Figure 2.

Random-effects model examining the association between common infections and risk of childhood acute lymphoblastic leukaemia. CI represents confidence interval. Common infections are reported as a two-class variable, or highest vs lowest in more than two categories. The secondary analysis for frequency of infections is a combined maximum likelihood effect estimate that estimates a trend from summarised dose–response data. The presence of parvovirus B19 was measured as a dichotomous variable, presence of IgG antibodies vs no IgG antibodies for parvovirus B19. All other studies, the reference was no infections.