Fig. 2

Prevalence of co-administration and interaction by age during the first 18 months of the studies. Green, red, and blue lines denote measurements for Blumenau, Catalonia, and Indianapolis, respectively. a Prevalence of co-administration of drugs. b Prevalence of co-administration of drugs known to interact. c–e Prevalence of interactions against the respective null model in c Blumenau, d Catalonia, and e Indianapolis. Circles denote the values obtained with the real data, while the asterisks denote the values obtained using the null model. The associated relative risk is shown above the points. Asterisks denote significant differences (Fisher’s exact test)