The use of 'trend' statements in veterinary oncology literature.

Statements such as 'trend towards' and 'tended to' in regards to 'statistical significance' are ambiguous and reflect the continued focus on proximity of p-values to .05. By themselves, p-values do not provide a measure of effect size or other information needed to judge clinical importance. The goal of this study was to examine original research articles in the journal Veterinary and Comparative Oncology over 2 years, and describe the use of 'trend' statements. Articles were reviewed for 'trend' and 'tended to' statements, the number of statements made per paper, whether a p-value and/or 95% confidence interval was provided to accompany these statements, and what the p-value was (if provided). We noted 15.8% of articles included at least one 'trend' or 'tended to' statement to describe differences between groups. Specifically, 10.5% of articles used these statements to describe differences without providing the associated p-value, or where p > .05. Of the total 36 'trend' statements noted, six were not accompanied by p-values and eight were associated with p-values >.10. Similarly, four of the 16 'tended to' statements were not accompanied by p-values, and one was associated with a p-value >.10. These data reveal a similar emphasis on p-value proximity in veterinary oncology literature compared to that of human oncology literature. Furthermore, these findings highlight the ambiguity of 'trend' statements and support the development of additional guidelines (e.g., the de-emphasis of p-value proximity to an arbitrary threshold, and effect size reporting) for interpreting results in veterinary oncology research.