Ross-White Amanda, Godfrey Christina
Bracken Health Sciences Library, Queen's University, Kingston, Ontario, Canada.
Queen's Joanna Briggs Collaboration, School of Nursing, Queen's University, Kingston, Ontario, Canada.
Health Info Libr J. 2017 Sep;34(3):217-224. doi: 10.1111/hir.12185. Epub 2017 Jun 27.
To determine whether calculation of a 'Number Needed to Retrieve' (NNTR) is possible and desirable as a means of evaluating the utility of a database for systematic review.
To determine an overall NNTR, eight systematic reviews were tracked to determine how many abstracts were retrieved compared to the number of articles meeting the inclusion criteria. An NNTR was calculated for each database searched to measure the utility of including it in systematic review searches.
Across eight systematic reviews, 17 378 abstracts were reviewed. Of these, 122 met the inclusion criteria for their reviews resulting in an overall NNTR of 142. Individual reviews had an NNTR range of 28-310. Three databases delivered unique results (medline, cinahl and globalhealth). The majority of the included studies appeared in multiple databases. Only five articles were found in a single database.
This research offers a proof of concept of 'NNTR'. While the eight review NNTRs varied widely, all were consistent with the range initially reported by Booth. Included articles consistently appeared in multiple databases, suggesting that duplicate abstracts should be screened first as these are likely to include highly relevant, high-quality results.
确定计算“检索所需数量”（NNTR）作为评估数据库用于系统评价的效用的一种方法是否可行且可取。
为确定总体NNTR，追踪了八项系统评价，以确定与符合纳入标准的文章数量相比检索到的摘要数量。为每个检索的数据库计算NNTR，以衡量将其纳入系统评价检索的效用。
在八项系统评价中，共审查了17378篇摘要。其中，122篇符合其评价的纳入标准，总体NNTR为142。个别评价的NNTR范围为28至310。三个数据库提供了独特的结果（医学索引数据库、护理学与健康领域数据库和全球健康数据库）。大多数纳入研究出现在多个数据库中。仅在一个数据库中发现了五篇文章。
本研究提供了“NNTR”的概念验证。虽然八项评价的NNTR差异很大，但均与布斯最初报告的范围一致。纳入的文章始终出现在多个数据库中，这表明应首先筛选重复的摘要，因为这些摘要可能包含高度相关的高质量结果。
