There estimate per standard deviation (SD) increase in CRP on pneumonia susceptibility was significantly non-zero and positive in all of the models except for the MR-Egger approach (Fig. 4a, Supplementary Data 15); for example, in the IVW-MRE construct OR per SD CRP = 1.08 [95% CI: 1.02, 1.14], P = 6.47 × 10−3, whilst the IVW-FE produced a more precise positive estimate (P = 5.47 × 10−5), in line with how multiplicative random effects more explicitly models heterogeneity between IVs. Here, CRP is linked to susceptibility to pneumonia measurement.