Harm caused by adverse events in primary care: a clinical observational study.
Wetzels R, Wolters R, van Weel C, et al. Harm caused by adverse events in primary care: a clinical observational study. J Eval Clin Pract. 2009;15(2):323-7. doi:10.1111/j.1365-2753.2008.01005.x.
This study analyzed adverse events in two primary care practices and found that half had health consequences and a third led to worsening of symptoms or an unplanned hospital admission.