American public health promoter: William Henry·Welch / 中华疾病控制杂志

William Henry·Welch (1850-1934) was a famous American pathologist, bacteriologist and medical school administrator. He introduced European exquisite experimental technology, frontier bacteriology theory and innovative scientific research thinking into American medical field, promoted American health reform, and promoted the development of public health in the United States. At the same time, Welch founded the Johns Hopkins School of Hygiene and Public Health, the first public health school in the United States, and provided a blueprint for world public health education.

Project Hawkeye: A cross-sectional study on the prevalence of undetected refractive errors in schoolage children / The Health Sciences Journal

Introduction@#In the Philippines, essential eye care services are not easily accessible especially for those in lower income groups, putting public elementary school students at risk for underdiagnosis of problems in visual acuity. The objective of this investigation was to determine prevalence of undetected refractive errors among public elementary students using the Welch Allyn Spot™ Vision Screener.@*Methods @#A cross-sectional design was used in this investigation to estimate the prevalence of uncorrected refractive errors in the first grade students in San Perfecto Elementary School using Welch Allyn Spot™ Vision Screener (Photoscreener). Eligible students who gave informed consent and assent answered a questionnaire and underwent an eye examination. The prevalence of undetected errors of refraction were computed for the sample population and for selected demographic variables.@*Results @#Approximately one out of four students (24.53%) had errors of refraction, with the most common type being astigmatism (22.64%), followed by myopia (3.77%) and hyperopia (2.83%).@*Conclusion @#This study revealed a high prevalence of undetected refractive errors among school-age children, higher than current published data (5%) in the Philippines.

Comparing discrete distributions when the sample space is smal / Comparando las distribuciones discretas cuando el espacio muestral es pequeño

This paper describes two new methods for comparing two independent, discrete distributions, when the sample space is small, using an extension of the Storer-Kim method for comparing independent binomials. These methods are relevant, for example, when comparing groups based on a Likert scale, which was the motivation for the paper. In essence, the goal is to test the hypothesis that the cell probabilities associated with two independent multinomial distributions are equal. Both a global test and a multiple comparison procedure are proposed. The small-sample properties of both methods are compared to four other techniques via simulations: Cliff's generalization of the Wilcoxon-Mann-Whitney test that effectively deals with heteroscedasticity and tied values, Yuen's test based on trimmed means, Welch's test and Student's t test. For the simulations, data were generated from beta-binomial distributions. Both symmetric and skewed distributions were used. The sample space consisted of the integers 0(1)4 or 0(1)10. For the global test that is proposed, when testing at the 0.05 level, simulation estimates of the actual Type I error probability ranged between 0.043 and 0.059. For the new multiple comparison procedure, the estimated family wise error rate ranged between 0.031 and 0.054 for the sample space 0(1)4. But for 0(1)10, the estimates dropped as low as 0.016 in some situations. Given the goal of comparing means, Student's t is well known to have practical problems when distributions differ. Similar problems are found here among the situations considered. No single method dominates in terms of power, as would be expected, because different methods are sensitive to different features of the distributions being compared. But in general, one of the new methods tends to have relatively good power based on both simulations and experience with data from actual studies. If, however, there is explicit interest in comparing means, rather than comparing the cell probabilities, Welch's test was found to perform well. The new methods are illustrated using data from the Well-Elderly Study where the goal is to compare groups in terms of depression and the strategies used for dealing with stress.

