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.