Conceptos básicos del metaanálisis en red

ResumenLas revisiones sistemáticas y los metaanálisis se han consolidado como una herramienta fundamental para la práctica clínica basada en la evidencia. Inicialmente, el metaanálisis fue propuesto como una técnica que podría mejorar la precisión y la potencia estadística de la investigación procedente de estudios individuales con pequeño tamaño muestral. Sin embargo, uno de sus principales inconvenientes es que suelen comparar no más de 2 intervenciones alternativas a la vez. Los «metaanálisis en red» utilizan técnicas novedosas de análisis que permiten incorporar la información procedente de comparaciones directas e indirectas a partir de una red de estudios que examina los efectos de diversos tratamientos de una manera más completa. Pese a sus potenciales limitaciones, su aplicación en epidemiología clínica podría ser potencialmente útil en situaciones en las que existen varios tratamientos que se han comparado frente a un comparador común.Además, estas técnicas pueden ser relevantes ante una pregunta clínica o de investigación cuando existen múltiples tratamientos que deben ser considerados, o cuando se dispone tanto de información directa como indirecta en el cuerpo de la evidencia.AbstractSystematic reviews and meta-analyses have long been fundamental tools for evidence-based clinical practice. Initially, meta-analyses were proposed as a technique that could improve the accuracy and the statistical power of previous research from individual studies with small sample size. However, one of its main limitations has been the fact of being able to compare no more than two treatments in an analysis, even when the clinical research question necessitates that we compare multiple interventions. Network meta-analysis (NMA) uses novel statistical methods that incorporate information from both direct and indirect treatment comparisons in a network of studies examining the effects of various competing treatments, estimating comparisons between many treatments in a single analysis. Despite its potential limitations, NMA applications in clinical epidemiology can be of great value in situations where there are several treatments that have been compared against a common comparator. Also, NMA can be relevant to a research or clinical question when many treatments must be considered or when there is a mix of both direct and indirect information in the body of evidence

Influence of Diagnostic Delay on Survival Rates for Patients with Colorectal Cancer

Colorectal cancer affects men and women alike. Sometimes, due to clinical-pathological factors, the absence of symptoms or the failure to conduct screening tests, its diagnosis may be delayed. However, it has not been conclusively shown that such a delay, especially when attributable to the health system, affects survival. The aim of the present study is to evaluate the overall survival rate of patients with a delayed diagnosis of colorectal cancer. This observational, prospective, multicenter study was conducted at 22 public hospitals located in nine Spanish provinces. For this analysis, 1688 patients with complete information in essential variables were included. The association between diagnostic delay and overall survival at five years, stratified according to tumor location, was estimated by the Kaplan-Meier method. Hazard ratios for this association were estimated using multivariable Cox regression models. The diagnostic delay ≥ 30 days was presented in 944 patients. The presence of a diagnostic delay of more than 30 days was not associated with a worse prognosis, contrary to a delay of less than 30 days (HR: 0.76, 0.64-0.90). In the multivariate analysis, a short delay maintained its predictive value (HR: 0.80, 0.66-0.98) regardless of age, BMI, Charlson index or TNM stage. A diagnostic delay of less than 30 days is an independent factor for short survival in patients with CRC. This association may arise because the clinical management of tumors with severe clinical characteristics and with a poorer prognosis are generally conducted more quickly.This study was supported by public grants from Instituto de Salud Carlos III (PI09/90397, PS09/00314, PS09/00746, PI09/90453, PI09/00910, PI09/90460, PI09/90490, PI13/01692, PI13/00013, PI18/01181, PI18/01589, PS0900805 & PI0900441) and was co-funded by the European Regional Development Fund.S