Over the past few years, there has been a growing interest on the part of international and government agencies, as well as local healthcare organizations, in improving inpatient and outpatient safety.^1,2 The goal is to prevent adverse events defined as unintentional harm to the patient during care or as a result of it, ³ as well as to mitigate their impact on the patient. ^1,2 Adverse events have also been called reportable events (REs). ⁴ This latter designation is embraced by the authors of this study in an attempt at reducing the punitive and stigmatizing connotations associated with the term "adverse", and also with the aim of encouraging reporting so that analysis of the events may be conducted under a modified perspective of RE with unwanted effects (REUE).

The frequency of REUE ranges between 2.8% and 32.2%, depending on the service where they are measured, ⁵ the type of institution, ⁶ the specialty (more frequent in surgical services), ⁵ and the measurement methodology. ^7,8 Of this percentage, 30% to 70% are preventable and 4% to 21% contribute to patient death.^3,5-6,9-14 It has been described that REs are more frequent in individuals over 45 years of age (odds ratio 1.5; 95% confidence intervals [CI] 1.4-1.7), ¹⁵ during non-elective surgical procedures, ¹⁶ in patients with comorbidities, ¹⁷ and in high-complexity institutions. However, there is controversy regarding whether the frequency of REUEs is higher in teaching hospitals as compared to other institutions, ⁶ based on the argument that these hospitals receive patients with more complex conditions or greater systemic compromise. Likewise, the issue of age as an independent risk factor is also controversial. ^15,17

International institutional performance indicators include effective patient safety goals¹⁸ which measure the frequency of REs associated with healthcare provision in the hospital, including transfusions, medication administration, and healthcare-associated infections. Hence, the importance of continuously measuring the frequency of REUEs, particularly preventable ones, in order to comply with the international performance goals.

On the other hand, recognizing factors that contribute to REUEs does not only contribute to the understanding of the context and circumstances in which they occur but also helps develop improvement plans for their prevention, which is a patient safety goal. In accordance with this background, the objective of this study was to estimate the incidence and preventability of REUEs and to identify contributing factors in the surgical services of a university hospital in the city of Bogotá D.C., Colombia.

A total of 1246 patients were admitted to the surgery services between May 1 and July 30, 2017; of them, 236 were randomized, 33 did not meet the inclusion criteria, and 1 declined to participate in the study, for a final sample of 202 patients. Of the participants, 52.47% (n = 106) were women, the mean age was 51.93 years (range: 18-93 years), 43.5% (n = 88) of the participants were older than 60 years of age. On the other hand, 80.7% (n = 163) of the participants were referred from a different institution, 60% had at least 1 comorbidity measured with the Charlson index, and 25.74% had 3 or more comorbidities.

A surgical procedure was performed in 67.49% (n = 137) and the remaining percentage of patients, despite having a condition requiring surgery, did not need a surgical procedure during hospitalization. Regarding scheduling of surgical procedures, 54.74% of the subjects (n = 75) required emergency procedures while the remaining 45.25% were taken to elective surgery (Table 2). The specialty associated with the largest number of procedures was general surgery with 31.2% (n=63), followed by urology 8.91% (n = 18), gastroenterology 6.4% (n = 13), orthopaedics 5.94% (n = 12), and neurosurgery 2.47% (n = 5). The remaining entries were spread among other services, including plastic, vascular, chest, head and neck, and maxillofacial surgery; 32.1% were patients seen by more than 1 surgical specialty.

Table 2

* Median and ranges.

A total of 57 subjects (28.21%) had detection events (104); of the total number of subjects, 28 (49.13%) had 2 or more detection events. Of the detection events, 60 were identified during hospitalization in 37 subjects (18.31%), and 44 in 27 subjects (13.36%) during follow-up.

The Harvard Medical Practice Study is one of the first documents published in the scientific literature that reported an incidence of REUE of 3.7%. This result prompted further publications of relevant studies and methods for REUE detection, which have shown an increase in the incidence values over those initially published.21

This study found an incidence of REUEs of 11.88%, similar to the one reported in other countries such as Spain in 2006 (8.4%),22 New Zealand (12.9%),12 London (10.8%), and specifically in a surgery service in London (16.2%).5 It is important to highlight that, compared to studies published recently in the United States and Norway (32%),13,14 incidence is lower.

This variability in incidence values is due to the changeability in the definitions and methods used for REUE classification and analysis. The characteristics of the institutions and of the patients receiving care in those institutions are among other factors that may explain this wide range of values.

