Statistical estimations for Plasmodium vivax malaria in South Korea

OBJECTIVE@#To calculate the numbers of weekly infections and prevalence of malaria, and to predict future trend of malaria incidences in South Korea.@*METHODS@#Weekly incidences of malaria for 13 years from the period 2001-2013 in South Korea were analyzed. The back-calculation equations were used with incubation period distributions. The maximum likelihood estimation for Poisson model was also used. The confidence intervals of the estimates were obtained by a bootstrap method. A regression model for time series of malaria incidences over 13 years was fitted by the non-linear least squares method, and used to predict futuretrend.@*RESULTS@#The estimated infection curve is narrower and more concentrated in the summer than in the incidence distribution. Infection started around the 19th week and was over around the 41st week. The maximum weekly infection 110 was obtained at the 29th week. The prevalence at the first week was around 496 persons, the minimum number was 366 at 22nd week, and the maximum prevalence was 648 at 34th week. Prevalence drops in late spring with people that falling ill and had had long incubation periods and rose in the summer with new infections. Our future forecast based on the regression model was that an increase at year 2014 compared to 2013 may reach a peak (at maximum about 70 weekly cases) at year 2015, with a decreasing trend after then.@*CONCLUSIONS@#This work shows that back-calculation methods could work well in estimating the infection rates and the prevalence of malaria. The obtained results can be useful in establishing an efficient preventive program for malaria infection. The method presented here can be used in other countries where incidence data and incubation period are available.

Statistical estimations for Plasmodium vivax malaria in South Korea

Objective: To calculate the numbers of weekly infections and prevalence of malaria, and to predict future trend of malaria incidences in South Korea. Methods: Weekly incidences of malaria for 13 years from the period 2001-2013 in South Korea were analyzed. The back-calculation equations were used with incubation period distributions. The maximum likelihood estimation for Poisson model was also used. The confidence intervals of the estimates were obtained by a bootstrap method. A regression model for time series of malaria incidences over 13 years was fitted by the non-linear least squares method, and used to predict futuretrend. Results: The estimated infection curve is narrower and more concentrated in the summer than in the incidence distribution. Infection started around the 19th week and was over around the 41st week. The maximum weekly infection 110 was obtained at the 29th week. The prevalence at the first week was around 496 persons, the minimum number was 366 at 22nd week, and the maximum prevalence was 648 at 34th week. Prevalence drops in late spring with people that falling ill and had had long incubation periods and rose in the summer with new infections. Our future forecast based on the regression model was that an increase at year 2014 compared to 2013 may reach a peak (at maximum about 70 weekly cases) at year 2015, with a decreasing trend after then. Conclusions: This work shows that back-calculation methods could work well in estimating the infection rates and the prevalence of malaria. The obtained results can be useful in establishing an efficient preventive program for malaria infection. The method presented here can be used in other countries where incidence data and incubation period are available.

Statistical estimations forPlasmodium vivaxmalaria in South Korea

Objective:To calculate the numbers of weekly infections and prevalence of malaria, and to predict future trend of malaria incidences in South Korea.Methods:Weekly incidences of malaria for 13 years from the period 2001-2013 in South Korea were analyzed. The back-calculation equations were used with incubation period distributions. The maximum likelihood estimation for Poisson model was also used. The confidence intervals of the estimates were obtained by a bootstrap method. A regression model for time series of malaria incidences over 13 years was fitted by the non-linear least squares method, and used to predict futuretrend. Results:The estimated infection curve is narrower and more concentrated in the summer than in the incidence distribution. Infection started around the 19th week and was over around the 41st week. The maximum weekly infection 110 was obtained at the 29th week. The prevalence at the first week was around 496 persons, the minimum number was 366 at 22nd week, and the maximum prevalence was 648 at 34th week. Prevalence drops in late spring with people that falling ill and had had long incubation periods and rose in the summer with new infections. Our future forecast based on the regression model was that an increase at year 2014 compared to 2013 may reach a peak (at maximum about 70 weekly cases) at year 2015, with a decreasing trend after then.Conclusions:This work shows that back-calculation methods could work well in estimating the infection rates and the prevalence of malaria. The obtained results can be useful in establishing an efficient preventive program for malaria infection. The method presented here can be used in other countries where incidence data and incubation period are available.

