Centre for Research in Evidence-Based Practice, Faculty of Health Sciences and Medicine, Bond University, 4229 Qld, Australia.
BMJ. 2012 May 17;344:e3223. doi: 10.1136/bmj.e3223.
To estimate the degree of scatter of reports of randomised trials and systematic reviews, and how the scatter differs among medical specialties and subspecialties.
Cross sectional analysis.
PubMed for all disease relevant randomised trials and systematic reviews published in 2009.
Randomised trials and systematic reviews of the nine diseases or disorders with the highest burden of disease, and the broader category of disease to which each belonged.
The scatter across journals varied considerably among specialties and subspecialties: otolaryngology had the least scatter (363 trials across 167 journals) and neurology the most (2770 trials across 896 journals). In only three subspecialties (lung cancer, chronic obstructive pulmonary disease, hearing loss) were 10 or fewer journals needed to locate 50% of trials. The scatter was less for systematic reviews: hearing loss had the least scatter (10 reviews across nine journals) and cancer the most (670 reviews across 279 journals). For some specialties and subspecialties the papers were concentrated in specialty journals; whereas for others, few of the top 10 journals were a specialty journal for that area. Generally, little overlap occurred between the top 10 journals publishing trials and those publishing systematic reviews. The number of journals required to find all trials or reviews was highly correlated (r = 0.97) with the number of papers for each specialty/subspecialty.
Publication rates of speciality relevant trials vary widely, from one to seven trials per day, and are scattered across hundreds of general and specialty journals. Although systematic reviews reduce the extent of scatter, they are still widely scattered and mostly in different journals to those of randomised trials. Personal subscriptions to journals, which are insufficient for keeping up to date with knowledge, need to be supplemented by other methods such as journal scanning services or systems that cover sufficient journals and filter articles for quality and relevance. Few current systems seem adequate.
评估随机试验和系统评价报告的分散程度，以及这种分散在不同医学专业和亚专业之间的差异。
横断面分析。
PubMed 收录的 2009 年所有与疾病相关的随机试验和系统评价。
对九种疾病或疾病负担最高的疾病类别以及每种疾病所属的更广泛类别进行随机试验和系统评价。
期刊间的分散程度在专业和亚专业之间差异很大：耳鼻喉科的分散程度最小（167 种期刊中有 363 项试验），神经病学的分散程度最大（896 种期刊中有 2770 项试验）。只有三个亚专业（肺癌、慢性阻塞性肺疾病、听力损失）需要 10 种或更少的期刊来定位 50%的试验。系统评价的分散程度较小：听力损失的分散程度最小（9 种期刊中有 10 项评价），癌症的分散程度最大（279 种期刊中有 670 项评价）。对于一些专业和亚专业，论文集中在专业期刊上；而对于其他专业，排名前 10 的期刊中很少有专门针对该领域的期刊。一般来说，发表试验的排名前 10 的期刊与发表系统评价的期刊之间很少有重叠。找到所有试验或综述所需的期刊数量与每个专业/亚专业的论文数量高度相关（r = 0.97）。
专业相关试验的发表率差异很大，每天从一篇到七篇不等，分散在数百种普通和专业期刊中。尽管系统评价减少了分散程度，但它们仍然广泛分散，并且大多数与随机试验的期刊不同。个人订阅期刊不足以跟上知识的更新，需要通过其他方法来补充，例如期刊扫描服务或涵盖足够期刊并筛选文章质量和相关性的系统。目前似乎很少有系统是足够的。
