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Re-analysis challenges key helmet research

A peer-reviewed paper accepted for publication in Accident Analysis & Prevention finds that a previous meta-analysis of bicycle helmet efficacy reported by Attewell, Glase, and McFadden (Accident Analysis and Prevention 2001, 345352) was influenced by publication bias and time-trend bias that was not controlled for. As a result, the analysis reported inflated estimates of the effects of bicycle helmets.

The new paper, by Elvik Rune of the Norwegian Institute of Transport Economics, presents a re-analysis of the study. The re-analysis included: (1) detecting and adjusting for publication bias by means of the trim-and-fill method; (2) ensuring the inclusion of all published studies by means of continuity corrections of estimates of effect rely on zero counts; (3) detecting and trying to account for a time-trend bias in estimates of the effects of bicycle helmets; (4) updating the study by including recently published studies evaluating the effects of bicycle helmets.

The re-analysis finds that when these sources of bias are controlled for, and new studies added to the analysis, the effects attributed to bicycle helmets become considerably smaller than originally reported. Moreover, the findings of this meta-analysis are not consistent with a subsequent Cochrane review.

Sat 12 Feb 2011

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