Figure 1.

Conceptual diagram of the self-controlled case series analysis. (A) Hypothetical timeline for a patient with three exposures and one severe sepsis hospitalization. (B) Hypothetical shifts in microbiome health associated with the patient’s clinical history. Microbial diversity is in constant flux, with periods of disruption (dysbiosis) corresponding with hospitalization. (C) Classification of baseline and higher risk periods used to calculate the incidence risk ratios for severe sepsis following each of the three exposures. The baseline risk of sepsis increases over time as patients age, which is accounted for in the model. CDI = Clostridium difficile infection.