PURPOSE: Antithrombotic therapy could be related with nuisance bleeding. This study investigated whether vitreous hemorrhage (VH) is associated with specific types of antithrombotic medication in patients with atrial fibrillation (AF). MATERIALS AND METHODS: In the Korean National Health Insurance Service National Sample Cohort, we identified 9352 antiplatelet/anticoagulant-treated AF patients. The occurrence of VH was compared between warfarin (n=1493) and a propensity score (PS)-matched antiplatelet group (n=1493) and between warfarin (n=1493) and a PS-matched warfarin+antiplatelet group (n=1493). RESULTS: The outcomes of VH were lower in the warfarin than in the matched antiplatelet (1.45 vs. 3.72 events/1000 patient-years) and matched warfarin+antiplatelet groups (1.45 vs. 6.87 events/1000 patient-years). Compared with warfarin, the risk of VH increased with antiplatelet [adjusted hazard ratio (aHR) 3.90; 95% confidence interval (CI) 1.22–12.4, p=0.022] and warfarin+antiplatelet agents (aHR 4.39, 95% CI 1.74–11.2, p=0.002). Compared with warfarin only, warfarin+antiplatelet agents increased the risk of VH in patients ≥65 years, regardless of gender and hypertension. The risk of VH was significantly higher with dual antiplatelet therapy (aHR: 5.02, 95% CI: 1.56–16.2, p=0.007) or in dual (aHR: 5.02, 95% CI: 1.74–14.5, p=0.003) or triple therapy using warfarin and antiplatelet agents than with warfarin monotherapy (aHR: 6.12, 95% CI: 1.76–21.3, p=0.004). CONCLUSION: Dual antiplatelet or triple therapy increased the risk of VH significantly, compared to warfarin monotherapy. Considering the low efficacy of preventing ischemic stroke and high risk of bleeding, dual or triple therapy using warfarin and antiplatelet agents should be avoided to prevent VH in AF patients.
Atrial Fibrillation* ; Cohort Studies* ; Hemorrhage ; Humans ; Hypertension ; National Health Programs* ; Platelet Aggregation Inhibitors ; Propensity Score ; Stroke ; Vitreous Hemorrhage* ; Warfarin

Background: Vaccine safety surveillance is important because it is related to vaccine hesitancy, which affects vaccination rate. To increase confidence in vaccination, the active monitoring of vaccine adverse events is important. For effective active surveillance, we developed and verified a machine learning-based active surveillance system using national claim data. Methods: We used two databases, one from the Korea Disease Control and Prevention Agency, which contains flu vaccination records for the elderly, and another from the National Health Insurance Service, which contains the claim data of vaccinated people. We developed a casecrossover design based machine learning model to predict the health outcome of interest events (anaphylaxis and agranulocytosis) using a random forest. Feature importance values were evaluated to determine candidate associations with each outcome. We investigated the relationship of the features to each event via a literature review, comparison with the Side Effect Resource, and using the Local Interpretable Model-agnostic Explanation method. Results: The trained model predicted each health outcome of interest with a high accuracy (approximately 70%). We found literature supporting our results, and most of the important drug-related features were listed in the Side Effect Resource database as inducing the health outcome of interest. For anaphylaxis, flu vaccination ranked high in our feature importance analysis and had a positive association in Local Interpretable Model-Agnostic Explanation analysis. Although the feature importance of vaccination was lower for agranulocytosis, it also had a positive relationship in the Local Interpretable Model-Agnostic Explanation analysis. Conclusion We developed a machine learning-based active surveillance system for detecting possible factors that can induce adverse events using health claim and vaccination databases. The results of the study demonstrated a potentially useful application of two linked national health record databases. Our model can contribute to the establishment of a system for conducting active surveillance on vaccination.

Background: Vaccine safety surveillance is important because it is related to vaccine hesitancy, which affects vaccination rate. To increase confidence in vaccination, the active monitoring of vaccine adverse events is important. For effective active surveillance, we developed and verified a machine learning-based active surveillance system using national claim data. Methods: We used two databases, one from the Korea Disease Control and Prevention Agency, which contains flu vaccination records for the elderly, and another from the National Health Insurance Service, which contains the claim data of vaccinated people. We developed a casecrossover design based machine learning model to predict the health outcome of interest events (anaphylaxis and agranulocytosis) using a random forest. Feature importance values were evaluated to determine candidate associations with each outcome. We investigated the relationship of the features to each event via a literature review, comparison with the Side Effect Resource, and using the Local Interpretable Model-agnostic Explanation method. Results: The trained model predicted each health outcome of interest with a high accuracy (approximately 70%). We found literature supporting our results, and most of the important drug-related features were listed in the Side Effect Resource database as inducing the health outcome of interest. For anaphylaxis, flu vaccination ranked high in our feature importance analysis and had a positive association in Local Interpretable Model-Agnostic Explanation analysis. Although the feature importance of vaccination was lower for agranulocytosis, it also had a positive relationship in the Local Interpretable Model-Agnostic Explanation analysis. Conclusion We developed a machine learning-based active surveillance system for detecting possible factors that can induce adverse events using health claim and vaccination databases. The results of the study demonstrated a potentially useful application of two linked national health record databases. Our model can contribute to the establishment of a system for conducting active surveillance on vaccination.

