[Cognitive function groups in older people and risk factors].

Background: Risk stratification for cognitive impairment in communities originated from autopsies in cognitively healthy individuals. The Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) incorporates subjective and objective cognitive function (CF) measures to explore neurocognitive disorders (NCD). It can be applied in communities to explore the factors that may influence positively or negatively.

[Methodology for the elaboration of prognosis studies].

Prognostic studies are investigations to estimate the risk or probability of future outcomes in people with established disease. Ideally based on cohort studies where it is established: the time of onset or analysis of the evolution of a disease, the follow-up period for the outcome of interest, the type of outcome and the prognostic factors or markers to investigate. Ultimately, the decision on how to run and analyze forecast studies will depend on their purpose: exploratory, explanatory, or predictive.

Efficiency and Safety of CyberKnife Robotic Radiosurgery in the Multimodal Management of Patients with Acromegaly.

Objective: To analyze, in a cohort of acromegalic patients, the results of the efficiency and safety of radiosurgery (CyberKnife), as well as the prognostic factors associated with disease remission.

Material And Methods: Observational, retrospective, longitudinal, and analytical study that included acromegalic patients with persistent biochemical activity after initial medical-surgical treatment, who received treatment with CyberKnife radiosurgery. GH and IGF-1 levels at baseline after one year and at the end of follow-up were evaluated.

Risk Factors Associated with Mortality among Patients with COVID-19: Analysis of a Cohort of 1213 Patients in a Tertiary Healthcare Center.

The presence of cardio-metabolic and respiratory comorbidities, immunosuppression, and chronic kidney disease have been associated with an increase in mortality from COVID-19. The objective of this study is to establish the risk factors associated with 30-day mortality in a cohort of hospitalized patients with COVID-19. This paper conducts a retrospective and analytical study of patients hospitalized for COVID-19 in a tertiary care center.

Differential fetal growth rates mediated by sociodemographic factors in Yucatan, Mexico: an epidemiological study.

Background: Fetal growth restriction (FGR) may be related to ethnicity. Additionally, ethnic groups experience adverse socioeconomic circumstances that increase FGR risk. However, the dearth of evidence of the interaction between socioeconomic factors and FGR highlights the need for additional research.

Risk factors associated with thyroid nodular disease in acromegalic patients: A case-cohort study in a tertiary center.

Introduction: Goiter is very common in patients with acromegaly; its development is correlated to the duration of the disease. Thyroid cells express the IGF-1 receptor and the TSH/IGF-1 interaction has been demonstrated to have a synergistic effect in thyroid cell growth. There is a correlation between IGF-1 levels and the thyroid volume of patients with acromegaly.

[Statistical methods for effect size analysis].

Informing in the studies about the effect size of an intervention or the impact of the factor(s) about an outcome, allows better decision-making for the application of the results in clinical practice. This article presents different methods to analyze the effect size, which can be through direct or indirect statistical methods. Within the direct methods, there's the difference in means between groups and the difference of absolute or relative frequencies.

[Risk, association, and impact measures in clinical research studies. How to interpret them for their application in medical care].

The practice of evidence-based medicine includes the critical analysis of clinical research studies, and, within it, the interpretation of the results reported. In addition, to statistical data, there are estimators that can help clinicians transfer research findings to routine clinical practice. These estimators are measures of risk, association, and impact.

[Phases to determine the clinical utility of diagnostic tests].

In general, diagnostic tests are the necessary tools to determine the presence or absence of illness, but they can be useful also for excluding other differential conditions, assessing severity, establishing specific treatments, and estimating possible prognosis results. In order to determine how much a new diagnostic test can contribute in the clinical setting, studies with different research designs and populations are required. Since it might be complex to understand the development process of a diagnostic test based on its initial stages, this article synthesizes and gives examples of the four phases that have been proposed to define this process.

[Biases in diagnostic test studies: impact on estimating sensitivity and specificity].

Diagnostic tests make it possible to determine whether a person has a disease or not. Before incorporating a new diagnostic test in the clinical setting, it is necessary to define its validity through its indicators of performance, sensitivity, and specificity. In these studies, like in any research, the results might not be reliable when there are biases during their execution.

Neurological repercussions of changes in cerebral blood flow in neonates undergoing cardiovascular surgery.

Introduction: Surgery for congenital heart disease can generate cerebral perfusion-associated alterations with neurological repercussions.

Objective: To analyze the relationship of peri-surgical cerebrovascular resistance index (RI) with mediate neurological functions after congenital heart disease surgery.

Method: Prospective cohort study of 34 neonates in whom basilar artery RI, serum oxygen, carbon dioxide and lactate levels were determined before and after palliative or corrective procedures.

Information and Communication Technology, Mobile Devices, and Medical Education.

Information and communication technologies (ICT) are practical and highly available tools. In medical education, ICTs allow physicians to update their knowledge and remember the necessary information within reach of current mobile devices. ICTs as preparation tools for medical education have not been reported for medical students in Mexico.

Non-Hodgkin Lymphoma Epidemiology in Children From 2 Socioeconomic Regions in Mexico: 20-Year Registry (1996-2015).

Purpose: We analyzed the epidemiologic characteristics of different types of non-Hodgkin Lymphoma (NHL), excluding Burkitt Lymphoma, in 2 Mexican regions with different socioeconomic status.

