Development and validation of interpretable machine learning models for inpatient fall events and electronic medical record integration.

OBJECTIVE: Falls are one of the most frequently occurring adverse events among hospitalized patients. The Morse Fall Scale, which has been widely used for fall risk assessment, has the two limitations of low specificity and difficulty in practical implementation. The aim of this study was to develop and validate an interpretable machine learning model for prediction of falls to be integrated in an electronic medical record (EMR) system. METHODS: This was a retrospective study involving a tertiary teaching hospital in Seoul, Korea. Based on the literature, 83 known predictors were grouped into seven categories. Interpretable fall event prediction models were developed using multiple machine learning models including gradient boosting and Shapley values. RESULTS: Overall, 191,778 cases with 272 fall events (0.1%) were included in the analysis. With the validation cohort of 2020, the area under the receiver operating curve (AUROC) of the gradient boosting model was 0.817 (95% confidence interval [CI], 0.720-0.904), better performance than random forest (AUROC, 0.801; 95% CI, 0.708-0.890), logistic regression (AUROC, 0.802; 95% CI, 0.721-0.878), artificial neural net (AUROC, 0.736; 95% CI, 0.650-0.821), and conventional Morse fall score (AUROC, 0.652; 95% CI, 0.570-0.715). The model's interpretability was enhanced at both the population and patient levels. The algorithm was later integrated into the current EMR system. CONCLUSION: We developed an interpretable machine learning prediction model for inpatient fall events using EMR integration formats.

The effect of continuity of care on the incidence of end-stage renal disease in patients with newly detected type 2 diabetic nephropathy: a retrospective cohort study.

BACKGROUND: Diabetic nephropathy requires periodic monitoring, dietary modification, and early intervention to prevent the disease severity within limited resource settings. To emphasize the importance of continuous care for chronic diseases, various studies have focused on the association between continuity of care (COC) and common adverse outcomes. However, studies aimed at understanding the effect of COC on the incidence of chronic diseases, such as end-stage renal disease (ESRD), are few. The aim of this study was to determine whether there is an association between COC and the incidence of ESRD among patients with diabetic nephropathy. Moreover, we identified individual- and hospital-level factors associated with the incidence of ESRD among diabetic nephropathy patients. METHODS: We conducted a retrospective cohort study using the administrative National Health Insurance claims data from 2005 to 2012 in the Republic of Korea. The dependent variable, a binary variable, was the incidence of ESRD due to diabetic renal complication. In addition, using the COC index as a binary variable with a cutoff point of 0.75, we divided patients into a 'Good COC group' (COC index≥0.75) and a 'Bad COC group' (COC index< 0.75). The survival analysis was performed using the Cox proportional hazards models. RESULTS: Among 3565 diabetic renal complication patients, ESRD occurred among 83 diabetes mellitus patients (2.3%). Nephropathy patients with lower COC level (< 0.75) had 1.99 times higher risk of ESRD incidence (95% confidence interval [CI]:1.27-3.12). In addition, the lowest income level patients had higher hazard ratio (HR) of ESRD than the highest income level patients (HR: 1.69 95% CI: 0.95-2.98), while patients with disabilities had 2.70 higher HR of ESRD than patients without disabilities (95% CI: 0.64-43). CONCLUSIONS: Among patients with diabetic renal complication, higher continuity of care was associated with lower risk of ESRD. It is therefore recommended that continuous follow-up be encouraged to prevent ESRD among diabetic renal complication patients. Moreover, disparities in health outcomes between socially vulnerable groups including patients with disabilities and those in the lowest income level should be addressed.

Changes in prescription pattern, pharmaceutical expenditure and quality of care after introduction of reimbursement restriction in diabetes in Korea.

Background: To ensure effective prescription practices and reduce diabetes-related pharmaceutical expenditures, Korea adopted a clinical practice guideline for the reimbursement system. Health care providers cannot receive reimbursement from National Health Insurance(NHI) unless it is for an appropriate prescription under the predefined clinical condition. The aim of this study was to evaluate prescription patterns in oral hypoglycemic agents, costs and effects on patient care since the introduction of the diabetes reimbursement restriction. Methods: We used claim data from 2008 to 2013, which included 26 315 diabetes patients and 9907 hospitals. An interrupted time series study design using generalized estimating equations was used to evaluate changes in patterns of single and combination therapy, brand name drug prescriptions, cost and hospital admission following the reimbursement restriction. Results: Following reimbursement restriction initiation, we found a statistically significant decrease in the average prescription rate of brand name drugs (-6.2%), whereas single therapy prescription increased (9.9%). There was also a reduction in trend change in the monthly prescription rate for combination therapy (-1.7%) and brand name drugs (-0.8%). For single therapy, the trend change in prescription rate increased after the intervention (0.8%). A reduction of trend change in pharmaceutical costs (-0.3%) was observed. However, we did not find a significant change in hospital admission for diabetes. Conclusions: Reimbursement restriction affects both pharmaceutical costs and physicians' decisions to prescribe oral hypoglycemic agents. We did not observe a significant reduction in quality of care following the intervention. Collectively, these findings indicate that reimbursement restriction has improved effective drug utilization and decreased health expenditures.

