**4. Methodological Quality**

Overall, the risk of bias of the included studies was high. Often, the nature of the intervention precluded adequate blinding of the operators involved in the blood taking procedures. Whilst it was discussed by the review team that this would be inherent in the included studies, it would still warrant a rating of a "high" for this particular domain. Table 3 details the risk of bias assessments for each domain for included studies, whilst Figure 2 displays the percentage of studies that achieved either a low, unclear or high risk of bias for each domain. See Supplementary Table S2 for full reviewer judgment for the assessment of methodological quality.

**Figure 2.** Percentage of studies that achieved either a low, unclear or high risk of bias for each domain using the SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE) risk of bias tool. Although randomisation was mentioned in several articles, lack of reporting of the method used resulted in an unclear risk of bias for most items. Blinding was impossible to achieve due to the inherent nature of the study design.