This study revealed particular characteristics of the sample considered as risk factors for REUE. These include age over 40 years (77.6%), comorbidities measured with the Charlson index in up to 60% (3 or more comorbidities in 25.74%), and other findings such as increased degree of care complexity.

The participants included in this study were only surgical patients, which in itself is a factor associated with high incidence values considering that, according to the reports in the literature, surgery services account for 51% to 77% of all REs in healthcare institutions. 14

Another important finding of this study which is consistent with the reports of the literature is the additional risk in patients undergoing emergency surgical procedures (unscheduled). Our study found that, in the group of patients taken to a surgical procedure, 54.74% underwent unscheduled surgery because of the severity of their condition which required emergent intervention. The cumulative incidence of REs in this group of patients was 31.57% (95% CI 95% [21.38; 43,25]). The study by Guevara et al16 in 2013 in patients taken to emergency surgery concluded that the risk of reintervention and mortality is greater in this population and this, in turn, favors the REUE occurrence.

As far as preventability is concerned, the incidence of preventable REUEs was 8.91% (95% CI [5.36; 13.71]), representing 75% of the total number of REUEs. In previous studies conducted by the same group of researchers of this study, 11 a 61% incidence of preventable REUEs was reported in 3 Colombian institutions. On the other hand, other references such as the Canadian study by Baker, (6 Zegers, 14 or the study by Healey et al, 23 conducted specifically in surgical patients, reported a proportion of preventable REUEs between 36.9% and 46.8%. The degree of preventability of REUEs points to the fact that, despite advances in their identification and analysis, risk management, and prevention strategies appear to be insufficient or not very effective. Consequently, proposals for risk prevention are needed within the framework of risk management systems of proven effectiveness, and further studies are a priority.

Mortality associated with REs in our study was 4.16% (1/ 24) (95% CI [0.10; 21.1]), similar to the incidence of disability secondary to REs. In both cases, these outcomes occurred as a result of non-preventable REs. In the IBEAS study (Prevalence of adverse effects in Latin American hospi-tals), 9 the reported mortality range was 3.3% to 13.5%, while the reported range for disability was 5.2% to 36.8%, showing similar values.

Regarding the analysis of REUE performed by means of the application of the London protocol, the following contributing factors were identified: patient-related factors (58.33%), clinical context-related factors and factors related to scheduled tasks (50.00%). There is a correlation between these factors and the complexity of the conditions seen at the institution, comorbidities, and factors previously described, such as age. In terms of human factors, particularly communication failures, the data are found to correlate with those in the literature, reported at 65%.14 It is important to mention that communication refers to information that is conveyed accurately and consistently as a result of comprehension.24

Along the same lines, communication errors involved in the occurrence of REUE may be associated with social structures and organization factors. 25 Another result which is consistent with the above is the report by Joint Commission on Accreditation of Healthcare Organizations, which documented that poor communication was responsible for 60% of medical errors, 75% of which resulted in death. 18

Being a prospective cohort, this study allowed to create opportunities for real-time impact on the consequences for patients who experienced a RE of unwanted effects. Another important consideration is the 30-day prospective follow-up after discharge from the institution, which is interesting in that it allowed to recognize an important number of healthcare-related REUEs occurring beyond tight control from healthcare providers. This result must also give rise to a judicious reflection about the need for adequate follow-up of patients beyond the walls of the institution and to keep them under remote responsibility of the treating physicians. It also leads to the reflection that care responsibilities do not exist only while the patient is in the hospital or any other healthcare institution, and that all decisions made may result in an REUE within the short, medium or long term.

A limitation of this work is the source of information, mainly the clinical records, which means that the results depend on the quality of the documentation.

The results of this study show REUE incidence, prevent-ability and contributing factors in surgical services within the frequency ranges reported in the international literature. The high frequency of preventable REUEs is an opportunity for improvement by means of the implementation of clinical risk management systems. Moreover, patient-related factors such as the condition leading to admission, age and comorbidities appear to be related with a higher number of REUEs, but further studies are required in order to measure the degree of association.

The study provides relevant information regarding REUEs in the surgery service, characteristics of the patients in whom they occurred, and data regarding the circumstances in which the events occurred. This characterization of the site, time to REUE and contributing factors identified with the London protocol allows this study to not just report figures, but to be used as input for risk management plans in healthcare institutions of similar characteristics as those of the institution studied.

Human and animal protection: The authors declare that no experiments were conducted in humans or animals for this research.

Data confidentiality: The authors declare having followed the protocols of their institution regarding patient data disclosure.

Right to privacy and informed consent: The authors declare that no patient data appear in this article.