To examine the impact of not blinding outcome assessors on estimates of intervention effects in animal experiments modeling human clinical conditions.We searched PubMed, Biosis, Google Scholar, and HighWire Press and included animal model experiments with both blinded and nonblinded outcome assessors. For each experiment, we calculated the ratio of odds ratios (ROR), that is, the odds ratio (OR) from nonblinded assessments relative to the corresponding OR from blinded assessments. We standardized the ORs according to the experimental hypothesis, such that an ROR <1 indicates that nonblinded assessor exaggerated intervention effect, that is, exaggerated benefit in experiments investigating possible benefit or exaggerated harm in experiments investigating possible harm. We pooled RORs with inverse variance random-effects meta-analysis.We included 10 (2,450 animals) experiments in the main meta-analysis. Outcomes were subjective in most experiments. The pooled ROR was 0.41 (95

作者：Segun, Bello；Lasse T, Krogsb?ll；Jan, Gruber；Zhizhuang J, Zhao；Doris, Fischer；Asbj?rn, Hróbjartsson

来源：Journal of clinical epidemiology 2014 年 67卷 9期