All-Cause and Cause-Specific Mortality Attributable to Seasonal Influenza: A Nationwide Matched Cohort Study

Background@#Although influenza poses substantial mortality burden, most studies have estimated excess mortality using time-aggregated data. Here, we estimated mortality risk and population attributable fraction (PAF) attributed to seasonal influenza using individual-level data from a nationwide matched cohort. @*Methods@#Individuals with influenza during four consecutive influenza seasons (2013–2017) (n = 5,497,812) and 1:4 age- and sex-matched individuals without influenza (n = 20,990,683) were identified from a national health insurance database. The endpoint was mortality within 30 days after influenza diagnosis. All-cause and cause-specific mortality risk ratios (RRs) attributed to influenza were estimated. Excess mortality, mortality RR, and PAF of mortality were determined, including for underlying disease subgroups. @*Results@#Excess mortality rate, mortality RR, and PAF of all-cause mortality were 49.5 per 100,000, 4.03 (95% confidence interval [CI], 3.63–4.48), and 5.6% (95% CI, 4.5–6.7%). Cause-specific mortality RR (12.85; 95% CI, 9.40–17.55) and PAF (20.7%; 95% CI, 13.2– 27.0%) were highest for respiratory diseases. In subgroup analysis according to underlying disorders, PAF of all-cause mortality was 5.9% (95% CI, 0.6–10.7%) for liver disease, 5.8% (95% CI, 2.9–8.5%) for respiratory disease, and 3.8% (95% CI, 1.4–6.1%) for cancer. @*Conclusion@#Individuals with influenza had a 4-fold higher mortality risk than individuals without influenza. Preventing seasonal influenza may lead to 5.6% and 20.7% reductions in all-cause and respiratory mortality, respectively. Individuals with respiratory disease, liver disease, and cancer may benefit from prioritization when establishing influenza prevention strategies.

Cost-Effectiveness of Rivaroxaban Compared to Warfarin for Stroke Prevention in Atrial Fibrillation

BACKGROUND AND OBJECTIVES@#Rivaroxaban is noninferior to warfarin for preventing stroke or systemic embolism in patients with high-risk atrial fibrillation (AF) and is associated with a lower rate of intracranial hemorrhage (ICH). We assessed the cost-effectiveness of rivaroxaban compared to adjusted-dose warfarin for the prevention of stroke in patients with nonvalvular AF.@*METHODS@#We built a Markov model using the Korean Health Insurance Review & Assessment Service database. The base-case analysis assumed a cohort of patients with prevalent AF who were aged 18 years or older without contraindications to anticoagulation.@*RESULTS@#Number of patients with CHA2DS2-VASc scores 0, 1 and ≥2 were 56 (0.2%), 1,944 (6.3%) and 28,650 (93.5%), respectively. In patients with CHA2DS2-VASc scores ≥2, the incidence rate of ischemic stroke was 3.11% and 3.76% in warfarin and rivaroxaban groups, respectively. The incidence rates of ICH were 0.42% and 0.15%, and those of gastrointestinal bleeding were 0.32% and 0.15% in warfarin and rivaroxaban, respectively. Patients with AF treated with rivaroxaban lived an average of 11.8 quality-adjusted life years (QALYs) at a lifetime treatment cost of $20,886. Those receiving warfarin lived an average of 11.4 QALYs and incurred costs of $17,151. Patients with rivaroxaban gained an additional 0.4 QALYs over a lifetime with an additional cost of $3,735, resulting in an incremental cost-effectiveness ratio of $9,707 per QALY.@*CONCLUSIONS@#Patients who had been treated with rivaroxaban may be a cost-effective alternative to warfarin for stroke prevention in Korean patients with AF.

Cost-Effectiveness of Rivaroxaban Compared to Warfarin for Stroke Prevention in Atrial Fibrillation