Hospital characteristics related to the hospital length of stay among inpatients receiving invasive cervical discectomy due to road traffic accidents under automobile insurance in South Korea.

BACKGROUND: In South Korea, people injured in road traffic accidents receive compensation for medical costs through their automobile insurance. However, the automobile insurance system appears to manage health care inefficiently. This study aimed to investigate the factors associated with the hospital length of stay (LOS), which was used as an indicator of healthcare utilization, for inpatients covered by automobile insurance and undergoing invasive cervical discectomy. METHODS: Insurance claims data from 158 hospitals were used. The study included 850 inpatients who were involved in automobile accidents in 2014 and 2015 and who underwent invasive cervical discectomy. Poisson regression analysis was performed to examine the associations between the LOS and hospital-level characteristics. RESULTS: The mean LOS for inpatients covered by automobile insurance was 25.75 days. A higher proportion of inpatients with automobile insurance were associated with a longer LOS (rate ratio [RR]: 1.027 per 1% increase, 95% confidence interval [CI]: 1.012-1.042). A higher hospital volume of invasive cervical discectomy (RR: 0.970 per 10 case increase, 95% CI: 0.945-0.997), bed turnover rate (RR: 0.988 per 1 increase, 95% CI: 0.979-0.997), and number of neurosurgeons or orthopedic specialists (RR: 0.930 per 1/100 beds increase, 95% CI: 0.876-0.987) were associated with a shorter LOS. CONCLUSIONS: Our findings suggest that inpatients covered by automobile insurance were associated with a longer LOS when treated at small-sized, low-provider, and low-volume hospitals with high proportions of such patients. Based on these findings, policymakers and healthcare professionals ought to consider improved strategies for efficient management of automobile insurance for inpatients in small-sized hospitals.

The effects of patient education on patient safety: can we change patient perceptions and attitudes?: Lessons from the Armed Forces Capital Hospital in Korea.

OBJECTIVE: Strategies to promote patient involvement in medical error prevention have been implemented, but little is known about the effects of education on changes in perceptions and attitudes about patients' own safety. DESIGN: We administered a survey to military personnel admitted to the Armed Forces Capital Hospital. Responses were classified according to perception and attitude. SETTING: Single military hospital in Korea. PARTICIPANTS: A total of 483 completed surveys were included in our study; 252 of the respondents received safety education at admission. METHODS: We provided educational program material to one-half of the patients at admission (intervention group). The other one-half of patients received no safety education (non-intervention group). We then performed two rounds of a self-administered survey, based on whether the patient received patient safety education. Cronbach's alpha was calculated to determine scale score reliability. Regression analysis was used to evaluate associations between education and change in scores. RESULTS: Scores for perception and attitude were greater in the intervention group. The results of the regression analysis revealed that compared with the non-intervention respondents, the respondents who received education had higher perception (estimate: 7.809, P < 0.0001) and attitude scores (estimate: 5.539, P < 0.0001). CONCLUSION: Our study results suggested that patient education was associated with higher scores in both perception and attitudes about safety. To improve patient engagement in this area, efficient methods that encourage patient empowerment should be developed. Specialized health care providers who provide patient level education are needed to achieve a satisfactory patient safety climate.

The differences in healthcare utilization for dental caries based on the implementation of water fluoridation in South Korea.

BACKGROUND: There were some debates about the water fluoridation program in South Korea, even if the program had generally substantial effectiveness. Because the out-of-pocket expenditures for dental care were higher in South Korea than in other countries, an efficient solution was needed. Therefore, we examined the relationship between the implementation of water fluoridation and the utilization of dental care. METHODS: We used the National Health Insurance Service National Sample Cohort. In this study, data finally included 472,250 patients who were newly diagnosed with dental caries during 2003-2013. We performed survival analysis using cox proportional hazard model, negative binomial-regression, and regression analyses using generalized estimating equation models. RESULTS: There were 48.49 % outpatient dental care visit during study period. Individuals with water fluoridation had a lower risk of dental care visits (HR = 0.949, 95 % CI = 0.928-0.971). Among the individuals who experienced a dental care visit, those with water fluoridation program had a lower number of dental care visits (ß = -0.029), and the period of water fluoridation had an inverse association with the dental care expenditures. CONCLUSION: The implementation of water fluoridation programs and these periods are associated with reducing the utilization of dental health care. Considering these positive impacts, healthcare professionals must consider preventive strategies for activating water fluoridation programs, such as changes in public perception and relations, for the effective management of dental care in South Korea.