Materials And Methods: In this surveillance study, we analyzed the incidence rates (cases per million children/year) of different types of NHL according to the ICCC3, registered in 1996-2015, from 2 different socioeconomic regions in Mexico: central and southern, with higher and lower status, respectively.

Results: The principal NHL subgroups were precursor (IIb1), mature B cell (IIb2), mature T/NK cell, and no other specification (NOS; 42.

Accuracy of the C-glucose breath test to identify insulin resistance in non-diabetic adults.

Aims: To assess the validity of the C-glucose breath test (C-GBT) to identify insulin resistance (IR) in non-diabetic individuals, using hyperinsulinemic-euglycemic clamps as gold standard. This validity was compared with that of other IR surrogates.

Methodology: Non-diabetic adults were studied in a cross-sectional design.

Importancia del "diagnóstico temprano" en los niños con cáncer para mejorar el pronóstico: concepto con poco sustento científico.

La mortalidad por cáncer en niños mexicanos no ha disminuido a los niveles informados en países desarrollados. Una explicación frecuentemente declarada es el alto porcentaje (57.3 %) de pacientes diagnosticados en estadios avanzados (III/IV), atribuible a errores en la sospecha o en la metodología empleada, consideración dudosa si se toma en cuenta que el tiempo de diagnóstico y la proporción de estadios avanzados en México son semejantes a los de países desarrollados.

[Bayesian analysis. Basic and practical concepts for its interpretation and use].

Bayesian statistics is based on subjective probability. It works with evidence updating considering the knowledge acquired prior to an investigation, plus the evidence obtained thereof. Results' interpretation requires for the hypotheses to be tested to be specified and their a priori probability to be estimated before the study.

Use of Distraction to Reduce Pain in Venipunture when a Venoclysis Is Placed.

The use of a venoclysis in hospitalized pediatric patients is a necessity, a procedure perceived by children as painful, so that distraction techniques have been suggested to attenuate this suffering. Evaluating the implementation of a distraction method with an uncontrolled trial with pre and post maneuver evaluation without control group.

Association Between the Brain-derived Neurotrophic Factor Val66Met Polymorphism and Overweight/Obesity in Pediatric Population.

Background: The brain-derived neurotrophic factor (BDNF) rs6265 (G196A; Val66Met) single nucleotide polymorphism has been associated with BMI and obesity in distinct populations, both adult and pediatric, with contradictory results involving either Val or Met as the risk variant.

Aim Of The Study: To determine the association between the BDNF Val66Met polymorphism and BMI in Mexican children and adolescents.

Methods: BDNF Val66Met genotyping by restriction fragment length polymorphism and nutritional status characterized by their BMI-for-age z-scores (BAZ) from pediatric volunteers (n = 498) were analyzed by Fisher's exact test association analysis.

[Clinical significance vs statistical significance. How to interpret the confidence interval at 95].

The validity of a study depends on its proper planning, execution and analysis. If these are sufficiently correct, the decision to apply the recommendations issued depends on the expected clinical effect. This effect may have random variations, hence the need to use statistical inference.

[The research protocol V: The calculation of sample size].

Sample size refers to the number of participants to be included in a research study. If the calculation is carried out properly, not only conclusions will be established with statistical support and the potential risks to the subjects included in the investigation will be limited, but also the study can be properly planned to optimize economic and time costs. Calculation of sample size requires information that must be supported by the research protocol.

Longitudinal Analysis of the Interaction Between Obesity and Pregnancy on Iron Homeostasis: Role of Hepcidin.

Background And Aims: When pregnancy occurs in obese women, two opposite mechanisms for iron homeostasis concur: increased need for available iron to support erythropoiesis and decreased iron mobilization from diets and stores due to obesity-related inflammation linked to overexpressed hepcidin. Few studies have examined the role of hepcidin on maternal iron homeostasis in the context of obese pregnancy. The aim of the study was to evaluate the combined effect of maternal obesity and pregnancy on hepcidin and maternal iron status while accounting for inflammation and iron supplementation.

Clinical and Epidemiological Characteristics of Burkitt Lymphomas in Pediatric Patients from Two Defined Socioeconomic Regions in Mexico.

We analyzed clinical and epidemiological characteristics of Burkitt lymphoma (BL) in two defined socioeconomic regions in Mexico: high socioeconomic region (HSER; with two political jurisdictions) and low socioeconomic region (LSER; with three jurisdictions). Of the 63 cases registered in the Childhood Cancer Registry (1996-2013), 45 (71.4%) were from HSER and 18 (28.

[Descriptive statistics].

Descriptive statistics is the branch of statistics that gives recommendations on how to summarize clearly and simply research data in tables, figures, charts, or graphs. Before performing a descriptive analysis it is paramount to summarize its goal or goals, and to identify the measurement scales of the different variables recorded in the study. Tables or charts aim to provide timely information on the results of an investigation.

Cancer incidence and mortality in children in the Mexican Social Security Institute (1996-2013).

Objective: To identify the cancer incidence and mortality in Mexican Social Security Institute beneficiary (MSSI-B) children during 1996-2013.

Materials And Methods: Both cancer cases (n=4 728) and deaths (n=2 378) were analyzed in MSSI-B children who were registered in five states of the Mexican Republic. The incidence and mortality trends and the incidences (rate x 1 000 000 children / year) of the type of cancer, age, sex, and place of residence were obtained.