Diseño Óptimo de Estudios en Rehabilitación: Importancia del Tamaño Muestra / Optimal Design of Rehabilitation Studies: Importance of Sample Size

Este artículo aborda los principios esenciales para la estimación del tamaño muestral en estudios cuantitativos de ciencias de la rehabilitación y movimiento humano. Además, proporciona una guía práctica y accesible sobre el diseño de investigaciones rigurosas, abordando conceptos clave como la precisión, nivel de confianza, nivel de significancia y potencia estadística, fundamentales para obtener resultados válidos y confiables. También se explora cómo estos parámetros influyen en la generalización de hallazgos y la detección de diferencias significativas, así como la importancia de un tamaño muestral adecuado para que los futuros investigadores mejoren la calidad de sus estudios en campos de la rehabilitación y el movimiento humano.

This article addresses the essential principles for sample size estimation in quantitative studies of rehabilitation sciences and human movement. In addition, it provides a practical and accessible guide on the design of rigorous investigations, addressing key concepts such as precision, confidence level, significance level and statistical power, essential to obtain valid and reliable results. It also explores how these parameters influence the generalization of findings and the detection of significant differences, as well as the importance of an adequate sample size for future researchers to improve the quality of their studies in the fields of rehabilitation and human movement.

La muestra en ensayos clínicos aleatorizados con análisis interino / Samples in randomized clinical trials with interim analysis

RESUMEN En este artículo se introducen los ensayos clínicos aleatorizados y conceptos básicos de la inferencia estadística. Se presenta como calcular el tamaño de muestra por tipo de desenlace e hipótesis a probar, junto con el código en el lenguaje de programación R para realizar su aplicación. Se presentan cuatro métodos para realizar el ajuste del tamaño de muestra original, cuando se planean análisis interinos. De una manera sencilla y concreta se busca realizar una introducción a estos temas, considerando las expresiones matemáticas que soportan los resultados y su implementación en programas estadísticos disponibles. Con el fin de acercar a los estudiantes de áreas de la salud a la estadística y al uso de programas estadísticos, aspectos poco considerados en su formación.

ABSTRACT This article introduces randomized clinical trials and basic concepts of statistical inference. We present methods for calculating the sample size by outcome type and the hypothesis to be tested, together with the code in the R programming language. We describe four methods for adjusting the original sample size for interim analyses. We sought to introduce these topics in a simple and concrete way, considering the mathematical expressions that support the results and their implementation in available statistical programs; therefore, bringing health students closer to statistics and the use of statistical programs, which are aspects that are rarely considered during their training.

Epidemiological Determinants of Depression among the Geriatric Population Residing in a Slum of Urban India: A Cross-sectional Study

Background: Mental health is important at every stage of life, from childhood and adolescence through adulthood. Worldwide interest in geriatric depression has increased but studies to assess the depression among the elderly population in urban slums has hardly been done. So this study would shed light on the risk factors of depression among geriatrics in urban slums. Aim & Objective: To study the epidemiological determinants such as age, marital status, education, financial dependency, economic status and chronic illness in relation to of depression among the geriatric population (60–80 years). Settings and Design: Community-based, cross-sectional study for 24 months with a samplesize of 209. Methods & Material: Urban slum area represented by one health post was selectedas the study area which caters to around 96,630 slum residents. Pre-tested semi-structuredinterviews were conducted after selecting households by systematic random sampling. Statistical analysis: Data was analyzed using SPSS version 21. A chi-square test was applied. Result: The present study shows overall prevalence of depression among the elderly above 60 years of age to be 48.6%. Depression is found to been significantly associated with an increase in age, living alone (72.7%), lower class economic status (100%), financial dependency (54%), history of chronic family illness (54.7%) and with no formal education (62.1%) among elderly dwelling in slums. Conclusions: There is a high prevalence of depression in the community and hence, a need to sensitize Primary level Health Care Services to institute screening tests considering the association of these determinants with depression and link them to specialized services for further management.