BACKGROUND AND OBJECTIVES: Rivaroxaban is noninferior to warfarin for preventing stroke or systemic embolism in patients with high-risk atrial fibrillation (AF) and is associated with a lower rate of intracranial hemorrhage (ICH). We assessed the cost-effectiveness of rivaroxaban compared to adjusted-dose warfarin for the prevention of stroke in patients with nonvalvular AF. METHODS: We built a Markov model using the Korean Health Insurance Review & Assessment Service database. The base-case analysis assumed a cohort of patients with prevalent AF who were aged 18 years or older without contraindications to anticoagulation. RESULTS: Number of patients with CHA2DS2-VASc scores 0, 1 and ≥2 were 56 (0.2%), 1,944 (6.3%) and 28,650 (93.5%), respectively. In patients with CHA2DS2-VASc scores ≥2, the incidence rate of ischemic stroke was 3.11% and 3.76% in warfarin and rivaroxaban groups, respectively. The incidence rates of ICH were 0.42% and 0.15%, and those of gastrointestinal bleeding were 0.32% and 0.15% in warfarin and rivaroxaban, respectively. Patients with AF treated with rivaroxaban lived an average of 11.8 quality-adjusted life years (QALYs) at a lifetime treatment cost of $20,886. Those receiving warfarin lived an average of 11.4 QALYs and incurred costs of $17,151. Patients with rivaroxaban gained an additional 0.4 QALYs over a lifetime with an additional cost of $3,735, resulting in an incremental cost-effectiveness ratio of $9,707 per QALY. CONCLUSIONS: Patients who had been treated with rivaroxaban may be a cost-effective alternative to warfarin for stroke prevention in Korean patients with AF.

Effect of Socioeconomic Status and Underlying Disease on the Association between Ambient Temperature and Ischemic Stroke

PURPOSE: Inconsistent findings have been reported regarding the effect of ambient temperature on ischemic stroke. Furthermore, little is known about how underlying disease and low socioeconomic status influence the association. We, therefore, investigated the relationship between ambient temperature and emergency department (ED) visits for ischemic stroke, and aimed to identify susceptible populations. MATERIALS AND METHODS: Using medical claims data, we identified ED visits for ischemic stroke during 2005–2009 in Seoul, Korea. We conducted piecewise linear regression analyses to find optimum ambient temperature thresholds in summer and winter, and estimated the relative risks (RR) and 95% confidence intervals (CI) per a 1℃ increase in temperature above/below the thresholds, adjusting for relative humidity, holidays, day of the week, and air pollutant levels. RESULTS: There were 63564 ED visits for ischemic stroke. In summer, the risk of ED visits for ischemic stroke was not significant, with the threshold at 26.8℃. However, the RRs were 1.055 (95% CI, 1.006–1.106) above 25.0℃ in medical aid beneficiaries and 1.044 (1.007–1.082) above 25.8℃ in patients with diabetes. In winter, the risk of ED visits for ischemic stroke significantly increased as the temperature decreased above the threshold at 7.2℃. This inverse association was significant also in patients with hypertension and diabetes mellitus above threshold temperatures. CONCLUSION: Ambient temperature increases above a threshold were positively associated with ED visits for ischemic stroke in patients with diabetes and medical aid beneficiaries in summer. In winter, temperature, to a point, and ischemic stroke visits were inversely associated.

Short-term Effects of Ambient Air Pollution on Emergency Department Visits for Asthma: An Assessment of Effect Modification by Prior Allergic Disease History / 예방의학회지

OBJECTIVES: The goal of this study was to investigate the short-term effect of ambient air pollution on emergency department (ED) visits in Seoul for asthma according to patients’ prior history of allergic diseases. METHODS: Data on ED visits from 2005 to 2009 were obtained from the Health Insurance Review and Assessment Service. To evaluate the risk of ED visits for asthma related to ambient air pollutants (carbon monoxide [CO], nitrogen dioxide [NO₂], ozone [O₃], sulfur dioxide [SO₂], and particulate matter with an aerodynamic diameter <10 μm [PM₁₀]), a generalized additive model with a Poisson distribution was used; a single-lag model and a cumulative-effect model (average concentration over the previous 1-7 days) were also explored. The percent increase and 95% confidence interval (CI) were calculated for each interquartile range (IQR) increment in the concentration of each air pollutant. Subgroup analyses were done by age, gender, the presence of allergic disease, and season. RESULTS: A total of 33 751 asthma attack cases were observed during the study period. The strongest association was a 9.6% increase (95% CI, 6.9% to 12.3%) in the risk of ED visits for asthma per IQR increase in O₃ concentration. IQR changes in NO₂ and PM₁₀ concentrations were also significantly associated with ED visits in the cumulative lag 7 model. Among patients with a prior history of allergic rhinitis or atopic dermatitis, the risk of ED visits for asthma per IQR increase in PM₁₀ concentration was higher (3.9%; 95% CI, 1.2% to 6.7%) than in patients with no such history. CONCLUSIONS: Ambient air pollutants were positively associated with ED visits for asthma, especially among subjects with a prior history of allergic rhinitis or atopic dermatitis.

