Impact of linkage level on inferences from big data analyses in health and medical research: an empirical study.

BACKGROUND: Linkage errors that occur according to linkage levels can adversely affect the accuracy and reliability of analysis results. This study aimed to identify the differences in results according to personally identifiable information linkage level, sample size, and analysis methods through empirical analysis. METHODS: The difference between the results of linkage in directly identifiable information (DII) and indirectly identifiable information (III) linkage levels was set as III linkage based on name, date of birth, and sex and DII linkage based on resident registration number. The datasets linked at each level were named as databaseIII (DBIII) and databaseDII (DBDII), respectively. Considering the analysis results of the DII-linked dataset as the gold standard, descriptive statistics, group comparison, incidence estimation, treatment effect, and moderation effect analysis results were assessed. RESULTS: The linkage rates for DBDII and DBIII were 71.1% and 99.7%, respectively. Regarding descriptive statistics and group comparison analysis, the difference in effect in most cases was "none" to "very little." With respect to cervical cancer that had a relatively small sample size, analysis of DBIII resulted in an underestimation of the incidence in the control group and an overestimation of the incidence in the treatment group (hazard ratio [HR] = 2.62 [95% confidence interval (CI): 1.63-4.23] in DBIII vs. 1.80 [95% CI: 1.18-2.73] in DBDII). Regarding prostate cancer, there was a conflicting tendency with the treatment effect being over or underestimated according to the surveillance, epidemiology, and end results summary staging (HR = 2.27 [95% CI: 1.91-2.70] in DBIII vs. 1.92 [95% CI: 1.70-2.17] in DBDII for the localized stage; HR = 1.80 [95% CI: 1.37-2.36] in DBIII vs. 2.05 [95% CI: 1.67-2.52] in DBDII for the regional stage). CONCLUSIONS: To prevent distortion of the analyses results in health and medical research, it is important to check that the patient population and sample size by each factor of interest (FOI) are sufficient when different data are linked using DBDII. In cases involving a rare disease or with a small sample size for FOI, there is a high likelihood that a DII linkage is unavoidable.

Effect of Chronic Kidney Disease on All-Cause Mortality After Hip Fracture Surgery: A Retrospective Cohort Study.

In this retrospective cohort study, we investigated: (1) The impact of comorbid chronic kidney disease (CKD) on postoperative mortality in patients with a hip fracture; (2) mortality variations by dialysis type, potentially indicating CKD stage; (3) the efficacy of different hip fracture surgical methods in reducing mortality for patients with CKD. This study included 25,760 patients from the Korean National Health Insurance Service-Senior cohort (2002-2019) who underwent hip fracture surgery. Participants were categorized as CKD and Non-CKD. Mortality rate was determined using a generalized linear model with a Poisson distribution. The effect size was presented as a hazard ratio (HR) through a Cox proportional-hazard model. During follow-up, we ascertained that 978 patients (3.8%) had CKD preoperatively. Compared to the Non-CKD group, the mortality risk (HR) in the CKD group was 2.17 times higher (95% confidence interval [CI], 1.99-2.37). In sensitivity analysis, the mortality risk of in patients who received peritoneal dialysis and hemodialysis was 6.21 (95% CI, 3.90-9.87) and 3.62 times (95% CI, 3.11-4.20) higher than that of patients who received conservative care. Mortality risk varied by surgical method: hip hemiarthroplasty (HR, 2.11; 95% CI, 1.86-2.40), open reduction and internal fixation (HR, 2.21; 95% CI, 1.94-2.51), total hip replacement (HR, 2.27; 95% CI, 1.60-3.24), and closed reduction and percutaneous fixation (HR, 3.08; 95% CI, 1.88-5.06). Older patients with CKD undergoing hip fracture surgery had elevated mortality risk, necessitating comprehensive pre- and postoperative assessments and management.

Comparative Interrupted Time Series Analysis of Medical Expenses in Patients with Intertrochanteric Fracture Who Underwent Internal Fixation and Hemiarthroplasty.

Purpose: The objective of this study was to assess postoperative direct medical expenses and medical utilization of elderly patients who underwent either hemiarthroplasty (HA) or internal fixation (IF) for treatment of a femoral intertrochanteric fracture and to analyze differences according to surgical methods and age groups. Materials and Methods: Data from the 2011 to 2018 Korean National Health Insurance Review & Assessment Service database were used. Risk-set matching was performed for selection of controls representing patients with the same sex, age, and year of surgery. A comparative interrupted time series analysis was performed for evaluation of differences in medical expenses and utilization between the two groups. Results: A total of 10,405 patients who underwent IF surgery and 10,405 control patients who underwent HA surgery were included. Medical expenses were 18% lower in the IF group compared to the HA group during the first year after the fracture (difference-in-difference [DID] estimate ratio 0.82, 95% confidence interval [CI] 0.77-0.87, P<0.001), and 9% lower in the second year (DID estimate ratio 0.91, 95% CI 0.85-0.99, P=0.018). Length of hospital stay was significantly shorter in the IF group compared to the HA group during the first two years after time zero in the age ≥80 group. Conclusion: A noticeable increase in medical expenses was observed for patients who underwent HA for treatment of intertrochanteric fractures compared to those who underwent IF over a two-year period after surgery. Therefore, consideration of such findings is critical when designing healthcare policy support for management of intertrochanteric fractures.