Identifying Pre-hypertensives in the Community: At Risk Approach for Prevention of Hypertension

Introduction: Pre-hypertension is a borderline health state of increased blood pressure (BP) that falls short of the measurable parameters at which surveillance and/or therapy would be required. The approach of identifying people “At Risk” of developing hypertension can be more cost-effective and feasible for applying lifestyle interventions. Objectives: The objective of the present study is to find the prevalence of pre-hypertensives and associated bio-socio-demographic factors Materials and Methods: A cross-sectional study was conducted among 1946 participants aged 19 years and more in the Doiwala block of Dehradun, Uttarakhand. Multistage sampling was used to arrive at desired sample size. A pre-validated, structured questionnaire was used for data collection. The questionnaire included information on the socio-demographic profile (age, sex, education etc.), awareness about hypertension and its associated risk factors. Statistical Analysis: The chi-square test was used to compare proportions and draw inferences. Results: 958 (49.2%) study participants out of a total 1946 were found to be pre-hypertensives. A statistically significant association was found between pre-hypertension and factors such as male gender, age, education, occupation and waist-hip ratio. (p<0.05) Conclusion: It is recommended that identification on the pre-hypertensive group and subjecting them to lifestyle modification could be a fruitful strategy for preventing them from becoming hypertensive.

Use of appropriate statistical tools in biomedical research: Current trend & status

Background & objectives: Due to lack of appropriate statistical knowledge, published research articles contain various errors related to the design, analysis and interpretation of results in the area of biomedical research. If research contains statistical error, however, costly, it may be of no use and the purpose of the investigation gets defeated. Many biomedical research articles published in different peer reviewed journals may retain several statistical errors and flaws in them. This study aimed to examine the trend and status of application of statistics in biomedical research articles. Study design, sample size estimation and statistical measures are crucial components of a study. These points were evaluated in published original research articles to understand the use or misuse of statistical tools. Methods: Three hundred original research articles from the latest issues of selected 37 journals were reviewed. These journals were from the five internationally recognized publication groups (CLINICAL KEY, BMJ Group, WILEY, CAMBRIDGE and OXFORD) accessible through the online library of SGPGI, Lucknow, India. Results: Among articles assessed under present investigation, 85.3 per cent (n=256) were observational, and 14.7 per cent (n=44) were interventional studies. In 93 per cent (n=279) of research articles, sample size estimation was not reproducible. The simple random sampling was encountered rarely in biomedical studies even though none of the articles was adjusted by design effect and, only five articles had used randomized test. The testing of assumption of normality was mentioned in only four studies before applying parametric tests. Interpretation & conclusions: In order to present biomedical research results with reliable and precise estimates based on data, the role of engaging statistical experts need to be appreciated. Journals must have standard rules for reporting study design, sample size and data analysis tools. Careful attention is needed while applying any statistical procedure as, it will not only help readers to trust in the published articles, but also rely on the inferences the published articles draw.

Behavioral Risk Factors of HBV Infection and its Association with HBs Ag Positivity among Residents of Kaza Sub- division of District Lahaul & Spiti in Himachal Pradesh

Background: Chronic viral hepatitis is a major global public health problem, an important cause of morbidity and mortality. We conducted this study to evaluate the behavioral risk factors of HBV infection and its association with HBsAg positivity among residents of Kaza sub-division of district Lahaul & Spiti in Himachal Pradesh. Material & Methods: The study was carried out by the Gastroenterology, Community Medicine, and Microbiology Department at Indira Gandhi Medical College Shimla at Kaza, a subdivision of Lahaul & Spiti. The cluster sampling technique was used to get the desired sample size of 4000. Forty clusters were chosen using a probability proportionate to size sampling method, and 100 research participants were added to each cluster using a simple random sampling method. The data was gathered using a pre-tested interview plan. A blood sample of 5ml from each study participant was obtained, and its HBsAg content was examined. Results: In our study, 2.7% of the interviewed respondents’ parents were positive for hepatitis B and 3.7% reported one positive family member. Injectable drug use was reported by 1.6 (68/4231). Among these users 8.8% (6/68) shared needles with other IDUs in last 12 months and 35.3% (24/68) used a common container to draw up drug solution. Sexual intercourse was reported to be experienced by 15.5 (655/4231) and 12.2% either did not disclose or were children. Out of those who ever experienced sexual/penetrative intercourse 38.3% (251/655) had reported it with someone else other than a spouse. Majority of these had two partners other than a spouse (30.3%; 76/251). Around 30% (195/655) reported of using a condom in their last intercourse. Body piercings or a tattoo from someone who doesn’t sterilize his or her equipment, including local treatment from lamas, was prevalent among 16.3% of the population (689/4231). Acupuncture was taken as a remedy for any medical condition by 9% of participants. Regression analysis also revealed that one infected family member emerged as an independent factor associated with HBsAg positive test after adjusting for confounders. Conclusion: Our study provided much important information concerning hepatitis B risk factors in this tribal group. Health education about behavioral risk factors among this tribal population should be the main intervention that might help limit the spread of these blood-borne infections.

