Objective: To determine the incidence of patients with adverse events (AE) in Spanish general surgery units, describe the immediate causes of AE, identify avoidable AE, and determine the impact of these events.
Material and method: We performed a retrospective cohort study of a randomized stratified sample of 24 hospitals. Six of the hospitals were small (fewer than 200 beds), 13 were medium-sized (between 200 and 499 beds) and five were large (500 or more beds). Patients admitted for more than 24 hours to the selected hospitals and who were discharged between the 4th and 10th of June 2005 were included. AE detected during hospitalization and those occurring as a consequence of previous admissions in the same hospital were analyzed.
Results: The incidence of patients with AE associated with medical care was 10.5% (76/735; 95%CI: 8.1%-12.5%). The presence of intrinsic risk factors increased the risk of AE (14.8% vs 7.2%; P=.001). Likewise, 16.2% of patients with an extrinsic risk factor had an AE compared with 7.0% of those without these risk factors (P< .001). Comorbidity influenced the occurrence of AE (33.7% of AE vs. 2.2% without comorbidity; P< .001). The severity of the AE was related to ASA risk (P=.036). AE were related to nosocomial infection (41.7%), procedures (27.1%) and medication (24%). A total of 31.3% of the AE were mild, 39.6% were moderate, and 29.2% were severe. Preventable AE accounted for 36.5%. AE caused an additional 527 days of stay (6.3 additional days of stay per patient), of which 216 were due to preventable AE.
Conclusions: Patients in general and digestive surgery units have an increased risk of AE. Risk factors for these events are age, comorbidity, and the use of external devices. A substantial number of AE are related to nosocomial infection (especially surgical wound infection) and to surgical procedures. AE have an important impact on patients and a considerable proportion of these events are preventable. AE have strong health, social and economic repercussions and until recently have constituted a silent epidemic in Spain. Consequently, study of these events should be a public health priority.