Prognostic effect of high-flux hemodialysis in patients with chronic kidney disease

We investigated the prognostic effects of high-flux hemodialysis (HFHD) and low-flux hemodialysis (LFHD) in patients with chronic kidney disease (CKD). Both an electronic and a manual search were performed based on our rigorous inclusion and exclusion criteria to retrieve high-quality, relevant clinical studies from various scientific literature databases. Comprehensive meta-analysis 2.0 (CMA 2.0) was used for the quantitative analysis. We initially retrieved 227 studies from the database search. Following a multi-step screening process, eight high-quality studies were selected for our meta-analysis. These eight studies included 4967 patients with CKD (2416 patients in the HFHD group, 2551 patients in the LFHD group). The results of our meta-analysis showed that the all-cause death rate in the HFHD group was significantly lower than that in the LFHD group (OR=0.704, 95%CI=0.533-0.929, P=0.013). Additionally, the cardiovascular death rate in the HFHD group was significantly lower than that in the LFHD group (OR=0.731, 95%CI=0.616-0.866, P<0.001). The results of this meta-analysis clearly showed that HFHD decreases all-cause death and cardiovascular death rates in patients with CKD and that HFHD can therefore be implemented as one of the first therapy choices for CKD.

Validity of Qualis database as a predictor of evidence hierarchy and risk of bias in randomized controlled trials: a case study in dentistry

OBJECTIVE: To evaluate the validity of the Qualis database in identifying the levels of scientific evidence and the quality of randomized controlled trials indexed in the Lilacs database. METHODS: We selected 40 open-access journals and performed a page-by-page hand search, to identify published articles according to the type of study during a period of six years. Classification of studies was performed by independent reviewers assessed for their reliability. Randomized controlled trials were identified for separate evaluation of risk of bias using four dimensions: generation of allocation sequence, allocation concealment, blinding, and incomplete outcome data. The Qualis classification was considered to be the outcome variable. The statistical tests used included Kappa, Spearman's correlation, Kendall-tau and ordinal regressions. RESULTS: Studies with low levels of scientific evidence received similar Qualis classifications when compared to studies with high levels of evidence. In addition, randomized controlled trials with a high risk of bias for the generation of allocation sequences and allocation concealment were more likely to be published in journals with higher Qualis levels. DISCUSSION: The hierarchy level of the scientific evidence as classified by type of research design, as well as by the validity of studies according to the bias control level, was not correlated or associated with Qualis stratification. CONCLUSION: Qualis classifications for journals are not an approximate or indirect predictor of the validity of randomized controlled trials published in these journals and are therefore not a legitimate or appropriate indicator of the validity of randomized controlled trials.

Errores metodológicos en resumenes de trabajos científicos / Metodological errores in scientifical abstracts

El perfil metodológico (PM) de resúmenes (RS) de investigación debería ajustarse a las exigencias del método científico, para asegurar su validez interna. Deben estar explicitados: población en estudio, objetivos, resultados y conclusiones y además, ser conexos y consistentes entre sí. Objetivos, Materiales y Métodos. Determinamos datos descriptivos genéricos y/o PM, de los RS publicados y presentados en Actas de los Congresos Internacionales de Medicina Interna del Hospital de Clínicas de los años 1992 y 1994. Se consideraron: número de RS por congreso, tipo de presentación (oral o escrita), instituciones de origen y número de los autores. Según el n muestral los RS se clasificaron en: Informe Científico (IC) (n=10), Caso único (n < 10), Sin registro (n no informado) y Sin casos (disertaciones). En los IC se analizó el PM: n muestral; tipo de problema; presencia, explicitación y conexidad de objetivos (Ob), resultados (Re) y conclusiones (Co). Se determinaron distribución de frecuencias y/o medidas de tendencia central. Resultados: se analizaron 310 RS: 157 del año 1992 y 153 del año 1994. De 310 trabajos, 81,9 por ciento se presentaron en forma oral y 73,87 por ciento correspondieron a autores de Instituciones Públicas. La media de autores por resumen fue de 5,17 ñ 2,08. Se presentaron: 52,58 por ciento IC; 32,9 por ciento Casos Unicos; 3,55 por ciento Sin Casos y 10,97 por ciento Sin Registro. En los 163 IC la mediana del n fue 67 (rango: 10-82637); 38,03 por ciento presentaban objetivos completos; 50,3 por ciento planteaban problemas de comparación y 44,2 por ciento problemas de cuantificación. Los diseños más frecuentes fueron: observacionales (74,20 por ciento), transversales (72,40 por ciento) y prospectivos (84 por ciento). El 72,4 por ciento informaban Re completos y el 77,9 por ciento Co. Se estableció conexidad en el 33,7 por ciento de los IC entre Re-Co, en el 21,5 por ciento entre Ob-Co, en el 29,40 por ciento entre Ob-Re y sólo en el 11,70 por ciento entre Ob-Re-Co. Conclusiones: 1.- La presentación más corriente fue la de IC, seguida por los Casos Unicos. . .