Association of Dietary and Physical Activity Patterns and Hypertension in Western Rajasthan, 2022

Introduction: Hypertension (HTN) is a modifiable risk factor for coronary artery disease, heart failure, cerebrovascular disease and chronic renal failure. HTN affects about 1 billion people globally; by 2025, up to 1.58 billion adults worldwide are likely to suffer from complications of HTN. This study was done to know the diet and physical activity patterns and HTN among the population of three districts of Western Rajasthan. Objectives: To study the dietary and physical activity patterns among the population of Western Rajasthan. and to compare key findings among three districts Pali, Jodhpur and Barmer so that lifestyle changes can be recommended. Methods: A case-control study was done among attendees of NCD clinics of tertiary-level centers in Pali, Barmer and Jodhpur. Hospital Controls were matched to age (± 5 years) and gender Considering the prevalence of HTN to be 20%*, the proportion of exposure in the general population as 0.2, odds ratio to be 2.2, power =80%, alpha=5% sample size is estimated to be 102 cases & 102 controls (from each district). Results: Overall being married (OR= 3.3), having diabetes Cardiac disease (OR= 2.6), excessive salt consumption (OR= 2.7), moderate physical exercise less than 30 minutes (OR=1.9), using oil other than vegetable oil(OR=1.8) , Age >?60 years (OR =1.4) were the key risk factors. It was found that high BMI (BMI>27), consumption of non-vegetable oils (12.7%) was highest in Jodhpur, lack of moderate exercise for at least 30 minutes (81%), lack of sports activity (92%) was highest in Pali, least number of days/week of fruits and vegetables consumption (~1.64 days) was seen in Barmer. Conclusions: Change in quantity of salt consumption and incorporation of moderate physical exercise for >30 minutes was most followed in control of HTN among the attendees of NCD Clinics from the multiple advise given.

Knowledge, Attitude and Practices Regarding Electronic Waste (e-waste) Management Among Users of Electronic Equipments Living in Lucknow City

Background: Contemporary society has led to the increasing use of electronic equipment that is very much responsible for the burden of electronic waste (e-waste). E-waste contains very hazardous substance that harms health and environmental conditions. There is no delicate mechanism for the management of e-waste in Lucknow city, Uttar Pradesh. This study assessed knowledge, practice, and awareness of e-waste management among residents of this city. Material and methods: The study was conducted amongst users of electronic equipment living in the Lucknow City of Uttar Pradesh. The study was a cross-sectional descriptive study. Multi-stage random sampling was done for the selection of participants for the study. A predesigned and pretested questionnaire was administered in a single setting for all phases. The total optimum sample size is 700 individuals who participated in the study. Data were entered in MS Excel 2016 and descriptive statistics such as frequencies and percentages were calculated, applying the chi-square test for association using R-4.2.1 Statistical software. Aim and objectives: To assess the knowledge, attitude and practices regarding the management of electronic waste among users of electronic equipment residing in Lucknow city. Results: Only 37% of users are aware that e-waste adversely affects health. Only 34.3% of users knew that e-waste should be given to the seller or manufacturer for recycling while rest told that it should be stored at home, sold to a scrap dealer, or disposed with normal waste. 87.3% users are not aware about e-waste govt guidelines. In the current study electronic and print media like television, radio and news paper were not found to be source of information for e-waste disposal. Conclusion: Education regarding the ill effects of e-waste is essential for people and awareness of proper disposal of e-waste is the need of the hour. Electronic and print media as well as companies producing electronic equipment should play a significant role to awaken the respondent about the disposal of e-waste

