What makes hospitalized patients more vulnerable and increases their risk of experiencing an adverse event?

OBJECTIVE To analyze the relationship between the appearance of adverse events (AEs) and both patient comorbidities and the use of medical devices. DESIGN Retrospective medical records review study. SETTING Twenty-four Spanish public hospitals. PARTICIPANTS Clinical records of 5624 discharged patients. MAIN OUTCOME MEASURE Incidence of AEs. RESULTS Patients aged >65 have 2.4 times the risk of experiencing an AE compared with those aged <65. The presence of certain comorbidities and devices (neoplasia, chronic hepatic alteration, cardiac insufficiency, coronary disease, high blood pressure, urethral catheterization, catheterization of a vessel, tracheostomy or stay of >7 days) were associated with developing an AE during hospitalization. There is a trend effect if we consider the number of comorbidities and the number of devices used. Thus, the risk of an AE in subjects who present no comorbidities was 3.2%, which rose to 9.9% in those with one intrinsic risk factor, 16.7% in those with two and 29.3% in those with three or more. Similarly, subjects without extrinsic risk factor experienced an AE in 4.4% of cases, which rose to 9.6% when there was one risk factor, to 13.4% when there were two and to 33.0% when there were three or more risk factors. The effect of some of these pathologies and that associated with age disappeared on adjusting in line with other variables. CONCLUSIONS The true risk resides in the number of exposures to potentially iatrogenic actions, rather than being intrinsic to age or the presence of certain comorbidities.