Methodological quality of preclinical stroke studies is not required for publication in high-impact journals

Abstract

Omitting quality characteristics in animal stroke studies leads to an overestimation of the efficacy of candidate stroke drugs. Nevertheless, the methodological quality of preclinical stroke studies is often limited. As publishing of research results in high-impact journals is an important motivation for scientists, we analyzed whether study quality predicts high-impact publishing. Animal stroke studies of neuroprotective drugs that were recently investigated in clinical phase II/III trials were included in the analysis. Data on the study quality and other important study characteristics were extracted. Regression analyses were performed to estimate the effect of the study characteristics on the journal's impact factor. We identified 117 studies that investigated 12 different drugs. Study quality was not associated with the impact factor before (beta=-0.2, P=0.50) and after adjustment for other study characteristics (beta=-0.3, P=0.19). There was a significant association of the number of investigated mechanisms and applied techniques with the impact factor (beta=1.4, P<0.0001). Our findings show that the quality of animal experimental stroke studies is not relevant for publishing in high-impact journals. The major predictor for accepting preclinical stroke studies in high-impact journals is the complexity of the investigation into a stroke drug's mode of action.

Figure 1

Flow chart for selection of studies. Overall, 102 studies were identified searching the database http://www.Clinicaltrials.gov. The terms ‘acute stroke' (conditions), ‘Phase II,' or ‘Phase III' (phase) were used. In all, 44 studies were excluded as nonneuroprotective drugs, such as thrombolytic agents were used. Another 22 studies were excluded for the use of devices and other nonpharmaceutical therapies (such as electrical simulation and gait trainer). In 10 studies, more than one drug was investigated in stroke. Six studies investigated therapies in conditions other than stroke. Of three drugs, the results of animal experimental stroke studies were not published in peer-reviewed journals. Overall, 12 candidate stroke drugs were investigated in 117 animal studies of focal cerebral ischemia.

Figure 2

Association between quality score and impact factor. The middle line is the median, and the outer bounds are the 25th and the 75th percentiles. There was no association between the quality score and the impact factor before (β=−0.2, P=0.50) and after adjustment (β=−0.3, P=0.19) for other study characteristics.