Abstract
Background Mendelian randomisation (MR) is a method of causal inference that uses genetic variation as an instrumental variable (IV) to account for confounding. While the number of MR articles published each year is rapidly rising (partly due to large cohort studies such as the UK Biobank making it easier to conduct MR), it is not currently known whether these studies are appropriately conducted and reported in enough detail for other researchers to accurately replicate and interpret them.
Methods We conducted a systematic review of reporting and analysis quality of MR studies using only individual level data from the UK biobank to calculate a causal estimate. We reviewed 64 eligible articles on a 25-item checklist (based on the STROBE-MR reporting guidelines and the Guidelines for performing Mendelian Randomisation investigations). Information on article type and journal information was also extracted.
Results Overall, the proportion of articles which reported complete information ranged from 2% to 100% across the different items. Palindromic variants, variant replication, missing data, associations between the IV and variables of exposure/outcome and bias introduced by two-sample methods used on a single sample were often not completely addressed (<11%).
There was no clear evidence that Journal Impact Factor, word limit/recommendation or year of publication predicted percentage of article completeness (for the eligible analyses) across items, but there was evidence that whether the MR analyses were primary, joint-primary or secondary analyses did predict completeness.
Conclusions The results identify areas in which the reporting and conducting of MR studies needs to be improved and highlights that this is independent of Journal Impact Factor, year of publication or word limits/recommendations.
Methods We conducted a systematic review of reporting and analysis quality of MR studies using only individual level data from the UK biobank to calculate a causal estimate. We reviewed 64 eligible articles on a 25-item checklist (based on the STROBE-MR reporting guidelines and the Guidelines for performing Mendelian Randomisation investigations). Information on article type and journal information was also extracted.
Results Overall, the proportion of articles which reported complete information ranged from 2% to 100% across the different items. Palindromic variants, variant replication, missing data, associations between the IV and variables of exposure/outcome and bias introduced by two-sample methods used on a single sample were often not completely addressed (<11%).
There was no clear evidence that Journal Impact Factor, word limit/recommendation or year of publication predicted percentage of article completeness (for the eligible analyses) across items, but there was evidence that whether the MR analyses were primary, joint-primary or secondary analyses did predict completeness.
Conclusions The results identify areas in which the reporting and conducting of MR studies needs to be improved and highlights that this is independent of Journal Impact Factor, year of publication or word limits/recommendations.
| Original language | English |
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| Publisher | medRxiv |
| DOIs | |
| Publication status | Published - 26 Apr 2022 |
Funding
MJG, AC and MRM are supported by the Medical Research Council Integrative Epidemiology Unit (MC_UU_00011/7). FS, JNK and RCR are supported by a Cancer Research UK programme grant (the Integrative Cancer Epidemiology Programme C18281/A29019). RCR is a de Pass Vice Chancellors Research Fellow at the University of Bristol. The funders had no role in the study design, collection or analysis of data, or interpretation of results. The views expressed in this article are those of the authors and not necessarily any funder or acknowledged person/institution.