Association between human resources and risk of hospitalisation in end-stage renal disease outpatients receiving haemodialysis: a longitudinal cohort study using claim data during 2013-2014.

OBJECTIVE: The number of patients requiring haemodialysis has gradually increased in South Korea. Owing to this growth, concerns have been raised regarding haemodialysis quality of care, and healthcare professionals must consider alternatives for appropriate management of patients with chronic kidney disease (CKD). Therefore, we investigated the association between risk of hospitalisation of outpatients who received haemodialysis due to end-stage renal disease (ESRD) and the human resources of the haemodialysis unit. SETTING: We used data from National Health Insurance (NHI) claims during October 2013 to September 2014. PARTICIPANTS: These data comprised 40 543 outpatients with ESRD (4 751 047 outpatient cases) who received haemodialysis. INTERVENTIONS: No interventions were made. OUTCOME MEASURE: We performed Poisson regression analysis using a generalised estimating equation that included both patient and haemodialysis unit characteristics to examine the factors associated with hospitalisation of outpatients with ESRD. RESULTS: Among 4 751 047 outpatient cases, 27 997 (0.59%) were hospitalised during the study period. A higher proportion of haemodialysis patient care specialists and a higher number of nurses experienced in haemodialysis were inversely associated with the risk of hospitalisation (per 10% increase in haemodialysis patient care specialists: relative risk (RR)=0.987, 95% CI 0.981 to 0.993; per 10-person increase in nurses who provided haemodialysis: RR=0.876, 95% CI 0.833 to 0.921). In addition, such associations were greater in severe patients. CONCLUSIONS: Our findings suggest that haemodialysis units with high-quality, haemodialysis-specialised human resources could positively affect the outcomes of outpatients with ESRD. Based on our findings, health policymakers and professionals should implement strategies for the optimal management of patients with CKD.

Association between reduction in copayment and gastric cancer patient concentration to the capital area in South Korea: NHI cohort 2003-2013.

Since 2004, the South Korean government has introduced a policy that decreases copayment for cancer patients by strengthening public coverage in the National Health Insurance (NHI) system (first phase=copayment for outpatient care from 30% to 20%; second phase=copayment for total medical expenditures from 20% to 10%; third phase=copayment for total medical expenditures from 10% to 5%). We aimed to investigate the relationship between the policy introduction and patient visits to hospitals in the capital area. We used data from the NHI Cohort 2003-2013, which included all medical claims (7193 cases) filed for 2124 patients who visited the hospital due to stomach cancer, and performed a segmented Poisson regression analysis. Of all hospital visits, 40.6% of patients were from the capital area. After the introduction of the second phase of the policy, there was an increase in patient concentration in the capital area, although there were no significant effects on patient concentration during the first and third phases of the policy. In conclusion, our findings suggest that the introduction of a policy that reduces copayment for cancer patients had a substantial impact on patient concentration in the capital area. Therefore, health policymakers should consider effective alternatives including efficient allocation of medical resources or support for the more vulnerable population as flexible benefit plans to aid healthcare utilization by cancer patients.

Medical care expenditure in suicides from non-illness-related causes.

OBJECTIVES: Several epidemiological studies on medical care utilization prior to suicide have considered the motivation of suicide, but focused on the influence of physical illnesses. Medical care expenditure in suicide completers with non-illness-related causes has not been investigated. METHODS: Suicides motivated by non-illness-related factors were identified using the investigator's note from the National Police Agency, which was then linked to the Health Insurance Review and Assessment data. We investigated the medical care expenditures of cases one year prior to committing suicide and conducted a case-control study using conditional logistic regression analysis after adjusting for age, gender, area of residence, and socioeconomic status. RESULTS: Among the 4515 suicides motivated by non-illness-related causes, medical care expenditures increased in only the last 3 months prior to suicide in the adolescent group. In the younger group, the proportion of total medical expenditure for external injuries was higher than that in the older groups. Conditional logistic regression analysis showed significant associations with being a suicide completer and having a rural residence, low socioeconomic status, and high medical care expenditure. After stratification into the four age groups, a significant positive association with medical care expenditures and being a suicide completer was found in the adolescent and young adult groups, but no significant results were found in the elderly groups for both men and women. CONCLUSIONS: Younger adults who committed suicide motivated by non-illness-related causes had a higher proportion of external injuries and more medical care expenditures than their controls did. This reinforces the notion that suicide prevention strategies for young people with suicidal risk factors are needed.

