Article type
Year
Abstract
Background:
Inadequate and un-standardized reporting of time-to-event (censored) outcomes and statistical analyses in individual randomized controlled trials is well documented. Therefore, meta-analyses of such outcomes frequently require the re-analysis of individual participant data (IPD), an approach which is considered to be ‘gold standard’. However, procedures for obtaining IPD are time-consuming, resource intensive and often unsuccessful due to unavailability of data or concerns regarding collaboration and data sharing. If IPD cannot be obtained for a study, it may have to be excluded from meta-analysis, potentially introducing bias into the results of a review.
Methods:
Since 1997, the Cochrane Epilepsy Group has undertaken an IPD approach for seven pairwise Cochrane reviews and recently for an overview of reviews and network meta-analysis. For all studies identified as eligible for these reviews, an IPD request was made to the lead/corresponding author or the sponsoring organisation if a study was industry funded.
Results:
Within the original seven reviews published between 2000 and 2006, we successfully obtained 78% of IPD for 5363 participants from 30 studies. Following IPD requests for review updates and the overview of reviews from 2011-2014, to date, we have obtained IPD for only 299 participants from four studies out of 7811 eligible from 37 studies (4%). Requests also include nine ongoing industry based requests for data of 4819 participants, some which have been outstanding for over two years. The poor response rate has substantially delayed us from updating our reviews and the proportion of IPD available for inclusion in some reviews has dropped to below 50%. Review specific results and the potential impacts of missing IPD will be presented
Conclusions:
The Cochrane Epilepsy Group has previously had a high success rate in obtaining IPD for Cochrane Reviews however recently our success rate has declined. We are uncertain regarding the reason for this decline, how to improve our success rate and the impact on our current and future IPD reviews.
Inadequate and un-standardized reporting of time-to-event (censored) outcomes and statistical analyses in individual randomized controlled trials is well documented. Therefore, meta-analyses of such outcomes frequently require the re-analysis of individual participant data (IPD), an approach which is considered to be ‘gold standard’. However, procedures for obtaining IPD are time-consuming, resource intensive and often unsuccessful due to unavailability of data or concerns regarding collaboration and data sharing. If IPD cannot be obtained for a study, it may have to be excluded from meta-analysis, potentially introducing bias into the results of a review.
Methods:
Since 1997, the Cochrane Epilepsy Group has undertaken an IPD approach for seven pairwise Cochrane reviews and recently for an overview of reviews and network meta-analysis. For all studies identified as eligible for these reviews, an IPD request was made to the lead/corresponding author or the sponsoring organisation if a study was industry funded.
Results:
Within the original seven reviews published between 2000 and 2006, we successfully obtained 78% of IPD for 5363 participants from 30 studies. Following IPD requests for review updates and the overview of reviews from 2011-2014, to date, we have obtained IPD for only 299 participants from four studies out of 7811 eligible from 37 studies (4%). Requests also include nine ongoing industry based requests for data of 4819 participants, some which have been outstanding for over two years. The poor response rate has substantially delayed us from updating our reviews and the proportion of IPD available for inclusion in some reviews has dropped to below 50%. Review specific results and the potential impacts of missing IPD will be presented
Conclusions:
The Cochrane Epilepsy Group has previously had a high success rate in obtaining IPD for Cochrane Reviews however recently our success rate has declined. We are uncertain regarding the reason for this decline, how to improve our success rate and the impact on our current and future IPD reviews.