Fig. 2
![Fig. 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12916-015-0381-9/MediaObjects/12916_2015_381_Fig2_HTML.gif)
Flow chart of unexposed control patients included in the study. Crd1: current registration date in practice. Uts2: practice data up to standard quality
Flow chart of unexposed control patients included in the study. Crd1: current registration date in practice. Uts2: practice data up to standard quality