Evaluation of Excess Significance Bias in Animal Studies of Neurological Diseases

Animal studies generate valuable hypotheses that lead to the conduct of preventive or therapeutic clinical trials. We assessed whether there is evidence for excess statistical significance in results of animal studies on neurological disorders, suggesting biases. We used data from meta-analyses of interventions deposited in Collaborative Approach to Meta-Analysis and Review of Animal Data in Experimental Studies (CAMARADES). The number of observed studies with statistically significant results (O) was compared with the expected number (E), based on the statistical power of each study under different assumptions for the plausible effect size. We assessed 4,445 datasets synthesized in 160 meta-analyses on Alzheimer disease (n = 2), experimental autoimmune encephalomyelitis (n = 34), focal ischemia (n = 16), intracerebral hemorrhage (n = 61), Parkinson disease (n = 45), and spinal cord injury (n = 2). 112 meta-analyses (70%) found nominally (p≤0.05) statistically significant summary fixed effects. Assuming the effect size in the most precise study to be a plausible effect, 919 out of 4,445 nominally significant results were expected versus 1,719 observed (p<10-9). Excess significance was present across all neurological disorders, in all subgroups defined by methodological characteristics, and also according to alternative plausible effects. Asymmetry tests also showed evidence of small-study effects in 74 (46%) meta-analyses. Significantly effective interventions with more than 500 animals, and no hints of bias were seen in eight (5%) meta-analyses. Overall, there are too many animal studies with statistically significant results in the literature of neurological disorders. This observation suggests strong biases, with selective analysis and outcome reporting biases being plausible explanations, and provides novel evidence on how these biases might influence the whole research domain of neurological animal literature. © 2013 Tsilidis et al

Renal Carcinoma Metachronous Metastases to the Gall-Bladder and Pancreas - Case Report

Renal carcinoma metastases to the gastrointestinal tract are seldom reported in medical literature. The study presented a case of a 76-year old female patient who underwent nephrectomy, due to T2N0M0 clear cell renal carcinoma and was additionally diagnosed with two metachronous metastases to the gall-bladder and pancreas. Abdominal ultrasound performed 32 months after nephrectomy demonstrated the presence of cholelithiasis and gall-bladder polyp. Laparoscopic cholecystectomy was performed. Clear cell renal carcinoma metastasis restricted to the gall-bladder mucosa was diagnosed on the basis of the histopathological examination. After surgery the patient remained under follow-up. In December, 2009 (47 months after nephrectomy) abdominal computer tomography (CT) revealed the presence of a tumor located in the tail of the pancreas. Distal pancreatic resection and splenectomy was performed. The histopathological examination confirmed the presence of clear cell renal carcinoma metastasis. The patient is in good general condition, under follow-up at the Oncological Outpatient Clinic