Abstracts of presentations at scientific meetings are usually available only in conference proceedings. If subsequent full publication of abstract results is based on the magnitude or direction of study results, publication bias may result. Publication bias, in turn, creates problems for those conducting systematic reviews or relying on the published literature for evidence.
To determine the rate at which abstract results are subsequently published in full, and the time between meeting presentation and full publication.
We searched MEDLINE, EMBASE, The Cochrane Library, Science Citation Index, reference lists, and author files. Date of most recent search: June 2003.
We included all reports that examined the subsequent full publication rate of biomedical results initially presented as abstracts or in summary form. Follow-up of abstracts had to be at least two years.
Two reviewers extracted data. We calculated the weighted mean full publication rate and time to full publication. Dichotomous variables were analyzed using relative risk and random effects models. We assessed time to publication using Kaplan-Meier survival analyses.
Combining data from 79 reports (29,729 abstracts) resulted in a weighted mean full publication rate of 44.5% (95% confidence interval (CI) 43.9 to 45.1). Survival analyses resulted in an estimated publication rate at 9 years of 52.6% for all studies, 63.1% for randomized or controlled clinical trials, and 49.3% for other types of study designs.
'Positive' results defined as any 'significant' result showed an association with full publication (RR = 1.30; CI 1.14 to 1.47), as did 'positive' results defined as a result favoring the experimental treatment (RR =1.17; CI 1.02 to 1.35), and 'positive' results emanating from randomized or controlled clinical trials (RR = 1.18, CI 1.07 to 1.30).
Other factors associated with full publication include oral presentation (RR = 1.28; CI 1.09 to 1.49); acceptance for meeting presentation (RR = 1.78; CI 1.50 to 2.12); randomized trial study design (RR = 1.24; CI 1.14 to 1.36); and basic research (RR = 0.79; CI 0.70 to 0.89). Higher quality of abstracts describing randomized or controlled clinical trials was also associated with full publication (RR = 1.30, CI 1.00 to 1.71).
Only 63% of results from abstracts describing randomized or controlled clinical trials are published in full. 'Positive' results were more frequently published than not 'positive' results.
研究成果以摘要形式先行發表﹐其後續之完整發表
在科學會議中展示的摘要通常只在會議專刊中才能找到。如果因為研究結果顯著與否或因為最後結果﹐而影響到後續是否將摘要完整發表﹐就會造成發表偏差(Publication bias)。對於做系統性回顧者﹐及以發表的文獻作實證搜尋者﹐出版偏差會造成問題。
調查摘要發表後﹐後續再發表完整論文的比例﹐及從發表摘要到發表完整論文的時間間隔。
我們搜尋MEDLINE, EMBASE, Cochrane Library, Science Citation Index,參考文獻清單及作者檔案。最後一次搜尋的日期為2003年6月
凡是探討以摘要或總結形式發表的生物醫學研究成果﹐最終以完整報告形式發表的比例之研究，均納入分析。對摘要的追蹤至少兩年以上。
兩位作者擷取資料﹐計算完整報告發表率及摘要發表至完整論文發表間隔時間的加權平均。二元變項(Dichotomous variables)以相對風險(relative risk) 及隨機效應模型(random effects models)分析。摘要發表至完整論文發表時間以KaplanMeier 存活分析(KaplanMeier survival analyses)評定。
結合79篇報告資料(共29,729 篇摘要) ﹐算出完整發表率加權平均為44.5% (95% confidence interval (CI)43.9 – 45.1)。以存活分析估計9年後完整發表率﹔所有研究的發表率估計為52.6%﹐隨機或對照臨床試驗為63.1%，其他類型研究則為49.3%。正面結果如定義是任何達到統計上顯著意義的結果，確實和後續完整發表有正相關(RR = 1.30; CI 1.14 – 1.47)﹔正面結果如定義為實驗組的治療有效，也同樣與後續完整發表有正相關(RR = 1.17; CI 1.02 – 1.35)，隨機或對照臨床試驗如呈現正面結果亦然(RR = 1.18, CI 1.07 – 1.30)。其它和完整發表有關的因素包括口頭發表(RR = 1.28; CI 1.09 – 1.49)、被接受在會議中發表(RR = 1.78; CI 1.50 – 2.12)、隨機臨床試驗(RR = 1.24; CI 1.14 – 1.36)，及基礎型研究(RR = 0.79; CI 0.70 – 0.89)。屬於高品質的隨機或對照臨床試驗的摘要其研究成果比較會作後續完整發表(RR = 1.30, CI 1.00 – 1.71)。
敘述隨機或對照試驗的摘要﹐只有63%的比例將來會以完整的論文發表。結果正面者比無正面結果者被發表的機會較高。
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。
最初以會議摘要形式發表的研究如果有正面的結果，比起研究成果為負面者﹐後續以完整報告形式發表的機會較高。一開始在專業會議以總結或摘要報告的研究，只有不到一半將完整發表在有同儕審查的雜誌上﹔如果只考慮隨機或對照臨床試驗﹐則約有60％。決定摘要將來是否完整發表﹐一個很重要的因素是摘要的正面結果。因此﹐想要收集某主題完整資料﹐可能因此無法如願﹐第一可能原因﹐研究人員沒有把摘要作後續完整發表﹔第二﹐具統計上顯著意義的研究成果比較會作後續完整發表。這種種因素導致系統性回顧會高估治療效果。
Studies initially reported as conference abstracts that have positive results are subsequently published as full-length journal articles more often than studies with negative results.
Less than half of all studies, and about 60% of randomized or controlled clinical trials, initially presented as summaries or abstracts at professional meetings are subsequently published as peer-reviewed journal articles. An important factor appearing to influence whether a study described in an abstract is published in full is the presence of 'positive' results in the abstract. Thus, the efforts of persons trying to collect all of the evidence in a field may be stymied, first by the failure of investigators to take abstract study results to full publication, and second, by the tendency to take to full publication only those studies reporting 'significant' results. The consequence of this is that systematic reviews will tend to over-estimate treatment effects.