En este artículo se describen dos nuevos métodos para comparar dos distribuciones discretas independientes, cuando el espacio muestral es pequeño, usando una extensión del método Storer-Kim para comparar binomios independientes. Estos métodos son relevantes, por ejemplo, cuando se comparan grupos basados en una escala Likert, la cual motivó la escritura del artículo. En esencia, el objetivo es evaluar la hipótesis de que las probabilidades de células asociadas con dos distribuciones multinominales independientes son iguales. Se propone una prueba global y un procedimiento de comparación múltiple. Las propiedades de las muestras pequeñas de ambos métodos fueron comparadas con otras cuatro técnicas a través de simulaciones: generalización de Cliff de la prueba de Wilcoxon-Mann-Whitney que trata eficazmente con heteroscedasticidad y valores vinculados, la prueba de Yuen basada en medias truncadas, la prueba de Welch y la prueba t de Student. Para las simulaciones, los datos se generaron a partir de distribuciones beta-binomiales. Se utilizaron distribuciones tanto simétricas como asimétricas. El espacio muestral consistió en los enteros 0(1)4 o 0(1)10. Para la prueba global que se propone, cuando se evaluó al nivel de 0.05, la simulación estimó la probabilidad del error tipo I osciló entre 0.043 y 0.059. Para el nuevo procedimiento de comparación múltiple, la tasa de error estimada oscilaba entre 0.031 y 0.054 para el espacio de la muestra 0(1)4. Pero para 0(1)10, las estimaciones fueron tan bajas como 0.016 en algunas situaciones. Teniendo en cuenta el objetivo de la comparación de medias, la prueba t de Student es bien conocida por tener problemas prácticos cuando distribuciones difieren. Problemas similares se encuentraron entre las situaciones consideradas. No existe un único método que domina en términos de poder, como sería de esperar, debido a que los diferentes métodos son sensibles a las diferentes características de las distribuciones que son comparadas. Pero en general, uno de los nuevos métodos tiende a tener relativamente buen poder basado tanto en simulaciones y la experiencia con los datos de estudios reales. Si, sin embargo, existe un interés explícito en comparar medias, en lugar de comparar las probabilidades de celda, la prueba de Welch se encuentra que tiene un buen desempeño. Los nuevos métodos se ilustran usando datos del estudio Well-Elderly donde el objetivo es comparar los grupos en cuanto a la depresión y las estrategias utilizadas para hacer frente al estrés.

Professionalizing Public Health as a Branch of Medicine: The Emergence of the Johns Hopkins School of Public Health in the United States in the 1910s / 의사학

After comparing the sanitary reform movement in England, France, and Germany, the paper discusses how bacteriological discovery in the 1880s was a turning point in dividing the interests of the 'old' public health advocates pursuing social reforms from the 'new' public health advocates pursuing scientific reforms. In the 1910s, the United States witnessed the dawning of a new era in public health and the rising concern for a national health program. The American pioneers of public health became to recognize the need for new kinds of public health professionals. In this period, the Rockefeller Foundation initiated the designing of a new model for a school of public health in the United States. Most leaders of public health arguably participated in drawing up the model for the school of public health. While William H Welch was inclined towards an 'Institute of Hygiene' similar to that of Max von Pettenkoffer in Munich, Wickeliffe Rose insisted that the 'School of Public Health' be established by all the state governments. The 'Welch-Rose Report,' with a basic framework consisting of Welch's ideas, provided a theoretical basis for the classic model of the school of public health. Abraham Flexner, who firmly believed in a biomedical model of public health, decidedly contributed to the Johns Hopkins, disregarding strong rivals such as Harvard and Columbia. The 'Johns Hopkins School of Hygiene and Public Health' was to become a medicalized version of public health. Finally, the paper raises an intriguing question: Should the schools of public health in Korea follow the Welch model or the Rose model? Is there another option?

Pull-through Welch procedure for the lower rectal carcinoma: a report of 28 cases / 中国普通外科杂志

Objective To find a novel operative modality with sphincter preservation in the treatment of middle and low rectal carcinoma. Methods Pull through lower resection was performed on 28 rectal cancer patients. The distance between the anal verge and the lower margin of the tumor was 6～8cm(20 patients) or 8～10cm(8 patients), including 8 patients in Dukes A stage, 16 Dukes B and 4 Dukes C. The resected line from tumor distal margin was 2cm, 3cm, and 4cm, respectively. Results There was no operative death, anastomotic fistula or anastomotic stenosis in these cases. Mean follow up period was 30 months. Local recurrence was found in two cases (7.1%) 18 months after the operation, and 26 cases were cancer free till the end of the follow up. Defecation was satisfactorily controlled 8～12 weeks after the operation. Conclusions Pull through Welch procedure could meet the criterion of the radical resection of rectal carcinoma,and keep the internal and external sphincter muscles intact in the superior lower anterior resection. The normal defecationcan can maintain after the operation due to the preservation of internal and external sphincter muscles.