Comparative Interrupted Time Series Analysis of Direct Medical Expense and Length of Stay in Elderly Patients with Femoral Neck Fractures Who Underwent Total Hip Arthroplasty and Hemiarthroplasty: A Real World Nationwide Database Study.

Background: The objective of our study was to analyze the postoperative direct medical expenses and hospital lengths of stay (LOS) of elderly patients who had undergone either hemiarthroplasty (HA) or total hip arthroplasty (THA) for femoral neck fractures and to determine the indication of THA by comparing those variables between the 2 groups by time. Methods: In this comparative large-sample cohort study, we analyzed data from the 2011 to 2018 Korean National Health Insurance Review and Assessment Service database. The included patients were defined as elderly individuals aged 60 years or older who underwent HA or THA for a femoral neck fracture. A 1:1 risk-set matching was performed on the propensity score, using a nearest-neighbor matching algorithm with a maximum caliper of 0.01 of the hazard components. In comparative interrupted time series analysis, time series were constructed using the time unit of one-quarter before and after 3 years from time zero. For the segmented regression analysis, we utilized a generalized linear model with a gamma distribution and logarithmic link function. Results: A total of 4,246 patients who received THA were matched and included with 4,246 control patients who underwent HA. Although there was no statistically significant difference in direct medical expense and hospital LOS for the first 6 months after surgery, direct medical expenses and hospital LOS in THA were relatively reduced compared to the HA up to 24 months after surgery (p < 0.05). In the subgroup analysis, the THA group's hospital LOS decreased significantly compared to that of the HA group during the 7 to 36 months postoperative period in the 65 ≤ age < 80 age group (p < 0.05). Direct medical expenses of the THA group significantly decreased compared to those of the HA group during the period from 7 to 24 months after surgery in the men group (p < 0.05). Conclusions: When performing THA in elderly patients with femoral neck fractures, the possibility of survival for at least 2 years should be considered from the perspective of medical expense and medical utilization. Additionally, in healthy and active male femoral neck fracture patients under the age of 80 years, THA may be more recommended than HA.

Differences in end-of-life care patterns between types of hospice used for cancer patients: a retrospective cohort study.

BACKGROUND: In response to the rapid aging population and increasing number of cancer patients, discussions on dignified end-of-life (EoL) decisions are active around the world. Therefore, this study aimed to identify the differences in EoL care patterns between types of hospice used for cancer patients. METHODS: In this population-based cohort study, the Korean National Health Insurance Service cohort data containing all registered cancer patients who died between 2017 and 2021 were used. A total of 408,964 individuals were eligible for analysis. The variable of interest, the type of hospice used in the 6 months before death, was classified as follows: (1) Non-hospice users; (2) Hospital-based hospice single users; (3) Home-based hospice single users; (4) Combined hospice users. The outcomes were set as patterns of care, including intense care and supportive care. To identify differences in care patterns between hospice types, a generalized linear model with zero-inflated negative binomial distribution was applied. RESULTS: Hospice enrollment was associated with less intense care and more supportive care near death. Notably, those who used combined hospice care had the lowest probability and frequency of receiving intense care (aOR: 0.18, 95% CI: 0.17-0.19, aRR: 0.47, 95% CI: 0.44-0.49), while home-based hospice single users had the highest probability and frequency of receiving supportive care (Prescription for narcotic analgesics, aOR: 2.95, 95% CI: 2.69-3.23, aRR: 1.45, 95% CI: 1.41-1.49; Mental health care, aOR: 3.40, 95% CI: 3.13-3.69, aRR: 1.35, 95% CI: 1.31-1.39). CONCLUSION: Our findings suggest that although intense care for life-sustaining decreases with hospice enrollment, QoL at the EoL actually improves with appropriate supportive care. This study is meaningful in that it not only offers valuable insight into hospice care for terminally ill patients, but also provides policy implications for the introduction of patient-centered community-based hospice services.

Trends in private caregiving cost after implementing a comprehensive nursing service covered by national health insurance: Interrupted time series.

