multiple-regression analyses were used to evaluate the relationship between CCI and the hospital care outcomes within two-year survival after lung cancer surgery and the length of hospital stay. The results of the study showed that CCI is a valid prognostic indicator of two-year mortality and length of hospital stay, and that it shows the health outcomes, such as death, survival rate, and length of hospital stay, after the surgery, thus enabling the development and application of the methodology using a systematic and objective scale for the results.