Comparison of 7 methods for sample size determination based on confidence interval estimation for a single proportion / 南方医科大学学报

OBJECTIVE@#To compare different methods for calculating sample size based on confidence interval estimation for a single proportion with different event incidences and precisions.@*METHODS@#We compared 7 methods, namely Wald, AgrestiCoull add z2, Agresti-Coull add 4, Wilson Score, Clopper-Pearson, Mid-p, and Jefferys, for confidence interval estimation for a single proportion. The sample size was calculated using the search method with different parameter settings (proportion of specified events and half width of the confidence interval [ω=0.05, 0.1]). With Monte Carlo simulation, the estimated sample size was used to simulate and compare the width of the confidence interval, the coverage of the confidence interval and the ratio of the noncoverage probability.@*RESULTS@#For a high accuracy requirement (ω =0.05), the Mid-p method and Clopper Pearson method performed better when the incidence of events was low (P < 0.15). In other settings, the performance of the 7 methods did not differ significantly except for a poor symmetry of the Wald method. In the setting of ω=0.1 with a very low p (0.01-0.05), failure of iteration occurred with nearly all the methods except for the Clopper-Pearson method.@*CONCLUSION@#Different sample size determination methods based on confidence interval estimation should be selected for single proportions with different parameter settings.

Método de captura y recaptura: una experiencia de su aplicación para determinar la incidencia de diabetes gestacional / Capture and recapture method: anexperience of itsapplication to estimatetheincidence of gestational diabetes

Los métodos de captura y recaptura (MCR) se emplean en la estimación de poblaciones mediante la utilización de diferentes fuentes de datos, disponibles e incompletas, que registran por separado un mismo evento. En esta metodología, las fuentes son utilizadas para extrapolar el número de individuos no registrados, usando la información recopilada sobre los individuos sí registrados. Este artículo describe todos los pasos de su aplicación práctica, a partir de un ejemplo de estimación de la incidencia de diabetes gestacional en una institución, a partir de cinco fuentes documentales. (AU)

Capture-recapture (CRM) methods are widely used to estimate populations by using different data sources, available and incomplete, that record the same event separately. In these methods, the available sources are used to extrapolate the number of unregistered individuals, using the information collected on the individuals that are registered. This article describes all the steps of its practical application, based on an example of estimating the incidence of gestational diabetes in an institution based on five documentary sources. (AU)

PSS Health: como calcular tamanho de amostra para testes de comparação de médias de dois grupos / PSS Health: how to calculate sample sizes for mean comparison tests between two groups

Dando continuidade à série de artigos que pretendem orientar o usuário na utilização da ferramenta PSS Health para o planejamento de uma pesquisa, esta edição apresenta um passo a passo de como realizar o cálculo e de quais informações são necessárias para comparar médias: de dois grupos dependentes ou independentes, de dois grupos independentes com duas medidas repetidas (deltas), e com duas ou mais medidas repetidas. Todos os exemplos também são ilustrados e disponibilizados em vídeos no canal da Unidade de Bioestatística.

Following the series of articles aiming to guide users in using the PSS Health tool for research planning, this issue presents a step-by-step guide on how to calculate and what information is needed to compare means between 2 dependent or independent groups, 2 independent groups with 2 repeated measures (deltas), and 2 independent groups with 2 or more repeated measures. All examples are accompanied by figures and available in video on the Biostatistics Unit's channel.

