E. coli 0157:H7 and hypertension, renal and cardiac disease
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Overall, people who had acute gastroenteritis were 1.3 times more likely to develop hypertension, 3.4 times more likely to develop both structural and functional renal impairment, and 2.1 times more likely to report a physician-diagnosed cardiac disease. The authors do an excellent job discussing the potential limitations of the study including recall bias and confounding. They also explain away the impact of Campylobacter coinfection by saying that the infectious dose of 0157:H7 is 10 bacteria, while it is 500 for Campylobacter, so people were unlikely to have avoided 0157:H7 exposure.
This is a very unique study. Most studies that have assessed infections as risk factors for chronic diseases were case-control studies that identified patients with specific outcomes and looked back for certain risk factors. You would imagine that recall bias would play a much larger role in remembering certain distant and unremarkable exposures like GI illness in a case-control study. With this cohort study, exposures and outcomes were well characterized and measured. I wonder what this study's impact will be in ascertaining the causes of hypertension, renal and cardiac disease in the general population? Their recommendation that patients who are post-exposure from E coli 0157:H7 should be carefully monitored for hypertension and renal disease seems prudent.
Clark WF et al. BMJ Nov. 17, 2010 (open access)