BACKGROUND: The Korean government has implemented a comprehensive nursing care service system (CNS) to mitigate the stress faced by caregivers. OBJECTIVE: This study aimed to assess trends in the estimated average costs of private caregiving and determine the difference in costs between those using CNS and those not using it. DESIGN: A comparative interrupted time series analysis with a 2-year lag period verified total private caregiving cost trends; biannual differences in costs were evaluated based on using CNS. PARTICIPANTS: The main unit of analysis was episode. We extracted a total of 6418 episodes of hospitalization in acute care settings that included the use of caregiving services (formal, informal caregiving and CNS). METHODS: We conducted segmented regression to assess the impact of CNS on total private caregiving costs using data from 2012 to 2018, excluding the years 2015 and 2016 of the Korean Health Panel dataset. RESULTS: We presented that the immediate mean difference in total private caregiving costs between CNS users and non-users was -444.7 USD two years after the implementation of the CNS policy (95 % CI -714.5 to -174.5, p-value 0.001). Among individuals living in rural areas, two years after the implementation of the CNS policy, there was a significant immediate mean cost difference of -476.9 USD in total private caregiving costs between CNS users and non-users (p-value 0.011). Similarly, for episodes with a Charlson Comorbidity Index (CCI) score of 0 to 1, there was a substantial immediate mean cost difference in total private caregiving costs between CNS users and non-users, amounting to -399.9 USD two years after the CNS policy (p-value 0.008). CONCLUSIONS: This study evaluated the trend of total private caregiving costs between groups using and not using CNS. After two years of being covered by CNS health insurance, those who utilized CNS paid $433 less for their total private caregiving cost over a 6-month period, compared to those who did not use CNS. The adoption of CNS may be an effective system for relieving the financial burden on inpatients in need of private caregiving services. TWEETABLE ABSTRACT: Korean Comprehensive Nursing Service reduces private caregiving costs.

Association between nurse staffing level in intensive care settings and hospital-acquired pneumonia among surgery patients: result from the Korea National Health Insurance cohort.

This study examined the association between the number of nursing staff in intensive care units (ICUs) and hospital-acquired pneumonia (HAP) among surgical patients in South Korea. Data were obtained between 2008 and 2019 from the Korean National Health Insurance Service Cohort Database; 37,706 surgical patients who received critical care services were included in the analysis. Patients with a history of pneumonia 1 year prior to surgery or those who had undergone lung-related surgery were excluded. The ICU nursing management fee is an admission fee that varies based on the grading determined by nurse-to-bed ratio. Using this grading system, we classified four groups from the highest to the lowest level based on the proportion of beds to nurses (high, high-mid, mid-low, and low group). HAP was defined by the International Classification of Disease, 10th revision (ICD-10) code. Multilevel logistic regression was used to investigate the relationship between the level of ICU nurse staffing and pneumonia, controlling for variables at the individual and hospital levels. Lower levels of nurse staffing were associated with a greater incidence of HAP than higher levels of nurse staffing (mid-high, OR: 1.33, 95% CI: 1.12-1.57; mid-low, OR: 1.61, 95% CI: 1.27-2.04; low, OR: 2.13, 95% CI: 1.67-2.71). The intraclass correlation coefficient value was 0.177, and 17.7% of the variability in HAP was accounted for by the hospital. Higher ICU nursing management fee grades (grade 5 and above) in general and hospital settings were significantly associated with an increased risk of HAP compared to grade 1 admissions. Similarly, in tertiary hospitals, grade 2 and higher ICU nursing management fees were significantly associated with an increased risk of HAP compared to grade 1 admissions. Especially, a lower level of nurse staffing was associated with bacterial pneumonia but not pneumonia due to aspiration. In conclusion, this study found an association between the level of ICU nurse staffing and HAP among surgical patients. A lower level of nurse staffing in the ICU was associated with increased rates of HAP among surgical patients. This indicates that having fewer beds assigned to nurses in the ICU setting is a significant factor in preventing HAP, regardless of the size of the hospital.

Analysis of Long-Term Medical Expenses in Vertebral Fracture Patients.

Background: The objective of this study was to analyze the direct medical expenses of a vertebral fracture cohort (VC) and a matched cohort (MC) over 5 years preceding and following the fracture, analyze the duration of the rise in medical expenses due to the fracture, and examine whether the expenses vary with age group, utilizing a national claims database. Methods: Subjects with vertebral fractures and matched subjects were chosen from the National Health Insurance Service Sample cohort (NHIS-Sample) of South Korea. Patients with vertebral fractures were either primarily admitted to acute care hospitals (index admissions) or those who received kyphoplasty or vertebroplasty during the follow-up period (2002-2015). A risk-set matching was performed using 1 : 5 random sampling to simulate a real-world situation. Individual-level direct medical expenses per quarter were calculated for 5 years prior and subsequent to the vertebral fracture. In this analysis using a comparative interrupted time series design, we examined the direct medical expenses of a VC and an MC. Results: A total of 3,923 incident vertebral fracture patients and 19,615 matched subjects were included in this study. The mean age was 75.5 ± 7.4 years, and 69.5% were women. The mean difference in medical expenses between the two groups increased steadily before the fracture. The medical expenses of the VC peaked in the first quarter following the fracture. The cost changes were 1.82 times higher for the VC than for the MC (95% confidence interval, 1.62-2.04; p < 0.001) in the first year. Subsequently, there were no differential changes in medical expenses between the two groups (p > 0.05). In the < 70-year subgroup, there were no differential changes in medical expenses between the two groups (p > 0.05). However, in the ≥ 80-year subgroup, the cost changes for the VC were higher than those for the MC up to 5 years after time zero. Conclusions: Based on our study results, we suggest that health and medical policies for vertebral fractures should be designed to last up to approximately 1 year after the fracture. Health policies should be differentiated according to age group.