Admission route and use of invasive procedures during hospitalization for acute myocardial infarction: analysis of 2007-2011 National Health Insurance database / 한국역학회지

OBJECTIVES: The goal of this study was to investigate trends in admission to the emergency department and the use of invasive or surgical procedures during hospitalization for acute myocardial infarction (AMI) in Korea. METHODS: The National Health Insurance (NHI) claims database between 2007 and 2011 was used. We identified all admission claims that included codes from the tenth revision of the International Classification of Diseases beginning with I21 as the primary or secondary diagnosis. Information about the admission route, admission date, discharge date, and whether coronary artery angiography, angioplasty, or bypass surgery was performed was also obtained from the NHI database. RESULTS: Of the 513,886 relevant admission claims over the five years encompassed by this study, 295,001 discrete episodes of admission for AMI were identified by analyzing the date and length of each admission and the interval between admissions. The number of AMI admissions gradually decreased from 66,883 in 2007 to 47,656 in 2011. The number and proportion of admissions through the emergency department also decreased from 38,118 (57.0%) in 2007 to 24,001 (50.4%) in 2011. However, during the same period, admissions in which invasive or surgical procedures were performed increased from 15,342 (22.9%) to 17,505 (36.7%). CONCLUSIONS: The reported numbers of emergency department visits and admissions for AMI decreased from 2007 to 2011. However, only a small portion of the patients underwent invasive or surgical procedures during hospitalization, although the number of admissions involving invasive or surgical procedures has increased. These findings suggest that simply counting the number of admission claims cannot provide valid information on trends in AMI occurrence.

Changes in the Practice of Coronary Revascularization between 2006 and 2010 in the Republic of Korea

PURPOSE: Evidence suggests that technological innovations and reimbursement schemes of the National Health Insurance Service may have impacted the management of coronary artery disease. Thus, we investigated changes in the practice patterns of coronary revascularization. MATERIALS AND METHODS: Revascularization and in-hospital mortality among Koreans > or =20 years old were identified from medical claims filed between 2006 and 2010. The age- and sex-standardized procedure rate per 100000 person-years was calculated directly from the distribution of the 2008 Korean population. RESULTS: The coronary revascularization rate increased from 116.1 (95% confidence interval, 114.9-117.2) in 2006 to 131.0 (129.9-132.1) in 2010. Compared to the rate ratios in 2006, the rate ratios for percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) surgery in 2010 were 1.16 (1.15-1.17) and 0.80 (0.76-0.84), respectively. Among patients who received PCI, the percentage with drug-eluting stents increased from 89.1% in 2006 to 93.0% in 2010. In-hospital mortality rates from PCI significantly increased during the study period (p=0.03), whereas those from CABG significantly decreased (p=0.01). The in-hospital mortality rates for PCI and CABG were higher in elderly and female patients and at the lowest-volume hospitals. CONCLUSION: The annual volume of coronary revascularization continuously increased between 2006 and 2010 in Korea, although this trend differed according to procedure type. A high percentage of drug-eluting stent procedures and a high rate of in-hospital mortality at low-volume hospitals were noted.

Effect of an abdominal obesity management program on dietary intake, stress index, and waist to hip ratio in abdominally obese women: Focus on comparison of the WHR decrease and WHR increase groups

This study was conducted to evaluate the effects of an abdominal obesity management program on dietary intake, stress index, and waist to hip ratio (WHR) in abdominally obese women. The subjects were 195 adult abdominally obese women (WHR > or = 0.80) who had been participating in a nutrition education (total of nine times) and dietary habits and life style modification programs (total of six times) for 12 weeks. The abdominal obesity management program focused on the nutrition provided by breakfast, lunch, and dinner, proper dietary habits, and practices to improve life style. The subjects were divided into a WHR decrease group and a WHR increase group according to changes in the WHR. Daily nutrient intake was assessed with a 3-day food record, body measurements and blood vessel age, stress index, and a health index that were measured at baseline and after 12 weeks. After the intervention, weight, waist circumference, hip circumference, WHR, and body mass index (BMI) decreased significantly in the WHR decrease group. Energy intake increased from 1486.2 kcal to 1541.4 kcal with a significant improvement in nutrient density for animal protein, total fat, animal fat, fiber, calcium, phosphorus, zinc, vitamin B6, vitamin C, vitamin E, and saturated fatty acids in the WHR decrease group. Additionally, dietary diversity increased significantly in the WHR decrease group compared to that in the WHR increase group. The WHR decrease group showed a significant improvement in the stress and health indices. Changes in WHR were correlated with changes in nutrient intake (animal protein, total fat, animal fat, plant fat, fiber, calcium, iron, potassium, vitamin A, vitamin B2, vitamin B6, vitamin C, and folate) and medical index profiles (stress and indices) adjusted for age, birth status, baseline BMI, and baseline WHR. These results show that an abdominal obesity management program was effective not only for reducing the WHR but also to improve dietary intake and the stress index in abdominally obese women.