Online estimation of the case fatality rate using a run-off triangle data approach: An application to the Korean MERS outbreak in 2015.

This work is motivated by the recent Korean Middle East respiratory syndrome outbreak. We propose an easy online estimation procedure for the case fatality rate, ie, the proportion of deaths among the total cases during the course of an epidemic disease, which is an important indicator of the severity of a disease. The key step in our procedure is representing the data with the run-off triangle, which simultaneously takes into account two time axes, namely, the calendar and disease-duration times. We restructure the original data into run-off triangle data, where the cells contain the numbers of cured patients, deceased patients, and patients still having the disease at a given combination of calendar and disease-duration times. Based on the restructured run-off triangle data, we propose an online estimator of the case fatality rate. We numerically show the advantages of the proposed estimator compared to the existing estimators in the literature. Finally, we apply our procedure to the 2015 Korean Middle East respiratory syndrome outbreak data.

Phenotype difference between familial and sporadic ankylosing spondylitis in Korean patients.

Clustered occurrences of ankylosing spondylitis (AS) in family have been noticed. We evaluated patients with AS confirmed by the modified New York criteria for familial history of AS (one or more first to third degree relatives). The clinical characteristics and the recurrence risks (number of AS patients/number of familial members) of the familial AS compared to sporadic AS were investigated. Out of a total of 204 AS patients, 38 patients (18.6%) reported that they had a familial history of AS. The recurrence risks in the familial AS patients for first, second and third degree family members were 14.5%, 5.2%, and 4.4% respectively. Erythrocyte sedimentation rate (ESR) (22.6 ± 22.2 vs 35.4 ± 34.4, P=0.029) and C-reactive protein (CRP) (1.24 ± 1.7 vs 2.43 ± 3.3, P=0.003) at diagnosis, body mass index (21.9 ± 2.7 vs 23.7 ± 3.3, P=0.002) and frequency of oligoarthritis (13.2% vs 33.7%, P=0.021) were significantly lower in the familial form. The presence of HLA-B27 (97.4% vs 83.1%, P=0.044) was significantly higher in familial AS. In conclusion, Korean familial AS patients show a lower frequency of oligoarthritis, lower BMI, lower ESR and CRP at diagnosis and higher presence of HLA-B27.

Method to classify dental arch forms.

INTRODUCTION: The aim of this study was to propose a method to classify dental arch forms of subjects with normal occlusion into several types that can ensure both goodness of fit and clinical application. METHODS: We selected 306 subjects with normal occlusion from 15,836 young adults, recorded 14 reference points that defined the distance between 2 arch forms as the area between 2 arches, and then classified the dental arch forms by using the partitioning around medoids clustering and silhouette method. We measured tooth size, arch width, basal arch width, arch depth, mesiodistal angulations, and buccolingual inclinations. RESULTS: We identified 3 types of arch forms, and cross-classification of the maxillary by mandibular arch forms showed a more frequent distribution in the diagonal elements than in the off-diagonal elements. The 3 arch forms showed differences in tooth size, arch width, basal arch width, and inclination of the posterior teeth. CONCLUSIONS: By defining area discrepancies as distance measures and applying them to the cluster method by using medoids, the dental arch form can be classified keeping control for the extremes without bias. It is hoped that this method will have possible clinical applications in determining the shape and number of preformed orthodontic arch forms.

Variation of the intermaxillary tooth-size relationship in normal occlusion.

The purpose of this study was to explore the intermaxillary tooth-size relationship that is attributed to normal occlusion using multivariate cluster analysis, while simultaneously incorporating the full dentition as a data set. From the central incisor to the second molar, the tooth sizes of 307 subjects (188 males and 119 females; mean age ± standard deviation, 19.9 ± 3.3 years) with normal occlusion were investigated. Tooth-size data were analysed separately for the maxilla and the mandible. When clustering, the partitioning around medoids (PAM) algorithm was performed with the transformed data based on principal component analysis (PCA). After the subjects were classified into four groups, the cluster memberships were cross-classified, and the distribution pattern and intermaxillary tooth-size relationships were explored. Bolton tooth ratio showed a relatively wide range, and this was indicative of the variability in tooth size in subjects with a normal occlusion. However, the patterns of the intermaxillary tooth-size relationship were similar for males and females, and this result was concordant with the findings of the classic Bolton analysis. Using the multivariate approach to analyse the tooth-size data set of an individual patient and then comparing the results with the normal occlusion cluster has possible clinical applications in determining the amount and location of tooth-size control in orthodontics.