Changes in the Place of Death of Patients With Cancer After the Introduction of Insurance-Covered, Home-Based Hospice Care in Korea.

Importance: Although hospice care has been covered by health insurance for the purpose of improving the quality of life of patients with terminal cancer as well as their caregivers, few studies have evaluated the outcomes of the policy to cover home-based hospice care services. Objective: To investigate the changes in the place of death of patients with cancer after the introduction of insurance-covered, home-based hospice care services in Korea. Design, Setting, and Participants: This cohort study used data from February 1, 2018, to December 31, 2021, from the Causes of Death Statistics database, released annually by Statistics Korea, which contains information on all deaths in the country. Individuals who died of cancer, a representative hospice-eligible disease, were assigned to the case group, and those who died of dementia, a non-hospice-eligible disease, were assigned to the control group. A total of 218 522 individuals constituted the study population. Exposure: Because the Korean Health Insurance Service had begun covering home-based hospice care services on September 1, 2020, and the last follow-up date was December 31, 2021, the follow-up periods for before and after intervention were 31 months and 16 months, respectively (preintervention period: February 1, 2018, to August 31, 2020; postintervention period: September 1, 2020 to December 31, 2021). Main Outcomes and Measures: The place of death was categorized as a binary variable according to whether it was the person's own home or not. Comparative interrupted time-series models with segmented regression were applied to analyze the time trend and its change in outcomes. Results: Of the 218 522 deaths eligible for the analysis (mean [SD] age at death, 78.6 [8.8] years; 130 435 men [59.7%]), 207 459 were due to cancer, and 11 063 were due to dementia. Immediately after the introduction of home-based hospice care, the rate of home deaths was 24.5% higher for patients with cancer than for those with dementia (estimate, 1.245 [95% CI, 1.030-1.504]; P = .02). The difference in the level change between cancer deaths and dementia deaths, on intervention, was more pronounced for those living in rural areas (estimate, 1.320 [95% CI, 1.118-1.558]; P = .001). In addition, a higher educational level was associated with a larger difference in the immediate effect size due to home-based hospice care (low educational level: estimate, 1.205 [95% CI, 1.025-1.416]; P = .02; middle educational level: estimate, 1.307 [95% CI, 0.987-1.730], P = .06; high educational level: estimate, 1.716 [95% CI, 0.932-3.159]; P = .08). Conclusions and Relevance: In this cohort study exploring the changes in the place of death for patients with cancer after the insurance mandates for home-based hospice care in Korea, the probability of patients with cancer dying in their own homes increased after the intervention. This finding suggests the need to broaden the extent of home-based hospice care to honor the autonomy of individuals with terminal illness and improve their quality of death.

Association between physical activity and health-related quality of life in middle-aged and elderly individuals with musculoskeletal disorders: Findings from a national cross-sectional study in Korea.

PURPOSE: This study aimed to identify the association between physical activity and health-related quality of life (HRQoL) in middle-aged and elderly individuals with musculoskeletal disorders. METHODS: This study used data from the 2016-2020 Korea National Health and Nutrition Examination Survey (KNHANES). We included only those over 40 years of age diagnosed with one or more of the following: osteoarthritis, rheumatism, and osteoporosis. In total, 4,731 participants (783 men and 3,948 women) were included as the study population. Multiple logistic regression analysis was performed to examine the association between physical activity and HRQoL. RESULTS: In the case of middle-aged and elderly individuals with musculoskeletal disorders, the likelihood of HRQoL worsening was significantly lower for those who regularly engaged in physical activity compared with that of those who did not engage in physical activity at all (men: OR 0.58, 95% CI 0.37-0.90; women: OR 0.64, 95% CI 0.53-0.79). Stratified analysis by the type and intensity of physical activity revealed that the possibility of poor HRQoL was lowest when leisure-related moderate-intensity physical activities were performed (men: OR 0.44, 95% CI 0.22-0.89; Women: OR 0.50, 95% CI 0.36-0.69). CONCLUSIONS: Our findings suggest that engaging in regular physical activity contributes to preventing exacerbation of HRQoL, even if the individual suffers from musculoskeletal disorders. It is necessary to provide an appropriate type and intensity of physical activity in consideration of the patients' pain and severity.

Association of behavior pattern with overweight and obesity in South Korean adults-A multi correspondence analysis (KNHANES-2018-2020).

