Central line-associated bloodstream infections and catheter dwell-time: A theoretical foundation for a rule of thumb

•Central line-associated bloodstream infections (CLABSI) pose a major health concern, and account for a significant increase in morbidity and mortality among hospitalized patients.•The pattern of increase in CLABSI risk with an increase in catheter dwell-time remains obscure, and lacks any theoretical basis.•A better insight into the pattern of CLABSI occurrence over time would provide a rational basis for clinicians to make risk assessments.•Here, a clinically convenient rule of thumb is derived, which broadly states that the CLABSI risk increases in a quadratic fashion with the increase in catheter dwell-time. Many clinicians know from experience and medical epidemiological literature that the risk of central line-associated bloodstream infections (CLABSI) increases rapidly with a prolonged catheter dwell-time, but how this infection risk increases over time remains obscure. In this manuscript, a clinically useful rule of thumb is derived, stating that the risk of CLABSI increases in a quadratic fashion with the increase in catheter dwell-time. The proposed rule of thumb could be considered a quick and effortless clinical tool to rationally predict the pattern of CLABSI risk with an increasing catheter dwell-time