Nutritional Intervention for a Korean Adolescent with Atopic Dermatitis: a Case Report.

Atopic dermatitis (AD) is a common inflammatory skin disease in children worldwide but can affect individuals of all ages. Patients and parents of pediatric patients tend to restrict too much food because they think this aggravates or causes AD. However, there is a risk of nutrient deficiency owing to a lack of balanced diet. Herein, nutritional counseling was conducted to improve the eating habits of a patient with AD, promote nutritionally balanced meals, and consequently observe changes in the severity of AD. This report discusses the case of a 15-year-old male patient with AD who did not receive nutritional counseling previously but regularly ate breakfast and consumed fruits, beans, vegetables, and milk more frequently after counseling. His vegetable consumption increased from less than one plate a day before counseling to more than eight plates a day after counseling. This change was reflected in the nutritional quotient for adolescents (NQ-A) score. After consultation, eating habits improved, as indicated by a 1.2-, 2.4-, and 1.5-fold increase in NQ-A, diversity category, and balance category scores, respectively. The intake of protein, dietary fiber, vitamin A, vitamin D, vitamin K, vitamin C, niacin, calcium, potassium, magnesium, and water was inadequate before consultation and improved after consultation. The eating habits and severity of AD also improved after nutritional counseling. However, this result was not tested in a tightly controlled environment. It was difficult to conclude that only the eating habits affected the severity. Therefore, further research is needed.

Assessment of chemical equivalence in herbal materials using chromatographic fingerprints by combination of three similarity indices and three-dimensional kernel density estimation.

An intuitive and practical way to control chemical equivalence of secondary metabolites in herbal materials based on chromatographic fingerprints deserves a thorough discussion, yet it is relatively unexplored. For the first time, we propose a mixture of three similarity indices, the congruence coefficient, the average of the peak area ratios, and the larger value between the maximum peak area ratio and the reciprocal of the minimum peak area ratio, to make up for the weak points of some widely used similarity indices and to evaluate the chemical equivalence of two fingerprints from various perspectives. The three similarity values are fed into a three-dimensional kernel density estimation to determine the quality of herbal materials. This estimation enables precise detection of anomalies in the absence of prior quality determination experience. Forty Atractylodes samples similar in appearance and indiscriminately used for medical purposes were used to demonstrate the effectiveness of the developed approach. After a reference sample was postulated, a quality assessment of the 40 samples was performed using the three similarity values and the estimated kernel density. The samples that were judged by the developed approach to be of good quality were compared with those chosen by the most popular approach using decision criterion of a single similarity index. The benefits of the proposed approach were evident in that the qualified samples had the composition ratio and individual concentrations of multi-components closer to those of the reference in general, and their inter-sample deviation was significantly smaller.

Cluster analysis of tooth size in subjects with normal occlusion.

INTRODUCTION: Tooth-size studies are important in orthodontics. Our aim in this study was to establish normative data on tooth size with a clustering method. METHODS: Dental casts of 307 subjects with normal occlusion were examined. In these subjects, the tooth-size data sets in the maxilla and the mandible were clustered for men and women by using multivariate normal mixture models. This analysis clustered the data sets into groups of observations that were cohesive and separate from the other groups. The parameters were estimated with expectation-maximization procedures, and the number of clusters was selected via the Bayesian information criterion. RESULTS: Seven heterogeneous clusters in men and 4 clusters in women were identified. This study indicated that, in normal occlusion, tooth sizes are variable. These heterogeneities in the normal occlusion group seem to have contributed to the variability found in normative data. CONCLUSIONS: The method used in this study seems to provide a more substantive design for artificial teeth and add an additional dimension in the process of diagnosis of patients. Further applications seem possible in dental anthropometry by simultaneously dealing with the full dentition as a data set.

