In the Eye of the Beholder

Abstract

In the Eye of the Beholder Over the last 25 years the randomized clinical trial and the science of clinical epidemiology have begun to reshape the way medicine is practiced and taught, replacing anecdote and tradition with concrete quantitative data. During the same period, cognitive psycholo-

Reporting of numerical and statistical differences in abstracts

“…The growing body of literature demonstrating that the interpretation of trial results is sensitive to the format in which the data are presented has led to calls for the reporting of absolute rather than just relative measures of therapeutic benefit. 7,10,14,15 Our audit of abstracts published in major medical journals found a marked increase between 1986 and 1996 in the presentation of absolute measures of difference; yet only 12% of the 1996 abstracts we examined presented an ARR or NNT. As with other aspects of quality improvement in published abstracts, progress is slow.…”

“…Despite these efforts to improve the informative content of abstracts, the data presented in them may still lack quantitative measures of statistical significance ( P value and confidence interval [CI]) and may be misinterpreted by readers due to the effect of the outcome format on the appraisal of trial results. 7 Format effects are particularly salient in the setting of a low‐event rate (e.g., 2% death rate), where a large relative risk reduction (RRR) (“50% fewer deaths”) corresponds to only a small absolute risk reduction (ARR)(“1% fewer persons die”) and a large number needed to treat (NNT) (“need to treat 100 people to save 1 life”). A high RRR, when presented alone, will lead more physicians to recommend an intervention, while the reporting of the corresponding low ARR or high NNT will reduce enthusiasm for the intervention.…”