The objective was to determine the association between health-related behaviour with overweight and obesity in South Korean adults by using the Korean National Health and Nutritional Examination Survey (KNHANES) 2018-2020. The study participants were 16,784 aged ≥ 20years. The variables were socio-demographic, lifestyle, food habits and metabolic conditions. The logistic regression analysis performed to find the association by the odds ratio (OR, 95% CI). MCA performed to identify risk factors were computed for overweight and obesity. Overweight and obesity were significantly associated with health behaviour, high income (OR = 1.26; 95% CI: 1.15-1.39), smoking(OR = 1.29; 95% CI: 1.08-1.53), low physical activity(OR = 3.23; 95% CI: 1.79-4.69), diabetes(OR = 2.70; 95% CI: 1.62-4.50), high cholesterol and low HDL(OR = 3.98; 95%CI:2.65-5.97). The high discriminant variables of MCA were aged over 60years, lower education, high income, diabetes, lack of physical activity, and high cholesterol. The findings confirm that the OR of obesity and overweight was likely associated with health behaviour patterns. Besides, it indicates the MCA would be very effective to identify the population-based data context than individual data and it may suggest that more research on association between health behaviours and obesity prevention interventions should be developed for each age group for better health outcomes.

Analysis of the effects of intraoperative warming devices on surgical site infection in elective hip arthroplasty using a large nationwide database.

INTRODUCTION: The aim of our study is to analyze the association of usage and type of warming device with the risk of surgical site infection (SSI) in patients who underwent hip arthroplasty, and to analyze the factors that increase the risk of SSI if the warming device is not used. MATERIALS AND METHODS: This retrospective cross-sectional study identified subjects from data of "Evaluation of the Appropriate Use of Prophylactic Antibiotics". Included patients were defined as those who underwent elective unilateral hip hemiarthroplasty or total hip arthroplasty (THA). Patients were classified into no intraoperative warming device, forced air warming devices, and devices using conduction. Multiple logistic regression analysis was conducted to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) to assess the association between warming devices and SSI. RESULTS: A total of 3945 patients met the inclusion criteria. Compared to those who received an intraoperative warming device, the odds of developing SSI were 1.9 times higher in those who did not receive intraoperative warming devices (aOR 1.9; 95% CI 1.1-3.6). The risk of SSI was 2.2 times higher with forced air warming devices compared to devices using conduction but this difference was not statistically significant (aOR 2.2; 95% CI 0.7-6.8). The risk of SSI increased in males (aOR 2.8; 95% CI 1.1-7.2), in patients under 70 years of age (aOR 4.4; 95% CI 1.6-10.4), in patients with a Charlson`s comorbidity index of 2 or higher (aOR 3.3; 95% CI 1.3-8.7), and in patients who underwent THA (aOR 3.8; 95% CI 1.7-8.3) when intraoperative warming devices were not used. CONCLUSIONS: The use of intraoperative active warming devices is highly recommended to prevent SSI during elective hip arthroplasty. In particular, male patients younger than 70 years, those with a high CCI, and those undergoing THA are at significantly increased risk of SSI if intraoperative active warming devices are not used. Intraoperative warming device using conduction is likely superior to forced air warming device, but further studies are needed to confirm this.

Factors related to the frequent use of emergency department services in Korea.

BACKGROUND: Frequent Emergency Department (ED) visitors are identified by the policymakers to reduce avoidable ED visits and lessen the financial and operational burden. This study aimed to identify the factors related to the frequent use of ED services. METHODS: This nationwide, cross-sectional observational study was conducted using information obtained from the 2019 National Emergency Department Information System (NEDIS) database. Frequent ED users were defined as patients with four or more ED visits a year. We performed multiple logistic regression analyses to verify the relationship among sociodemographic characteristics, residential characteristics, clinical characteristics, and frequency of ED visits. RESULTS: Among 4,063,640 selected patients, 137,608 patients visited the ED four or more times a year (total number of visits = 735,502 times), which accounted for 3.4% and 12.8% of the total number of ED users and ED visits, respectively. A high ED visit frequency was associated with male sex, age < 9 or ≥ 70 years, Medical Aid (based on the insurance type), lower number of medical institutions and beds compared with that of the national average, and conditions, such as cancer, diabetes, renal failure, and mental illness. A low ED-visit frequency was associated with residence in regions vulnerable to emergency medical care and regions with high income. The possibility of frequent ED visits was high for patients with level 5 severity (non-emergent) and those with an increased need for medical treatment, including older patients and patients with cancer or mental illness. The possibility of frequent ED visits was low for patients aged > 19 years with level 1 severity (resuscitation). CONCLUSIONS: Health service accessibility factors, including low income and medical resource imbalance, were associated with frequent ED visits. Future large-scale prospective cohort studies are warranted to establish an efficient emergency medical system.

Effect of dementia on all-cause mortality in hip fracture surgery: a retrospective study on a nationwide Korean cohort.