Purpose: Cardiovascular health (CVH) status is associated with several cardiovascular outcomes; however, correlations between changes in CVH status and risk of sudden cardiac death (SCD) are unknown. We aimed to evaluate associations between changes in CVH status and risk of SCD and all-cause death in older adults. Materials and Methods: We used data from the Korea National Health Insurance Service-Senior cohort database (2005–2012). Six metrics from the American Heart Association (smoking, body mass index, physical activity, blood pressure, total cholesterol, and fasting blood glucose) were used to calculate CVH scores. Changes in CVH status between two health checkups were categorized as low to low, low to high, high to low, and high to high. Results: We included 105200 patients whose CVH status for an initial and follow-up health checkup (2-year interval) was available. During a median of 5.2 years of follow-up after a second health checkup, 688 SCDs occurred. Compared to patients with a persistent low CVH status, those with a consistently high CVH status had a reduced risk of SCD [adjusted hazard ratio (HR), 0.69; 95% confidence interval (CI), 0.56–0.86] and all-cause death (adjusted HR, 0.74; 95% CI, 0.69–0.78). The risk of all-cause death followed similar trends. However, an inconsistent linear relationship was observed for changes in CVH status and the risk of SCD, but not of all-cause death. Conclusion Maintaining a high CVH status was associated with future risks of SCD and all-cause death among an older adult population.

BACKGROUND AND OBJECTIVES: Nationwide social inequalities of oral anticoagulation (OAC) usage after the introduction of non-vitamin K antagonist oral anticoagulants (NOACs) have not been well identified in patients with atrial fibrillation (AF). This study assessed overall rate and social inequalities of OAC usage after the introduction of NOAC in Korea.METHODS: Between January 2002 and December 2016, we identified 888,540 patients with AF in the Korea National Health Insurance system database. The change of OAC rate in different medical systems after the introduction of NOAC were evaluated.RESULTS: In all population, overall OAC use increased from 13.2% to 23.4% (p for trend <0.001), and NOAC use increased from 0% to 14.6% (p for trend <0.001). Compared with pre-reimbursement (0.48%), the annual increase of OAC use was significantly higher after partial (1.16%, p<0.001), and full reimbursement of OAC (3.72%, p<0.001). Full reimbursement of NOAC (adjusted odds ratio, 2.10; 95% confidence interval, 2.04–2.15) was independently associated with higher OAC use. However, the difference of overall OAC usage between tertiary referral hospitals and nursing or public health centers increased from 17.9% in 2010 to 36.8% in 2016. Moreover, usage rate of NOAC was significantly different among different medical systems from 37.2% at the tertiary referral hospital and 5.5% at nursing or public health centers.CONCLUSIONS: Introduction of NOACs in routine practice for stroke prevention in AF was associated with improved rates of overall OAC use. However, significant practice-level variations in OAC and NOAC use remain producing social inequalities of OAC despite full reimbursement.
Anticoagulants ; Atrial Fibrillation ; Humans ; Insurance ; Korea ; National Health Programs ; Nursing ; Odds Ratio ; Public Health ; Socioeconomic Factors ; Stroke ; Tertiary Care Centers

BACKGROUND AND OBJECTIVES: Nationwide social inequalities of oral anticoagulation (OAC) usage after the introduction of non-vitamin K antagonist oral anticoagulants (NOACs) have not been well identified in patients with atrial fibrillation (AF). This study assessed overall rate and social inequalities of OAC usage after the introduction of NOAC in Korea. METHODS: Between January 2002 and December 2016, we identified 888,540 patients with AF in the Korea National Health Insurance system database. The change of OAC rate in different medical systems after the introduction of NOAC were evaluated. RESULTS: In all population, overall OAC use increased from 13.2% to 23.4% (p for trend <0.001), and NOAC use increased from 0% to 14.6% (p for trend <0.001). Compared with pre-reimbursement (0.48%), the annual increase of OAC use was significantly higher after partial (1.16%, p<0.001), and full reimbursement of OAC (3.72%, p<0.001). Full reimbursement of NOAC (adjusted odds ratio, 2.10; 95% confidence interval, 2.04–2.15) was independently associated with higher OAC use. However, the difference of overall OAC usage between tertiary referral hospitals and nursing or public health centers increased from 17.9% in 2010 to 36.8% in 2016. Moreover, usage rate of NOAC was significantly different among different medical systems from 37.2% at the tertiary referral hospital and 5.5% at nursing or public health centers. CONCLUSIONS Introduction of NOACs in routine practice for stroke prevention in AF was associated with improved rates of overall OAC use. However, significant practice-level variations in OAC and NOAC use remain producing social inequalities of OAC despite full reimbursement.

