Differences in methodological quality between positive and negative published clinical trials.

AIM: Comparison of methodological quality differences in nursing clinical trials with positive and negative findings. BACKGROUND: The growth of nursing publications and increased reliance on data to guide clinical care make publication quality assessment imperative. One major concern is the tendency for more studies with positive findings to be published, potentially resulting in the publication of lower quality trials. DESIGN: Secondary analysis of published trials to compare studies with positive and negative findings in terms of clinical trial quality and sample size calculation methodology. DATA SOURCES: Twenty articles each from three major nursing journals (Journal of Clinical Nursing, Journal of Advanced Nursing and International Journal of Nursing Studies) for the years 2010-2012. We assessed article quality in terms of Jadad scores, methods and total sample size. IMPLICATIONS FOR NURSING: This article underscores the importance of nurses and nursing students having the ability to assess the quality of published trials, so that they can make appropriate judgments on the implementation of care for patients as the use of evidence-based practice increases. CONCLUSION: Potential differences in methodological quality between positive and negative trials may lead to positive trials with biased results, or discrimination against negative trials. The CONSORT is recommended, but use is still limited. Therefore, it is important to reinforce the use of these guidelines to supply readers with information on the quality of the published trials. The combination of authors publishing higher quality trials and deeper reader knowledge of quality assessment can have important clinical consequences.

Biological markers in noninvasive brain stimulation trials in major depressive disorder: a systematic review.

OBJECTIVES: The therapeutic effects of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation in patients with major depression have shown promising results; however, there is a lack of mechanistic studies using biological markers (BMs) as an outcome. Therefore, our aim was to review noninvasive brain stimulation trials in depression using BMs. METHODS: The following databases were used for our systematic review: MEDLINE, Web of Science, Cochrane, and SCIELO. We examined articles published before November 2012 that used TMS and transcranial direct current stimulation as an intervention for depression and had BM as an outcome measure. The search was limited to human studies written in English. RESULTS: Of 1234 potential articles, 52 articles were included. Only studies using TMS were found. Biological markers included immune and endocrine serum markers, neuroimaging techniques, and electrophysiological outcomes. In 12 articles (21.4%), end point BM measurements were not significantly associated with clinical outcomes. All studies reached significant results in the main clinical rating scales. Biological marker outcomes were used as predictors of response, to understand mechanisms of TMS, and as a surrogate of safety. CONCLUSIONS: Functional magnetic resonance imaging, single-photon emission computed tomography, positron emission tomography, magnetic resonance spectroscopy, cortical excitability, and brain-derived neurotrophic factor consistently showed positive results. Brain-derived neurotrophic factor was the best predictor of patients' likeliness to respond. These initial results are promising; however, all studies investigating BMs are small, used heterogeneous samples, and did not take into account confounders such as age, sex, or family history. Based on our findings, we recommend further studies to validate BMs in noninvasive brain stimulation trials in MDD.