OBJECTIVES: We aimed to evaluate the effect of dementia on the 1-year all-cause mortality in elderly patients who underwent hip fracture surgery, using a nationwide cohort in Korea. DESIGN, SETTING, AND PARTICIPANTS: This was a nationwide, retrospective study. Elderly patients (≥60 years) with and without dementia who underwent hip fracture surgery between January 2005 and December 2012 were distinguished using the data from the Korean National Health Insurance Service-Senior cohort. INTERVENTIONS: None. PRIMARY AND SECONDARY OUTCOME MEASURES: The mortality rates with 95% CIs and the impact of dementia on all-cause mortality were calculated using a generalised linear model with Poisson distribution and a multivariable-adjusted Cox proportional hazards model, respectively. RESULTS: Among the 10 833 patients who underwent hip fracture surgery, 13.4% were diagnosed with dementia. During the 1-year follow-up period, 1586 patients with hip fracture without dementia died in 8356.5 person-years (incidence rate (IR)=189.2 per 1000 person-years, 95% CI 179.91 to 198.99), while 340 deaths were confirmed in patients with hip fracture with dementia in 1240.8 person-years (IR, 273.1 per 1000 person-years, 95% CI 244.94 to 304.58). Patients with hip fracture and dementia were 1.23 times more likely to die than those in the control group in the same period (HR=1.23, 95% CI 1.09 to 1.39). CONCLUSION: Dementia is a risk factor for 1-year all-cause mortality after hip fracture surgery. To improve the postoperative outcomes of patients with dementia who have undergone hip fracture surgery, effective treatment models such as multidisciplinary diagnosis and strategic rehabilitation should be established.

How Does Medical Policy on the Use of Prophylactic Antibiotics Affect Medical Costs, Length of Hospital Stay, and Antibiotic Use in Orthopedics?

PURPOSE: The purpose of this study was to compare patients who had undergone spine surgery (SS) and hip arthroplasty surgery (HAS) and to analyze how medical policies drawn from "The Evaluation of the Appropriate Use of Prophylactic Antibiotics" have affected length of hospital stay (LOS), direct medical costs (DMC), and the duration of antibiotics use in Korea. MATERIALS AND METHODS: This retrospective nationwide study identified subjects from the Korean National Health Insurance Review and Assessment Service database from January, 2011 to December, 2018. Evaluation of HAS (control group) was implemented in 2007, and that for SS (case group) was conducted for the first time in 2014 (intervention time). In our comparative interrupted time series analysis, we compared DMC, LOS, and use of antibiotics between both groups. RESULTS: 177468 patients who underwent SS and 89372 patients who underwent HAS were included in the study. In 2016, DMC increased for HAS, compared to SS, by 1.03 times (p=0.041). However, cost changes during other observational periods for SS were not higher than those for HAS (p>0.05). SS incurred a reduced LOS of 3% in the first 2 years (p<0.05). Thereafter, LOS changes in SS were not smaller than those in HAS. A decrease in the usage of total antibiotics and broad spectrum antibiotics was observed for 5 years. CONCLUSION: This medical policy was effective in terms of reducing usage and duration of antibiotics use, especially in the first 2 years after the implementation of the policy.

Association between smoking status and subjective quality of sleep in the South Korean population: a cross-sectional study.

PURPOSE: This study aimed to investigate the relationship between smoking and subjective sleep quality in the Korean adult population. METHODS: We designed a cross-sectional survey using data from the 2018 Korean Community Health Service Conditions Survey and selected smoking status as our variable of interest. We divided the participants into people who currently, never, and formerly smoked, those who smoked < 20 cigarettes/day, and those who smoked > 20 cigarettes/day. Subjective sleep quality was analyzed using the Pittsburgh Sleep Quality Index. Multiple logistic regression analysis was performed for statistical analysis. RESULTS: A total of 174,665 participants were enrolled. People who formerly and currently smoked were found to have poorer subjective sleep quality than those who never smoked. The odds of poor subjective sleep quality in people who smoked > 20 cigarettes/day were 1.15 times (95% confidence interval: 1.09-1.21) for men and 1.51 times (95% confidence interval: 1.22-1.86) for women, compared with men and women who never smoked. CONCLUSIONS: Smoking was negatively associated with subjective sleep quality. Smoking cessation programs and lifestyle improvement education may be justifiable to improve the quality of sleep in Korean adults.

The Prevalence of Clostridium difficile Colitis and Effect on All-Cause Mortality in Elderly Patients after Hip Fracture Surgery: A Korean Nationwide Cohort Study.