PSS Health: como calcular tamanho de amostra para testar relações de variáveis com um desfecho binário / PSS Health: how to calculate the sample size to test variables relationships with a binary outcome

Dando continuidade à série de artigos que pretendem orientar o usuário na utilização da ferramenta PSS Health para o planejamento de uma pesquisa, esta edição apresenta um passo a passo de como realizar o cálculo para tamanho de amostra e de quais informações são necessárias para testar relações estatísticas entre variáveis e um desfecho binário: comparação de proporções entre grupos independentes (dois ou mais), comparação de duas proporções dependentes e regressão logística. Todos os exemplos também são ilustrados e disponibilizados em vídeos no canal da Unidade de Bioestatística.

Following the series of articles that aim to guide the user in using the PSS Health tool for planning research, this issue presents a step-by-step guide on how to perform the sample size calculation and what information is needed to test statistical relationships between variables and a binary outcome: comparison of proportions between independent groups (two or more), comparison of two dependent proportions, and logistic regression. All examples are also illustrated and available in videos on the Biostatistics Unit's channel.

Impacto sobre el tamaño de las muestras en estudios nacionales si cambiara el nivel de significación estadística de α= 0,05 a α = 0,005

Background: The statistical significance α = 0.05 is the cut-off point used to decide whether a hypothesis is statistically significant. When p-value is less than 0.05, we reject the null hypothesis. Although this criterion has been used for almost a century to generate new knowledge, there is currently an international discussion about the need to decrease the significance to α = 0.005. Aim: To determine the effects that changing the p value would have on the sample size of different types of studies. Material and Methods: A series of formulas for calculating the sample size of cross-sectional and comparative studies were used to create case scenarios. Results: By changing α = 0.05 to α = 0.005, the sample sizes in cross-sectional studies would double and in comparative studies would increase between 60% and 70%, depending on the statistical power chosen. Conclusions: Considering the sample size implications, the change in the level of significance would have important effects on the Chilean science. The cost of a randomized clinical trial could increase by at least 27% to 32%. This increase could be similar for cross-sectional studies. With an investment of less than 0.4% of gross domestic product in science and technology, national scientific research would become more expensive, distributing the few available resources among fewer projects. This effect should be considered in any discussion about national budget for science and technology.

PSS Health: como calcular tamanho de amostra para estimar média, proporção e correlação / PSS Health: how to calculate a sample size to estimate means, proportions, and correlations

A ferramenta PSS Health (Power and Sample Size for Health Researchers) foi desenvolvida com o propósito de facilitar o cálculo do tamanho amostral e do poder de testes de hipóteses para diferentes objetivos de estudo, usando interface amigável e terminologia comum à área da saúde. Este é o primeiro de uma série de artigos que pretendem orientar o usuário na utilização da ferramenta PSS Health para o planejamento de uma pesquisa. Neste artigo, se ensina como utilizar o PSS Health quando o objetivo principal do estudo é estimar uma média, estimar uma proporção (prevalência ou incidência) ou estimar uma correlação. São disponibilizados vídeos demonstrando o uso da ferramenta em cada um dos contextos citados. (AU)

The PSS Health (Power and Sample Size for Health Researchers) tool was developed with the purpose of facilitating the calculation of sample size and power of hypothesis tests for different study objectives, based on a user-friendly interface and common health care terminology. This is the first in a series of articles intending to guide the user in how to use the PSS Health tool for planning a research project. This article teaches how to use PSS Health when the main objective of the study is to estimate means, proportions (prevalence or incidence), or correlations. Videos showing how to use the tool in each of the mentioned contexts are available. (AU)

Sample size estimation in acupuncture and moxibustion clinical trials / 中国针灸

The appropriate sample size estimation is very important in the design of clinical trials. However, insufficient or inappropriate sample size estimation is still a prominent problem in the currently published acupuncture and moxibustion clinical trials. At present, the superiority test, non-inferiority test and equivalence test have been widely used in acupuncture and moxibustion clinical trials. This article focuses on the application, calculation methods and PASS11 software using of these three hypothesis test types. In view of the problems in the estimation of sample size in acupuncture and moxibustion clinical trials, the particularity of sample size estimation in acupuncture and moxibustion is summarized from the aspects of parameter setting, ratio of intervention group and control group, and multi-group comparison, in order to guide acupuncture clinical researchers to correctly estimate sample size when conducting clinical trials.

