Handsearching versus electronic searching to identify reports of randomized trials

  • Review
  • Methodology

Authors


Abstract

Background

Systematic reviewers need to decide how best to reduce bias in identifying studies for their review. Even when journals are indexed in electronic databases, it can still be difficult to identify all relevant studies reported in these journals. Over 1700 journals have been or are being handsearched within The Cochrane Collaboration to identify reports of controlled trials in order to help address these problems.

Objectives

To review systematically empirical studies, which have compared the results of handsearching with the results of searching one or more electronic databases to identify reports of randomized trials.

Search methods

Studies were sought from The Cochrane Methodology Register (The Cochrane Library, Issue 2, 2002), MEDLINE (1966 to Week 1 July 2002), EMBASE (1980 to Week 25 2002), AMED (1985 to June 2002), BIOSIS (1985 to June 2002), CINAHL (1982 to June 2002), LISA (1969 to July 2002) and PsycINFO (1972 to May 2002). Researchers who may have carried out relevant studies were contacted.

Selection criteria

A research study was considered eligible for this review if it compared handsearching with searching one or more electronic databases to identify reports of randomized trials.

Data collection and analysis

The main outcome measure was the number of reports of randomized trials identified by handsearching as compared to electronic searching. Data were extracted on the electronic database searched, the complexity of electronic search strategy used, the characteristics of the journal reports identified, and the type of trial report identified.

Main results

Thirty-four studies were included. Handsearching identified between 92% to 100% of the total number of reports of randomized trials found in the various comparisons in this review. Searching MEDLINE retrieved 55%, EMBASE 49% and PyscINFO 67%. The retrieval rate of the electronic database varied depending on the complexity of the search. The Cochrane Highly Sensitive Search Strategy (HSSS) identified 80% of the total number of reports of randomized trials found, searches categorised as 'complex' (including the Cochrane HSSS) found 65% and 'simple' found 42%. The retrieval rate for an electronic search was higher when the search was restricted to English language journals; 62% versus 39% for journals published in languages other than English. When the search was restricted to full reports of randomized trials, the retrieval rate for an electronic search improved: a complex search strategy (including the Cochrane HSSS) retrieved 82% of the total number of such reports of randomized trials.

Authors' conclusions

Handsearching still has a valuable role to play in identifying reports of randomized trials for inclusion in systematic reviews of health care interventions, particularly in identifying trials reported as abstracts, letters and those published in languages other than English, together with all reports published in journals not indexed in electronic databases. However, where time and resources are limited, searching an electronic database using a complex search (or the Cochrane HSSS) will identify the majority of trials published as full reports in English language journals, provided, of course, that the relevant journals have been indexed in the database.

摘要

背景

人工和電腦搜尋隨機臨床試驗(randomized trials)報告之比較

系統性回顧者需要擬定搜尋相關研究文獻的方式﹐並減少過程中的偏差。即使電子資料庫已建立期刊的索引資料,要找出期刊中所有相關研究仍有困難。為了解決此一問題,Cochrane Collaboration以人工方式搜尋1700種以上期刊中的對照臨床試驗(controlled trials)報告。

目標

進行人工搜尋和電子搜尋多個資料庫中的隨機臨床試驗﹐並個別進行實證研究的系統性地回顧﹐比較二者結果差異。

搜尋策略

我們自Cochrane Methodology Register (The Cochrane Library, Issue 2, 2002), MEDLINE (1966年至2002年7月第一周), EMBASE (1980 年至2002年第25週), AMED (1985年至2002年6月), BIOSIS (1985年至2002年6月), CINAHL (1982年至2002年6月)﹐LISA (1969年至2002年7月) 以及PsycINFO (1972年至2002年5月)﹐尋找相關研究,並聯繫可能進行過相關研究的人員。

選擇標準

凡同為凡是比較人工搜尋隨機臨床試驗報告和電子搜尋利用一個以上多個電子資料庫尋找隨機臨床試驗報告搜尋同樣資料的實證研究,均納入是本回顧探討的對象。

資料收集與分析

比較結果的依據指標主要是人工搜尋和電子搜尋找到的隨機臨床試驗報告的數目。另外收集的資料包括了所搜尋的電子資料庫,搜尋策略的複雜度,搜尋到的文獻報告特徵﹐以及這些臨床試驗報告的種類等。

主要結論

總共包含34個研究。在本回顧探討的各種不同比較當中﹐人工搜尋找到的隨機臨床試驗報告佔所有報告總數比例從92%到100%不等。從MEDLINE可找到報告總數的55%,EMBASE 可找到49% ﹐PyscINFO有 67%。電子資料庫的尋獲率(retrieval rate)依搜尋策略的複雜度而定。Cochrane Highly Sensitive Search Strategy (HSSS)可尋獲80%。使用進階搜尋策略(包含HSSS)可尋獲65%,一般搜尋可尋獲42%。如搜尋範圍限定英文期刊﹐電子資料庫尋獲率為62%﹐搜尋不是以英文出版的期刊尋獲率為39%。當搜尋範圍限定完整報告時,可提高電子資料庫尋獲率,以進階搜尋(包含HSSS)可尋獲82%。

作者結論

當系統性回顧醫療處置類的研究文獻時,特別是當隨機臨床試驗是以摘要、投書、非英語等的形式發表﹐或發表在電子資料庫未收錄的雜誌時﹐以人工搜尋隨機臨床試驗報告仍具相當的價值。然而時間及資源有限之下,只要是電子資料庫有收錄的雜誌,以進階搜尋(或Cochrane HSSS)應能搜尋到在英文學術期刊完整發表之研究的絕大部份。

翻譯人

本摘要由慈濟醫院葉日弌翻譯。

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

無總結

Plain language summary

Handsearching versus electronic searching to identify reports of randomized trials

This review shows that handsearching alone will miss a small proportion of studies and, that a combination of handsearching and electronic searching is the most comprehensive approach in identifying reports of randomized trials.