Background: Individual participant data (IPD) meta-analysis is regarded as the ideal approach for providing evidence on intervention effect estimation because it can derive standardized outcome definitions and use a consistent analysis method. Our previous study has summarized the methodological and reporting quality of published IPDMA (BMJ 2021;372:n736). However, the current practices and perceived best strategies in IPD retrieval are still unclear.
Objectives: The aim of this study is to explore the perceived and practical strategies in IPD retrieval.
Methods: A cross-sectional survey was conducted. Email addresses of IPDMA authors were identified through PubMed. An e-questionnaire with 32 questions, related to the authors’ demographic, their views and practices on different strategies in conducting IPDMA, was created based on literature. Qualitative email interviews were then conducted to gather in-depth information about their barriers and perceived strategies to maximize the IPD retrieval. Descriptive statistics, inferential statistics and linear regression models were used to analyze the data collected from the e-questionnaire while content analysis was undertaken for the qualitative interview. Ethics approval was granted by the university institutional review board.
Results: Of 151 respondents, most were male (62%), aged ≥35 years (80.1%), and academic staff (69.5%) and had >5 years of experience (80.1%). The mean successful rate of retrieving the IPD data was 67.2%. A total of 64.2% included their primary studies in the IPDMA and 44.4% provided authorship for primary study authors as incentive. Email was the most common method to contact study authors (90.1%) and share data (67.5%); it was also ranked the most effective way of requesting IPD. Linear regression models revealed that those (i) aged ≥65 years, (ii) who were academic staff as the first contact person, and (iii) who had a primary study included in the IPDMA had significantly higher success rates. Two main categories were identified from the email interview qualitative responses: (i) ‘Contributors of successful IPD retrieval’ and (ii) ‘Reasons for failed IPD retrievals’. (See Tables)
Conclusions: It was revealed that senior academics working in the field with primary data themselves had a higher chance to retrieve the IPD. Providing authorship of the IPDMA publication to the primary study author may also help to improve the success rate.
Patient, public and/or healthcare consumer involvement: None.

Cochrane abstract 2 - IPDMA.pdf