Treatment of Rheumatoid Arthritis Patients with Chronic Hepatitis B: Analysis of Korean National Health Insurance Claims Data

OBJECTIVE: There are currently limited treatment options for rheumatoid arthritis (RA) patients with chronic hepatitis B (CHB). In the process of pursuing further treatment strategies for this subgroup of patients, it is prudent to study what medications have been commonly prescribed, particularly for disease modifying anti-rheumatic agents (DMARDs) in Korea. METHODS: We analyzed the Korean National Health Insurance claims database (2007~2009) of RA patients through co-working with the Clinical Research Center for RA (CRCRA). Patients with CHB were defined by an algorithm including prescription information, blood tests, and the ICD-10 code. RESULTS: There were 8,677 CHB patients (3.8%) among 226,592 RA patients in the database. The age distribution or gender difference in CHB patients was comparable to the general RA population. Hydroxychloroquine was the most frequently (66.2%) prescribed DMARD. Thirty four percent of CHB patients had been prescribed with methotrexate (MTX) during the study period; most of them without concomitant anti-viral treatment. About 3% of RA patients with CHB were prescribed with TNF inhibitors. CONCLUSION: Apart from the published expert recommendations, MTX still seems to be one of the main DMARDs prescribed to Korean RA patients with CHB. This is most likely due to the lack of evidence-based, effective treatment strategies for this subgroup of patients.

Treatment of Rheumatoid Arthritis Patients with Chronic Hepatitis B: Analysis of Korean National Health Insurance Claims Data

OBJECTIVE: There are currently limited treatment options for rheumatoid arthritis (RA) patients with chronic hepatitis B (CHB). In the process of pursuing further treatment strategies for this subgroup of patients, it is prudent to study what medications have been commonly prescribed, particularly for disease modifying anti-rheumatic agents (DMARDs) in Korea. METHODS: We analyzed the Korean National Health Insurance claims database (2007~2009) of RA patients through co-working with the Clinical Research Center for RA (CRCRA). Patients with CHB were defined by an algorithm including prescription information, blood tests, and the ICD-10 code. RESULTS: There were 8,677 CHB patients (3.8%) among 226,592 RA patients in the database. The age distribution or gender difference in CHB patients was comparable to the general RA population. Hydroxychloroquine was the most frequently (66.2%) prescribed DMARD. Thirty four percent of CHB patients had been prescribed with methotrexate (MTX) during the study period; most of them without concomitant anti-viral treatment. About 3% of RA patients with CHB were prescribed with TNF inhibitors. CONCLUSION: Apart from the published expert recommendations, MTX still seems to be one of the main DMARDs prescribed to Korean RA patients with CHB. This is most likely due to the lack of evidence-based, effective treatment strategies for this subgroup of patients.

Differences in Obesity Rates Between People With and Without Disabilities and the Association of Disability and Obesity: A Nationwide Population Study in South Korea / 예방의학회지

OBJECTIVES: The objective of this study was to identify the differences in obesity rates among people with and without disabilities, and evaluate the relationship between obesity rates and the existence of disabilities or characteristics of disabilities. METHODS: Mass screening data from 2008 from the National Disability Registry and National Health Insurance (NHI) are used. For analysis, we classified physical disability into three subtypes: upper limb disability, lower limb disability, and spinal cord injury. For a control group, we extracted people without disabilities by each subtype. To adjust for the participation rate in the NHI mass screening, we calculated and adopted the weight stratified by sex, age, and grade of disability. Differences in obesity rates between people with and without disabilities were examined by a chi-squared test. In addition, the effect of the existence of disabilities and grade of disabilities on obesity was examined by multiple logistic regression analysis. RESULTS: People with disabilities were found to have a higher obesity rate than those without disabilities. The obesity rates were 35.2% and 35.0% (people with disabilities vs. without disabilities) in the upper limb disability, 44.5% and 34.8% in the lower limb disability, 43.4% and 34.6% in the spinal cord injury. The odds for existence of physical disability and grade of disability are higher than the non-disabilities. CONCLUSIONS: These results show that people with physical disability have a higher vulnerability to obesity.

Factors Affecting Public Prejudice and Social Distance on Mental Illness: Analysis of Contextual Effect by Multi-level Analysis / 예방의학회지

OBJECTIVES: While there have been many quantitative studies on the public's attitude towards mental illnesses, it is hard to find quantitative study which focused on the contextual effect on the public's attitude. The purpose of this study was to identify factors that affect the public's beliefs and attitudes including contextual effects. METHODS: We analyzed survey on the public's beliefs and attitudes towards mental illness in Korea with multi-level analysis. We analyzed the public's beliefs and attitudes in terms of prejudice as an intermediate outcome and social distance as a final outcome. Then, we focused on the associations of factors, which were individual and regional socio-economic factors, familiarity, and knowledge based on the comparison of the intermediate and final outcomes. RESULTS: Prejudice was not explained by regional variables but was only correlated with individual factors. Prejudice increased with age and decreased by high education level. However, social distance controlling for prejudice increased in females, in people with a high education level, and in regions with a high education level and a high proportion of the old. Therefore, social distance without controlling for prejudice increased in females, in the elderly, in highly educated people, and in regions with a high education and aged community. CONCLUSIONS: The result of the multi-level analysis for the regional variables suggests that social distance for mental illness are not only determined by individual factors but also influenced by the surroundings so that it could be tackled sufficiently with appropriate considering of the relevant regional context with individual characteristics.