Algunas consideraciones para el cálculo del tamaño muestral en investigaciones de las Ciencias Médicas / Some considerations for the calculation of the sample size in Medical Sciences research

RESUMEN El proceso de formación y superación permanente o continuada de los profesionales, como un principio de la Educación Médica, se articula con la integración docencia, asistencia e investigación. Para responder a las exigencias de la actividad investigativa, la búsqueda y el tratamiento de la información requiere de un estudio estadístico para que aflore la cualidad desde el análisis cuantitativo; para ello, es importante considerar que en todos los estudios de esta magnitud, la población total se hace muy engorrosa, cara y lenta, por lo que se deben emplear técnicas de muestreo para obtener información significativa con el uso de menos recursos y menor tiempo. El objetivo del presente trabajo es reflexionar sobre el uso del muestreo en las ciencias médicas. Se expone la fórmula del muestreo para media y varianza conocidas, se da una técnica para encontrar el número de elementos de la muestra inicial cuando no se tienen conocimientos previos de media y varianza; se estudia el muestreo aleatorio simple de proporciones con las probabilidades de éxito y fracaso p y q respectivamente, explicándose el caso cuando se tiene p = q = 0.5 para la obtención de un tamaño de la muestra máximo.

ABSTRACT The objective of this paper is to reflect some considerations on the use of sampling in health sciences, based on the need for professionals in these sciences to familiarize themselves with scientific research in their area of knowledge, from a scientific perspective, that makes it possible to investigate the health problems that are constantly developing. The process of Permanent and Continuous Training and Improvement of professionals, as a principle of Medical Education, is articulated with that of Teaching - Assistance and research, the search and treatment of information in this area of scientific knowledge, requires of a statistical study that emerges the quality from the quantitative analysis, for this, it is important to consider that in all studies of this magnitude, the total population becomes very cumbersome, expensive and slow, so sampling techniques should be used to Obtain meaningful information with the use of less resources and less time. The sampling formula for known mean and variance is presented, a technique is given to find the number of elements of the initial sample when there is no prior knowledge of mean and variance, simple random sampling of proportions with the probabilities of success is studied and failure p and q respectively, explaining the case when you have p = q = 0.5 to obtain a maximum sample size.

A terapia por vibração do corpo inteiro promove melhora do equilíbrio na doença de Parkinson? / Does whole body vibration improve balance in Parkinson's disease?

Distúrbios do equilíbrio consistem em um grande problema na doença de Parkinson (DP). A terapia por vibração do corpo inteiro mostra-se benéfica em pessoas saudáveis, mas apresenta eficácia incerta na DP. O objetivo desse estudo foi verificar os efeitos agudos da terapia por vibração do corpo inteiro sobre o equilíbrio de pacientes com DP e analisar o tamanho do efeito da intervenção para predizer o número ideal de participantes. Doze participantes com DP foram randomicamente divididos entre grupos intervenção e placebo. O grupo intervenção foi submetidos à terapia vibratória, tendo o equilíbrio avaliado em período anterior, imediatamente após e transcorrido cinco minutos da sessão. O grupo placebo fez uma intervenção simulada, tendo o equilíbrio avaliado nos mesmos períodos. Ambos os grupos tiveram seus olhos vendados para manter cegamento dos participantes sobre a intervenção. As variáveis analisadas foram deslocamento, área e velocidade de deslocamento. O tamanho do efeito foi verificado em análises univariadas e multivariadas, admitindo significância em 5%. Sobre os resultados, a terapia por vibração do corpo inteiro não apresentou eficácia sobre o equilíbrio na DP em momento imediato e transcorrido cinco minutos da aplicação da terapia. A análise que apresentou maior tamanho do efeito se deu quando o equilíbrio foi mensurado de forma multivariada, predizendo a necessidade de 46 pacientes. Em conclusão, os resultados desse estudo foram imprecisos quanto à eficácia da terapia por vibração do corpo inteiro no equilíbrio de pacientes com DP. Novas pesquisas com uma amostra superior a 46 participantes devem ser realizadas

