There was considerable variation in trial design, such as patient characteristics, the type and application of interventions, the overall care programmes and so on.
Another QTL for leaf rolling under drought in the MSE was detected near RM101 on chromosome 12, explaining 27.3%% of the phenotypic variation in trial 1.
Reports examining the utility of IVIG or CMV IgG in HSCT are hampered by marked variation in trial design and dosing and diverse patient characteristics.
Similarly, a QTL for days to 50%% flowering under drought was identified near RM314 on chromosome 6, explaining 55.8 % of the phenotypic variation in trial 2, with the positive allele coming from the landrace, Nootripathu.
Including qualitative evidence on patients' perspectives in systematic reviews of complex interventions may reveal reasons for variation in trial findings.
This may be explained by the variation in trial populations and limit the generalisability of the results of specific populations [ 6].
A global research observatory would provide a transparent and long term mechanism for setting research priorities, a necessary step to improve research equity in global health and potentially reduce the extreme variation in trial evidence observed in this analysis.
To mimic the variation in trial sizes, we explicitly varied the sample sizes of the trials within the simulated meta-analyses, varying from scenarios where all trials in a meta-analysis were of equal size, to scenarios with only one large trial, 10 times as large as the other trials, or one small trial, 10 times smaller than the other trials.
However, in view of the different populations studied at different locations in the BLISS trials and the consistently superior results from one trial compared with the other, we consider that population heterogeneity, geographical differences and variation in trial conduct and outcome assessment may have played a role in influencing the outcomes.
Statistical analysis of the matrix data may be restricted because of the limited data points that mixed review evidence could provide but further analysis could explore, in a review with more methodologically robust trials, the value of using the algorithmic logic of QCA to explore variation in trial findings.