Medical care utilization during 1 year prior to death in suicides motivated by physical illnesses.

OBJECTIVES: Many epidemiological studies have suggested that a variety of medical illnesses are associated with suicide. Investigating the time-varying pattern of medical care utilization prior to death in suicides motivated by physical illnesses would be helpful for developing suicide prevention programs for patients with physical illnesses. METHODS: Suicides motivated by physical illnesses were identified by the investigator's note from the National Police Agency, which was linked to the data from the Health Insurance Review and Assessment. We investigated the time-varying patterns of medical care utilization during 1 year prior to suicide using repeated-measures data analysis after adjustment for age, gender, area of residence, and socioeconomic status. RESULTS: Among 1994 suicides for physical illness, 1893 (94.9%) suicides contacted any medical care services and 445 (22.3%) suicides contacted mental health care during 1 year prior to suicide. The number of medical care visits and individual medical expenditures increased as the date of suicide approached (p<0.001). The number of medical care visits for psychiatric disorders prior to suicide significantly increased only in 40- to 64-year-old men (p=0.002), women <40 years old (p=0.011) and women 40 to 64 years old (p=0.021) after adjustment for residence, socioeconomic status, and morbidity. CONCLUSIONS: Most of the suicides motivated by physical illnesses contacted medical care during 1 year prior to suicide, but many of them did not undergo psychiatric evaluation. This underscores the need for programs to provide psychosocial support to patients with physical illnesses.

Age and gender differences in medical care utilization prior to suicide.

BACKGROUND: Analysis of temporal patterns of medical care utilization prior to suicide may aid in developing suicide prevention programs. The aim of this study was to investigate age and gender differences in temporal patterns of medical care utilization during 1 year prior to suicide. METHODS: Medical care utilization data of all suicide completers in the Republic of Korea whose death occurred in 2004 (7903 men and 3620 women) was used. Differences among the quarters in medical expenditures and number of medical care visits were analyzed using a repeated measures analysis. Total medical expenditures were compared to those of age- and gender-matched controls by multiple logistic regression analysis. RESULTS: Among suicides, 84% (81% in men, 91% in women) contacted medical care in the year prior to suicide. In 10-39 year-old women, the number of medical care visits for gastrointestinal disease increased significantly during the final 3 months prior to suicide. All suicide completers showed that the number of medical care visits for psychiatric disorders increased significantly during the final 3 months with the exception of 10-19 year age group. Total medical expenditures during the year prior to suicide were elevated significantly and associated significantly with suicide risk (OR, 1.20; 95% CI, 1.19-1.21). LIMITATIONS: Inaccuracies in the underlying disease and death statistics data may have led to misclassification bias. CONCLUSIONS: Medical care utilization increased as the date of suicide approached. There are age and gender differences in medical care utilization in the year prior to suicide.

The risk of hospitalisation for infectious pneumonia in mineral dust exposed industries.

OBJECTIVES: The purpose of the study was to elucidate the relationship between industries characterised by mineral dust exposure and infectious pneumonia. METHODS: The authors applied a retrospective record linkage design and used the nationwide specific health examination database and identified industries where mineral dust exposure occurs and a control group composed of workers who had been exposed to noise-only during a 2000-2004 period. The database was matched with National Health Insurance claim records to identify pneumonia admissions from 2000 to 2005. The indirectly standardised admission ratios (SARs) for pneumonia admissions were estimated by comparing mineral dust exposed industry workers with noise-only exposed workers. RESULTS: The authors found significantly elevated SARs in both men (1.54, 95% CI 1.13 to 2.05) and women (3.23, 95% CI 1.40 to 6.37) working in the cement, lime, plaster and plaster products industries, and only in men working in the cast-metals industry (foundry) (1.64, 95% CI 1.25 to 2.11). CONCLUSIONS: These results support the association between mineral dust exposure, as well as metal fumes, and infectious pneumonia.

Ambient particulate matter as a risk factor for suicide.