Balance disorders are a major problem in Parkinson's disease (PD). The whole body vibration has benefits on the balance in healthy people, but it has imprecise effectiveness in PD. The aim of this study was to verify the effects of whole body vibration on balance in patients with PD and to predict the ideal number of participants from the effects size. Twelve participants with PD were randomly divided into intervention and placebo groups. Participants in the intervention group underwent whole body vibration and the subjects had their balance assessed prior therapy, immediately and five minutes after the session. The control group underwent a placebo intervention and the subjects had their balance assessed on the same periods. Both groups had their eyes closed during the intervention protocol. The variables assessed were body displacement, area and velocity of body displacement. The effect size of the intervention was analysed under univariate and multivariate analyses. Significance was set at 5%. With respect to the results, the whole body vibration was inefficient in improving balance immediately and five minutes after the session. The analysis that presented the strongest effect size occurred when balance was assessed under a multivariate basis, predicting the need of 46 participants. In conclusion, the results were imprecise as to the effects of whole body vibration on the balance in patients with PD. Studies with a sample size higher than 46 participants should be carried out to further address this topic

Metodologías cuantitativas: Cálculo del tamaño de muestra con STATA y R / Quantitative methods: Sample size calculation with STATA and R

El cálculo de tamaño de muestra es un aspecto esencial del diseño de estudios cuantitativos. Un adecuado tamaño de muestra nos permite determinar cuál es la mínima cantidad de participantes necesarios para probar nuestra hipótesis de interés. De esta manera, podemos reducir costos, maximizar el uso de nuestros recursos de investigación y garantizar la factibilidad del estudio. Contradictoriamente, a pesar de su relevancia muy pocos investigadores dominan esta habilidad. Esta revisión tiene por objeto revisar los conceptos básicos para realizar un cálculo de tamaño de muestra y compartir códigos de Stata y R específicamente diseñados para facilitar estos cálculos.

The calculation of sample size is an essential aspect of the design of quantitative studies. An adequate sample size allows us to determine the minimum number of participants necessary to test our hypothesis of interest. Hence, we can reduce costs, maximize the use of our research resources and guarantee the feasibility of the study. Contradictorily, despite its relevance, very few researchers dominate this skill. This review aims to review the basics of sample size calculation and share Stata and R codes specifically designed to facilitate these calculations.

Pesquisa Nacional de Saúde 2019: histórico, métodos e perspectivas / Encuesta Nacional de Salud 2019: historia, métodos y perspectivas / National Health Survey 2019: history, methods and perspectives

Este artigo apresenta o histórico e a construção da Pesquisa Nacional de Saúde (PNS) 2019, inquérito de base domiciliar realizado em parceria com o Instituto Brasileiro de Geografia e Estatística. O objetivo da PNS 2019 foi dotar o país de informações sobre os determinantes, condicionantes e necessidades de saúde da população brasileira. A amostra prevista foi de 108.525 domicílios particulares, considerando-se uma taxa de não resposta de 20%. Seu questionário continha três partes, orientadas para (i) o domicílio, (ii) todos os moradores do domicílio, com enfoque na coleta de informações socioeconômicas e de saúde, e (iii) o morador selecionado (idade ≥15 anos), sendo investigados estilos de vida, doenças crônicas, violências, entre outros temas, e aferidas medidas antropométricas (subamostra). As informações da PNS 2019 servirão de base para a (re)formulação de políticas de saúde e subsídio a ações e programas existentes do Sistema Único de Saúde.

Este artículo presenta la historia y la construcción de la Encuesta Nacional de Salud (PNS) 2019, una encuesta domiciliaria realizada en colaboración con el Instituto Brasileño de Geografía y Estadística. El objetivo de la PNS fue proporcionar al país información sobre los determinantes, las condiciones y las necesidades de salud de la población brasileña. La muestra esperada fue de 108.525 hogares particulares, considerando una tasa de no respuesta del 20%. Su cuestionario contenía tres partes: (i) con respecto al hogar; (ii) dirigido a todos los residentes, centrándose en la recopilación de información socioeconómica y de salud; y (iii) al residente seleccionado (15 años o más) de quien se investigó estilos de vida, enfermedades crónicas, violencia, entre otros temas y se compararon las medidas antropométricas (submuestra). La información de la PNS 2019 servirá como base para la (re)formulación de políticas de salud y para apoyar acciones y programas existentes en el Sistema Único de Salud.