Background: This study aimed to investigate the prevalence of Clostridium difficile colitis (CDC) in elderly patients with hip fractures using a nationwide cohort database and to analyze the effect of CDC on the all-cause mortality rate after hip fracture. Methods: This retrospective nationwide study identified subjects from the Korean National Health Insurance Service-Senior cohort. The subjects of this study were patients who were over 65 years old and underwent surgical treatment for hip fractures from January 1, 2002, to December 31, 2015. The total number of patients included in this study was 10,158. The diagnostic code used in this study was A047 of the International Classification of Diseases, 10th revision for identifying CDC. Procedure codes for C. difficile culture or toxin assay were BY021 and BY022. CDC patients were defined as follows: patients treated with oral vancomycin or metronidazole over 10 days and patients with procedure codes BY021 and BY022 or diagnostic code A047 after hip fracture. Incidence date (index date, time zero) of hip fracture for analyzing risk of all-cause mortality was defined as the date of discharge. A generalized estimating equation model with Poisson distribution and logarithmic link function was used for estimating adjusted risk ratios and 95% confidence intervals to assess the association between CDC and cumulative mortality risk. Results: The prevalence of CDC during the hospitalization period in the elderly patients with hip fractures was 1.43%. Compared to the non-CDC group, the CDC group had a 2.57-fold risk of 30-day mortality after discharge, and a 1.50-fold risk of 1-year mortality after discharge (p < 0.05). Conclusions: The prevalence of CDC after hip fracture surgery in elderly patients was 1.43%. CDC after hip fracture in the elderly patients significantly increased the all-cause mortality rate after discharge.

Association of the "Weekend Warrior" and Other Physical Activity Patterns with Metabolic Syndrome in the South Korean Population.

These days, it is not common for people to have time to do physical activities regularly because of their own work. So, they perform physical activities all at once, which is often called the "weekend warrior". Therefore, this study aimed to examine the association of the "weekend warrior" and other physical activity patterns with metabolic syndrome. Data from the Korea National Health and Nutrition Examination Survey were used, and 27,788 participants were included. The participants were divided into inactive, weekend warriors, and regularly active based on physical activity patterns. The risk of metabolic syndrome in each group was analyzed using multiple logistic regression. The inactive and weekend warrior groups showed a higher likelihood of developing metabolic syndrome than the regularly active groups (weekend warrior: odds ratio (OR) 1.29, confidence interval (CI) 1.02-1.65; inactive: OR 1.38, CI 1.25-1.53). According to the physical activity patterns, the weekend warrior group showed a dose-response relationship compared to the regularly active group (only moderate: OR 1.85, CI 1.25-2.72; only vigorous: OR 1.41, CI 0.93-2.14; both: OR 0.84, CI 0.56-1.27). This study found increasing the amount of physical activity and performing vigorous-intensity physical activity helped manage metabolic syndrome in the weekend warrior group.

Nested Case Control Study on the Risk of Suicide Death in Elderly Patients with Pelvic Fractures Using a Nationwide Cohort.

Background: The aim of this study was to investigate the incidence rate of suicide deaths in elderly patients with pelvic fractures using a nationwide database and to analyze change in the risk of suicide death overtime after pelvic fractures compared to controls. Methods: We used the National Health Insurance Service-Senior cohort (NHIS-Senior) of South Korea. Cases and controls were matched for sex, age, history of hospital admission within 1 year, and presence of depression on the date of suicide death. Controls were collected by random selection at a 1 : 5 ratio from patients at risk of becoming cases when suicide cases were collected. Incident pelvic fractures were identified from the NHIS-Senior as follows: first admission during the observational period (2002-2015) to an acute care hospital with a diagnostic code of International Statistical Classification of Diseases and Related Health Problems, 10th revision S321, S322, S323, S324, S325, or S328 and age 65-99 years. Conditional logistic regression analysis was performed to evaluate the association between pelvic fractures and the risk of suicide death. Results: A total of 2,863 suicide cases and 14,315 controls were identified. Suicide case patients had been more frequently exposed to steroids (odds ratio [OR], 1.32; 95% confidence interval [CI], 1.21-1.45), benzodiazepines (OR, 1.76; 95% CI, 1.61-1.93), and non-steroidal anti-inflammatory drugs (OR, 1.18; 95% CI, 1.07-1.29). Pelvic fractures within 1 year from the date of suicide death were statistically significantly associated with increased risk of suicide (adjusted OR [AOR], 2.65; 95% CI, 1.29-5.45; p = 0.008) compared to controls. The risk of suicide death declined as the incidence date of pelvic fracture was more remote from the date of suicide death: AORs of 2.59 (95% CI, 1.33-5.04; p = 0.005) within 2 years and 2.13 (95% CI, 1.15-3.95; p = 0.017) within 3 years. However, there was no statistical significance in the increased risk of suicide death for pelvic fractures that had occurred ≥ 4 years ago (p > 0.05). Conclusions: Pelvic fractures in the elderly population increased the risk of suicide death within 3 years, suggesting the need for psychiatric support among elderly patients with pelvic fractures.

Comparative Interrupted Time Series Analysis of Long-term Direct Medical Costs in Patients With Hip Fractures and a Matched Cohort: A Large-database Study.