OBJECTIVE: The authors assessed the relationship between exposure to ambient particulate matter and suicide in urban settings during a 1-year period. METHOD: The association between particulate matter and suicide was determined using a time-stratified case-crossover approach in which subjects served as their own controls. All suicide cases (4,341) in 2004 that occurred in seven cities in the Republic of Korea were included. Hourly mean concentrations of particulate matter < or =10 microm in aerodynamic diameter (at 106 sites in the seven cities) and particulate matter < or =2.5 microm in aerodynamic diameter (at 13 sites in one city) were measured. The percent increase in suicide risk associated with an interquartile range increase in particulate matter was determined by conditional logistic regression analysis after adjusting for national holidays and meteorological factors. Subgroup analysis was performed after stratification by underlying disease (cardiovascular disease, diabetes mellitus, chronic obstructive pulmonary disease, cancer, and psychiatric illness). RESULTS: The largest associations were a 9.0% increase (95% CI=2.4-16.1) and a 10.1% (95% CI=2.0-19.0) increase in suicide risk related to an interquartile range increase in particulate matter < or =10 microm (average of 0 to 2 days prior to the day of suicide) and particulate matter < or =2.5 microm (1 day prior to the day of suicide), respectively. Among individuals with cardiovascular disease, a significant association between particulate matter < or =10 microm (average of 0 to 2 days prior to the day of suicide) and suicide was observed (18.9%; 95% CI=3.2-37.0). CONCLUSIONS: Conclusions: A transient increase in particulate matter was associated with increased suicide risk, especially for individuals with preexisting cardiovascular disease.

Recurrence rate of vivax malaria in the Republic of Korea.

In the Republic of Korea (ROK), military antimalarial chemoprophylaxis was initiated in 1997. Although chemoprophylaxis reduces malaria cases, long-term chemoprophylaxis could increase resistance. In this study, the recurrence rate of vivax malaria was investigated. All vivax malaria cases that occurred before 31 December 2003 among soldiers and veterans who entered the ROK army between 1 January 1998 and 28 February 2001 were reviewed. Of the 3881 reported cases (2375 soldiers and 1506 veterans), 62 (1.6%) experienced a second attack and 2 (0.05%) experienced a third attack. Fifteen cases (24.2%) recurred < or =60 days and 43 cases (69.4%) recurred >180 days after the start of initial treatment. Most of the second attacks (54/62) were exposed to malaria risk after initial treatment. Among 1506 veterans, 5 (0.3%) recurred and they had not been exposed to malaria risk after retirement; 1 recurred 43 days and 4 recurred >180 days after the start of initial treatment. All recurring cases were completely cured using the same dosage and regimen used for the first or second treatments. In conclusion, few cases of vivax malaria recurred after standard treatment. It is suggested that recurrences of vivax malaria are effectively prevented by the current treatment regimen and dosage.

[Effect of sociodemographic factors, cancer, psychiatric disorder on suicide: gender and age-specific patterns].

OBJECTIVES: We examined the effect of sociodemographic factors, cancer, and psychiatric disorders on suicide by gender and age-specific patterns in South Korea. METHODS: The study is a case-control study. Claim data was obtained from the national health insurance database and national death registration database. The number of people who committed suicide was 11,523, which was matched with a control group consisting of ten times as many people at 115,230 selected from the national health insurance and medical aids beneficiaries. The medical utilization of the case group was one year before death and that of the control group was from July 1,2003 to June 30, 2004. Four variables-address, economic status, presence of a psychiatric disease, and cancer-were used in multiple logistic regression analyses. RESULTS: Living in cities or in rural areas showed a greater risk for suicide than living in a metropolitan city. Low economic status, the presence of a psychiatric disorder, and cancer were also statistically meaningful risk factors for suicide. The three major psychiatric diseases, schizophrenia, alcohol abuse, and bipolar disorder, were meaningful in all age groups, but the scale of the odds ratio differed by the age group. Only the psychiatric disorder variable was meaningful in the adolescent group, whereas a psychiatric disorder and economic status were meaningful for the young adult group, and all variables were meaningful for the middle-aged group. A psychiatric disorder and cancer were meaningful in the elderly group, economic status was meaningful for male subjects, and address was meaningful for female subjects. CONCLUSIONS: Factors such as living in city or rural areas, low economic status, the presence of a psychiatric disorder, and cancer were statistically meaningful risk factors in suicide. These factors also differed by age group. Therefore, policymakers should establish policies for suicide prevention that are relevant for each age group.

Protective effectiveness of hantavirus vaccine.

A case-control study in the Republic of Korea evaluated the protective effectiveness of the hantavirus vaccine. Point estimates showed increasing effectiveness with increasing numbers of doses received: 25% for one dose, 46% for two doses, and 75% for three doses. All 95% confidence intervals overlapped zero; therefore, the findings could be due to chance.