This article presents the history and construction of the National Health Survey (PNS) 2019, a household survey conducted in partnership with the Brazilian Institute of Geography and Statistics. The objective of PNS 2019 was to provide the country with information on the health determinants, conditionants and needs of the Brazilian population. The expected sample was 108,525 households, considering a 20% non-response rate. The questionnaire had three parts, covering: (i) the household; (ii) all residents of the household, focusing on collection of socioeconomic and health information; and (iii) the selected resident (15 years old or more) for whom lifestyles, chronic diseases, violence, among other topics were investigated, as well as their anthropometric measurements (subsample). The information provided by PNS 2019 will serve as a basis for the (re)formulation of health policies, as well as support for existing actions and programs of the Brazilian National Health System.

Teratoma quístico maduro con transformación maligna: serie de casos / Cystic teratoma with malignant transformation: Series of cases

Resumen OBJETIVO: Describir las características clínicas e histopatológicas de los casos de teratoma maduro con transformación maligna, su tratamiento y supervivencia. MATERIALES Y MÉTODOS: Estudio retrospectivo, transversal y observacional efectuado entre enero de 2014 y diciembre de 2018 en un servicio de oncología ginecológica. Parámetros de estudio: etapa patológica del tumor, concentraciones de Ca 125, supervivencia y tratamiento. El tamaño de la muestra no permitió aplicar pruebas estadísticas. RESULTADOS: Se estudiaron 147 pacientes con diagnóstico de teratoma maduro, de éstos 4 experimentaron transformación maligna a carcinoma epidermoide y se descartaron 18 por información incompleta. El estudio histopatológico transoperatorio identificó malignidad en 3 de los 4 tumores de ovario. No se practicaron cirugías conservadoras de la fertilidad porque en ninguno de los casos fue necesaria. En 3 de los 4 teratomas maduros con transformación maligna se indicó esquema de quimioterapia coadyuvante. Todas las pacientes permanecen vivas y sin recaída hasta el momento. CONCLUSIONES: El estudio histopatológico transoperatorio es indispensable en todas las lesiones de ovario, incluso las de aspecto quístico. El tratamiento quirúrgico cuidadoso de los tumores malignos de ovario evita su ruptura y cambio en el pronóstico y tratamiento de las pacientes. El tratamiento quirúrgico y médico de una neoplasia poco frecuente, como el teratoma maduro con transformación maligna, mejora la supervivencia y evita subtratamientos o sobretratamientos.

Abstract OBJECTIVE: Describe the clinical and histopathological characteristics of cases of mature teratoma with malignant transformation, its treatment and survival. MATERIALS AND METHODS: Retrospective, cross-sectional and observational study conducted between January 2014 and December 2018 in a gynecological oncology service. Study parameters: pathological stage of the tumor, concentrations of Ca 125, survival and treatment. The sample size did not allow statistical tests to be applied. RESULTS: 147 patients with a diagnosis of mature teratoma were studied of these 4 underwent malignant transformation to squamous cell carcinoma and 18 were ruled out due to incomplete information. The transoperative histopathological study identified 3 of the 4 ovarian tumors as malignant. Fertility conservative surgeries were not performed because in none of the cases was it necessary. In 3 of the 4 mature teratomas with malignant transformation, adjuvant chemotherapy scheme was indicated. All patients remain alive and have no relapse so far. CONCLUSIONS: The histopathological transoperatory study is absolutely necessary for an ovarian tumor, even in cystic ovarian tumors. Carefully management of ovarian tumors is very important, we should prevent a rupture of the malignant tumor because this changes the surgical stage and the prognosis. The surgical and medical treatment of infrequent tumor-like mature teratoma with malignant transformation improves survival and avoid sub treatments or overtreatment.