BACKGROUND: Previous studies on medical costs in patients with hip fractures have focused on medical costs incurred for a short period after the injury. However, patients often had comorbidities before their hip fractures that would have affected medical costs even had they not sustained a fracture. Consequently, these studies may have overestimated the costs associated with hip fractures and did not characterize the duration of increased medical costs adequately. Without knowing this crucial information, it is difficult to craft thoughtful health policy to support these patients' needs. QUESTIONS/PURPOSES: (1) To compare the direct medical costs for 5 years before fracture and up to 5 years after injury in a group of patients who underwent hip fracture surgery with a matched group of patients who did not experience a hip fracture, (2) to analyze the duration over which the increased direct medical costs associated with a hip fracture continues, and (3) to analyze whether there is a difference in direct medical costs according to age group using a nationwide claims database in South Korea. METHODS: The National Health Insurance Service Sample cohort in South Korea consisted of 1 million patients who were selected using a systematic, stratified, random sampling method from 48,222,537 individuals on December 31, 2006. Under a compulsory social insurance system established by the National Health Insurance Act, all patients were followed until 2015. Patients with hip fractures and matched controls were selected from the National Health Insurance Service sample of South Korea. Patients with hip fractures were defined as those who were hospitalized with a diagnosis of femoral neck fracture or intertrochanteric fracture and who underwent surgical treatment. We excluded patients with hip fractures before January 1, 2007 to ensure a minimum 5-year period that was free of hip fractures. Patients with hip fractures were matched with patients of the same age and gender at the date of admission to an acute care hospital for surgery (time zero). If patients with hip fractures died during the follow-up period, we performed matching among patients whose difference from the time of death was within 1 month. This method of risk-set matching was repeated sequentially for the next patient until the last patient with a hip fracture was matched. We then sequentially performed 1:5 random sampling for each risk set. A total of 3583 patients in the hip fracture cohort (patients with hip fractures) and 17,915 patients in the matched cohort (those without hip fractures) were included in this study. The mean age was 76 ± 9 years, and 70% were women in both groups. Based on the Charlson comorbidity index score, medication, and medical history, the patients with hip fractures had more comorbidities. Person-level direct medical costs per quarter were calculated for 5 years before time zero and up to 5 years after time zero. Direct medical costs were defined as the sum of that insurer's payments (that is, the National Health Insurance Service's payments), and that patient's copayments, excluding uncovered payments. We compared direct medical costs between patients with hip fractures and the patients in the matched cohort using a comparative interrupted time series analysis. The difference-in-difference estimate is the ratio of the differences in direct medical costs before and after time zero in the hip fracture cohort to the difference in direct medical costs before and after time zero in the matched cohort; the difference in difference estimates were calculated each year after injury. To identify changes in direct medical cost trends in patients with hip fractures and all subgroups, joinpoint regression was estimated using statistical software. RESULTS: The direct medical costs for the patients with hip fractures were higher than those for patients in the matched cohort at every year during the observation period. The difference in direct medical costs between the groups before time zero has increased every year. The direct medical costs in patients with hip fractures was the highest in the first quarter after time zero. Considering the differential changes in direct medical costs before and after time zero, hip fractures incurred additional direct medical costs of USD 2514 (95% CI 2423 to 2606; p < 0.01) per patient and USD 264 (95% CI 166 to 361; p < 0.01) per patient in the first and second years, respectively. The increase in direct medical costs attributable to hip fracture was observed for 1.5 to 2 years (difference-in-difference estimate at 1 year 3.0 [95% CI 2.8 to 3.2]; p < 0.01) (difference-in-difference estimate at 2 years 1.2 [95% CI 1.1 to 1.3]; p < 0.01; joinpoint 1.5 year). In the subgroups of patients younger than 65, patients between 65 and 85, and patients older than 85 years of age, the increase in direct medical costs attributable to hip fracture continued up to 1 year (difference-in-difference estimate ratio at 1 year 2.7 [95% CI 2.1 to 3.4]; p < 0.01; joinpoint 1 year), 1.5 to 2 years (difference-in-difference estimate ratio at 1 year 2.8 [95% CI 2.6 to 3.1]; p < 0.01; difference-in-difference estimate ratio at 2 years 1.2 [95% CI 1.1 to 1.3]; p < 0.01; joinpoint 1.5 years), and 39 months to 5 years (difference-in-difference estimate ratio at 1 year 5.2 [95% CI 4.4 to 6.2]; p < 0.01; difference-in-difference estimate ratio at 5 years 2.1 [95% CI 1.4 to 3.1]; p < 0.01; joinpoint 39 months) from time zero, respectively. CONCLUSION: The direct medical costs in patients with hip fractures were higher than those in the matched cohort every year during the 5 years before and after hip fracture. The increase in direct medical costs because of hip fractures was maintained for 1.5 to 2 years and was greater in older patients. Based on this, we suggest that health policies should focus on patients' financial and social needs, with particular emphasis on the first 2 years after hip fracture with stratification based on patients' ages. LEVEL OF EVIDENCE: Level II, economic analysis.