Background: We aimed to investigate the comparative risk of fracture among patients with atrial fibrillation (AF) treated with warfarin or non-vitamin K antagonist oral anticoagulants (NOACs). Methods: Using the Korean National Health Insurance Service database, patients with AF who received a prescrip‑ tion for apixaban, dabigatran, rivaroxaban, or warfarin between 2013 and 2016 were included. Risk of major fractures (osteoporotic hip, vertebral, or pelvic fractures) were compared using inverse probability of treatment weighting. Results: There were 70,481 patients identified (41.3% women; mean [SD] age 70.5 [11.3] years); 16,992 apixaban, 22,514 dabigatran, 27,998 rivaroxaban, and 29,390 warfarin users. During a median follow-up of 390 days, 2412 major fractures occurred with weighted incidences per 100 patient-years of 2.56 for apixaban, 2.39 for dabigatran, 2.78 for rivaroxaban, and 3.43 for warfarin. NOAC use was associated with a lower risk for fracture than warfarin use: HR 0.70 (95% confidence interval [CI] 0.57–0.86) for apixaban, HR 0.69 (95% CI 0.60–0.78) for dabigatran, and HR 0.79 (95% CI 0.70–0.90) for rivaroxaban. In head-to-head comparisons between NOACs, there was no significant difference between apixaban and dabigatran. Rivaroxaban was associated with a higher risk for fracture than dabigatran (HR 1.15, 95% CI 1.02–1.31). Conclusion In patients with AF, NOAC use may result in a lower risk for osteoporotic fracture compared with warfa‑ rin use. Fracture risk does not seem to be altered by the choice of NOAC type, except for rivaroxaban. These associa‑ tions may help inform benefit–risk assessments when choosing between the different anticoagulant types.

Background: We aimed to investigate the comparative risk of fracture among patients with atrial fibrillation (AF) treated with warfarin or non-vitamin K antagonist oral anticoagulants (NOACs). Methods: Using the Korean National Health Insurance Service database, patients with AF who received a prescrip‑ tion for apixaban, dabigatran, rivaroxaban, or warfarin between 2013 and 2016 were included. Risk of major fractures (osteoporotic hip, vertebral, or pelvic fractures) were compared using inverse probability of treatment weighting. Results: There were 70,481 patients identified (41.3% women; mean [SD] age 70.5 [11.3] years); 16,992 apixaban, 22,514 dabigatran, 27,998 rivaroxaban, and 29,390 warfarin users. During a median follow-up of 390 days, 2412 major fractures occurred with weighted incidences per 100 patient-years of 2.56 for apixaban, 2.39 for dabigatran, 2.78 for rivaroxaban, and 3.43 for warfarin. NOAC use was associated with a lower risk for fracture than warfarin use: HR 0.70 (95% confidence interval [CI] 0.57–0.86) for apixaban, HR 0.69 (95% CI 0.60–0.78) for dabigatran, and HR 0.79 (95% CI 0.70–0.90) for rivaroxaban. In head-to-head comparisons between NOACs, there was no significant difference between apixaban and dabigatran. Rivaroxaban was associated with a higher risk for fracture than dabigatran (HR 1.15, 95% CI 1.02–1.31). Conclusion In patients with AF, NOAC use may result in a lower risk for osteoporotic fracture compared with warfa‑ rin use. Fracture risk does not seem to be altered by the choice of NOAC type, except for rivaroxaban. These associa‑ tions may help inform benefit–risk assessments when choosing between the different anticoagulant types.

Purpose: Heart failure (HF) and atrial fibrillation (AF) frequently coexist, with over 50% patients with HF having AF, while onethird of those with AF develop HF. Differences in obesity-mediated association between HF and HF-related AF among Asians and Europeans were evaluated. Materials and Methods: Using the Korean National Health Insurance Service-Health Screening (K-NHIS-HealS) cohort and the UK Biobank, we included 394801 Korean and 476883 UK adults, respectively aged 40–70 years. The incidence and risk of HF were evaluated based on body mass index (BMI). Results: The proportion of obese individuals was significantly higher in the UK Biobank cohort than in the K-NHIS-HealS cohort (24.2% vs. 2.7%, p<0.001). The incidence of HF and HF-related AF was higher among the obese in the UK than in Korea. The risk of HF was higher among the British than in Koreans, with adjusted hazard ratios of 1.82 [95% confidence interval (CI), 1.30–2.55] in KNHIS-HealS and 2.00 (95% CI, 1.69–2.37) in UK Biobank in obese participants (p for interaction <0.001). A 5-unit increase in BMI was associated with a 44% greater risk of HF-related AF in the UK Biobank cohort (p<0.001) but not in the K-NHIS-HealS cohort (p=0.277). Conclusion Obesity was associated with an increased risk of HF and HF-related AF in both Korean and UK populations. The higher incidence in the UK population was likely due to the higher proportion of obese individuals.