¿Qué es una variable de confusión?

Fracture-related infection (FRI) is a common complication following open tibia fracture (OTF), especially in patients with high-energy trauma or comorbidities. The use of gentamicin-coated nail (GCN) has been proposed as a local adjuvant to prevent FRI in high-risk patients.

Hypothesis: The incidence of FRI is expected to be lower in OTF treated with a GCN, alongside with no detrimental effects on fracture healing time.

Objectives: This study aimed to evaluate the effectiveness of GCNs as a definitive fixation method and prophylaxis for FRI in OTFs. Secondary outcomes included non-union rates and time to healing.

Methods: The study design was a mixed cohort, including a prospective group of patients treated with GCN (Expert Tibial Nail PROtect™, Depuy Synthes, Johnson&Johnson Company Inc, New Jersey, USA) and a retrospectively evaluated group treated with non-gentamicin-coated nail (NGCN). Patients with at least 12 months of follow-up were included. The treatment protocol consisted of timely administration of antibiotics, surgical debridement, and early soft-tissue coverage. Exclusion criteria included protocol infringement, traumatic amputation, and loss of follow-up.

Statistical analysis was performed using Stata v14.0, with a significance level of p < 0.05.

Results: The study included 243 patients, 104 in GCN group and 139 NGCN group. External Fixator use was higher in the NGCN group, but this did not significantly affect the FRI rate.

GCN use was associated with a significantly lower incidence of FRI (2.88% GCN group vs. 15.83% NGCN group, OR 0.16, p < 0.01). Furthermore, GCN use was found to be a protective factor against tibial non-union (OR 0.41, p = 0.03). There were no adverse effects attributed to locally administered gentamycin. The NGCN cohort had a higher incidence of polytrauma, although the difference was not statistically significant. A longer time to heal as well as more FRI and Non-union according to the progression in Gustilo-Anderson classification was observed in the GCN group.

Conclusion: Our findings suggest that GCN is an effective prophylactic method to reduce the risk of FRI in open tibial fractures at 12-month follow-up, as well as, probably derived from this protective effect, leading to lower fracture consolidation times when compared with cases treated without GCN.

The analysis of foster care placements that have already ended allows us to study them from the perspective of their outcomes, while revealing the distinguishing elements that contribute to our understanding. The objectives of this study were: (a) to identify the rate of placement breakdown, understood as the unplanned termination of a foster placement; (b) to explore the variables associated with foster placement termination, and finally (c) to determine to what extent each variable can explain placement breakdown. This study was conducted on 1255 cases closed between 2008 and 2018 in Spain. With a quantitative approach, eight organizations provided information on 100% of their cases and 5 organizations followed a random selection procedure. Data were analyzed based on bi- and multivariate data analysis, with the construction of a logistic regression model. Findings suggest the relevance of variables such as placement type, the child’s age, length of stay in foster care, pathways before entering and within the protection system, type of abuse, characteristics of the foster family, and the relationship with the birth family. Breakdown occurs for reasons that are not only subject to behavioural issues or other characteristics of the child, but rather to a set of inter-related factors at different levels (family and system variables). These findings are intended to enhance professional practice and public policy-making.

Hox genes are involved in limb formation during normal embryological development. Their modulation by circulating maternal oestrogens and androgens determines the length of the second and fourth fingers of the adult hand. Do these same intrauterine hormone levels also determine fertility outcomes in the adult?

To study the association between the length of the second and fourth fingers of both partners undergoing IVF (as a surrogate of their previous intrauterine exposure to oestrogens and androgens) with treatment outcome after IVF, data corresponding to 256 IVF cycles were analysed. Finger length was normalized to the individual height.

In the female partner, a longer normalized second finger length of the left (2DLN) hand, reflecting a high intrauterine exposure to oestrogens, was independently and significantly (P = 0.011) associated with obtaining at least one top-quality embryo in a multivariate model. Conversely, in the male partner a longer normalized fourth finger length of the left hand (4DLN), reflecting a high intrauterine exposure to androgens, was independently and significantly (P = 0.032) associated with obtaining at least one top-quality embryo in the same multivariate model. In the female partner, 2DLN was inversely and significantly (P = 0.01) associated with achievement of pregnancy.

Intrauterine exposure to high levels of oestrogens and androgens in females and males, respectively, predisposes to the production of higher-quality embryos under in-vitro conditions during adulthood. Paradoxically, this also seems to result in a lower pregnancy rate.

Systematic error, or bias, is error that occurs in each measurement made and which has a direction, i.e., the measured value is always either greater or smaller than the true value. The presence of systematic error directly affects the internal validity of the study, and indirectly affects the external validity of the results obtained. In general, such error can be classified as selection bias, classification bias or confounding bias.

It is essential to deal with possible bias in the research design phase, since only confounding bias can be controlled in the phase corresponding to analysis of the results.

Aunque se han encontrado asociaciones entre el consumo de cannabis y la conducta suicida en población adulta y adolescente, dichas asociaciones se ven interferidas por numerosos factores de confusión, que no se incluyen, en su mayoría, en los estudios y que podrían explicar gran parte de las asociaciones referidas. Parece improbable que el consumo de cannabis actúe como factor causal directo de suicidio consumado. Pero en cambio el consumo de cannabis sí podría actuar como factor causal indirecto de suicidio al generar o favorecer otras situaciones (como el consumo de otras sustancias adictivas o la aparición de morbilidad psiquiátrica o física) que directamente incrementarían el riesgo de suicidio. En concreto, la exposición al cannabis en sujetos con algún tipo de alteración neurobiológica en su sistema endocannabinoide que estarían predispuestos al consumo de otras sustancias adictivas (como el alcohol) o al desarrollo de patología psiquiátrica (psicótica o afectiva) que incrementarían el riesgo de suicidio. Se hacen, pues, necesarios más estudios, especialmente prospectivos, que permitan determinar si realmente hay una asociación y si hay indicios de causalidad.

Although previous studies have found associations between cannabis use and suicidal conduct in adult and in adolescent populations, these associations are hampered by several confounding factors that are largely unaddressed by researchers and might explain such associations to a great extent. It is improbable that cannabis use is a direct causal factor of consumed suicide. Cannabis use may, however, act as an indirect causal factor of suicide by generating or favoring other situations (for instance, the use of other addictive substances or the appearance of psychiatric or physical morbidity) that directly increase suicide risk. Specifically, exposure to cannabis among subjects with some sort of neurobiological alteration in the endocannabinoid system could predispose these individuals to the use of other addictive substances (such as alcohol) or the development of psychiatric pathology (psychotic or affective) that would increase the risk of suicide. Further studies, particularly prospective ones, are therefore needed to clarify whether there is indeed an association and if there are indications of causality.

This is a guide for grant application for researchers seeking research grants in the field of allergy and related diseases for the first time. It outlines how to organize proposals and the potential issues to be considered in order to fulfil the criteria of the funding bodies and thus improve chances of obtaining the desired funding when applying for a research grant. We will use this paper as an example of a grant proposal to be presented to the FIS “Fondo de Investigación Sanitaria” (Health Research Fund) of Spain. The general framework can be used for a research proposal to any funding agency. The main research designs are reviewed. Other topics such as hypothesis, objectives, methodology, ethics and legal issues, and budget are presented.