Respiratory symptoms and undiagnosed airflow obstruction in middle-aged adults: the Korean Health and Genome Study.

BACKGROUND: The prevalence of undiagnosed airflow obstruction is difficult to measure since it requires screening in population-based samples to identify individuals free of clinical symptoms. The purpose of this report is to examine the prevalence of undiagnosed airflow obstruction and its relation with respiratory symptoms in middle-age adults in the Korean Health and Genome (KHG) Study. METHODS: The KHG study is an ongoing population-based study of Korean adults aged 40 to 69 years. The current report includes 8,140 men and women without a pulmonary disorder or obstructive lung disease. In this sample, undiagnosed airflow obstruction was defined on the basis of spirometric testing and in the absence of a medical history or a recognized pulmonary disorder. Respiratory symptoms included chronic cough, chronic phlegm, wheezing, and shortness of breath. RESULTS: Undiagnosed airflow obstruction was observed in 12.4% of the men (470 of 3,806 subjects) and in 3.5% of the women (152 of 4,334 subjects). In men, the age-adjusted prevalence of undiagnosed airflow obstruction increased consistently with increasing number of respiratory symptoms. In those who smoked, there was a 2.3-fold excess in its prevalence when three or more symptoms were present, as compared to when they were absent (27.4% vs 12.0%, p < 0.001). A 2.4-fold excess (20.6% vs 8.5%, p = 0.004) was observed in nonsmoking men, in whom respiratory symptoms were consistently less common than in those who smoked. Respiratory symptoms were unrelated to undiagnosed airflow obstruction in women smokers, although only 3.9% smoked cigarettes. In women who were nonsmokers, the prevalence of undiagnosed airflow obstruction increased from 2.3% in those without a respiratory symptom to 6.0% when three or more symptoms were present (p = 0.003). CONCLUSIONS: Findings suggest that undiagnosed airflow obstruction is common in Korea with several respiratory symptoms. Whether respiratory symptoms with associations with undiagnosed airflow obstruction can be used to design early intervention strategies that prevent or delay the onset of COPD and its disabling consequences warrants further study.

Relationships between respiratory symptoms and FEV1 in men and women with normal lung function: The Korean Health and Genome Study.

Although the prevalence of chronic obstructive pulmonary disease (COPD) and its relationship with respiratory symptoms are well documented, few studies have focused on individuals with normal lung function, particularly in developed regions of Asia. The purpose of this report is to examine the relationship between respiratory symptoms and FEV1 in a population-based sample of Korean men and women with normal lung function. Subjects comprised 7518 individuals aged 40-69 years without airflow obstruction based on spirometric testing and in the absence of a medical history of pulmonary disease. Respiratory symptoms included chronic cough, chronic phlegm, wheezing, and shortness of breath. In men, the age-adjusted mean FEV1 was lower by 165 ml in smokers and 133 ml in nonsmokers in the presence versus the absence of wheezing (p < 0.05). While walking at a usual pace, FEV1 in smoking men was 210 ml lower in the presence versus the absence of shortness of breath (p < 0.05). Among nonsmoking men, overall shortness of breath and shortness of breath while walking uphill were associated with a lower FEV1 by 56 and 80 ml, respectively) versus those who reported having no shortness of breath (p < 0.05). Respiratory symptoms were unrelated to FEV1 in women smokers, although only 3.5% smoked cigarettes. In nonsmoking women, FEV1 was lower by an average of 89 ml in the presence versus the absence of wheezing (p < 0.001). Nonsmoking women also had a lower FEV1 in the presence of shortness of breath (overall, while at rest, and while walking uphill or at a usual pace, p < 0.001). Our findings suggest that respiratory symptoms are associated with a lower FEV1 in men and nonsmoking women with normal lung function. Whether respiratory symptoms can be used to identify individuals at risk for developing COPD needs further study.