Approximately 30% of the global burden of disease is attributable to conditions that require a surgical procedure.1 In countries such as Mexico, the SARS-CoV-2 pandemic had a major impact on the number of surgical procedures that were canceled due to competing roles and responsibilities among the clinical staff, resulting in a 30% decrease in surgical procedures from 2019 to 2020.2,3 Of the surgical procedures performed between 2019 and 2020, 40% resulted in postoperative complications.4–8 The preoperative evaluation of patients aims to minimize risk factors and reduce postoperative complications (POC),9 through the use of various techniques and diagnostic tests. POC can increase postoperative morbidity and mortality by 15–30% and prolong hospital stay.7 The Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) is a clinical tool used for preoperative evaluation, which considers the following seven factors: age, pulse oximetry, respiratory infection within 30 days of surgery, preoperative anemia, site of surgery, duration of surgery, and whether the surgery is elective or emergency.10 A specific level is assigned to each patient based on a scale of low-, moderate-, and high-risk. The ARISCAT scale has been validated in a multicenter study and other research studies, which found an association between the three risk levels and an POC incidence of 3%, 13% and 38%, respectively.11–13

Preoperative spirometry is the gold standard for diagnosing airway flow obstruction and is a critical clinical tool to qualify the response to treatment over time.14 Some studies have found that spirometry helps to predict POC,15,16 while other authors report that adequate treatment for bronchial asthma and COPD reduce POC.17,18 The occurrence of POC in patients with abnormal spirometry can increase up to 30%, compared to patients with normal spirometry.19,20

Despite the extensive evidence regarding the validity of the ARISCAT risk scale10,11 and the benefits of preoperative spirometry,14–22 current guidelines for preoperative care in Mexico recommend that preoperative spirometry should only be performed on patients with a pulmonary disease diagnosis.23 Although the combination of preoperative spirometry and the ARISCAT scale has been found to improve patient outcomes by reducing POC and mortality,10–13 this is the first study to evaluate this strategy in Mexico. Our study aimed to determine if preoperative spirometry can prevent POC and improve survival at each ARISCAT risk level at one of the largest public hospitals in Mexico City, the Hospital General de México.

We identified 2059 patients who had an ARISCAT assessment during the period of 2013–2017 and compared the incidence of POC and mortality in the groups with and without spirometry. Our hypothesis was that the combined use of preoperative spirometry and the ARISCAT scale would be associated with a reduced number of POC and lower mortality.

This study compared the risk factors as well as the incidence of POC and mortality among Mexican adults who did or did not undergo preoperative spirometry, based on their ARISCAT risk level. Our findings indicate that the combined use of spirometry and the ARISCAT risk assessment tool is an effective strategy to reduce POC and mortality in patients who are undergoing elective surgery in Mexico. Of particular significance is the fact that patients with a high-risk ARISCAT level who did not receive a spirometry assessment (Group 2) had the higher incidence of POC (45%) and mortality (18%), which is a clear indication that these patients are not being evaluated adequately prior to surgery. An explanation for this may be that because these patients did not undergo spirometry their preoperative risk was not determined, which resulted in a greater risk of POC, compared to patients who did undergo a spirometry assessment. Conversely, patients with a high-risk ARISCAT level who received a spirometry evaluation had a significantly lower incidence of POC (2%) and mortality (0.4%).

Patients with lung disease have an increased risk of POC, and several studies have reported that the incidence of POC among patients with lung disease can range from 19% to 40%.17,20–22,26,27 In the present study, we found a lower rate of POC among the COPD patients who had a spirometry assessment (3%), compared to those without spirometry (35%). Since patients who did not undergo spirometry had no documented history of lung disease in their medical record, it is possible some of these patients may have had undiagnosed lung disease that was not being treated or accounted for prior to surgery, thus increasing their risk of POC.

A restrictive spirometry pattern is also associated with POC, which can range between 21.1% and 43.2%.15,28 In our study, the incidence of pulmonary POC was highest among patients who did not receive a spirometry test and had a high ARISCAT risk level (35%). Of the POC we observed, pulmonary POC were more frequent among patients with restrictive diseases, compared to patients who had airflow obstruction. Our multivariate analyses indicate that being male, not undergoing spirometry, increasing ARISCAT risk, and having a major surgery were significantly associated with POC. Other studies found that being 65 years or older, receiving an abnormal spirometry result, undergoing upper abdominal surgery, being an active smoker, having lung disease, and a high or moderate ARISCAT risk level are significant risk factors for POC.12,13,19,29,30

The results of a recent study indicate that POC are associated with a 30-day mortality of 1.5% and a 90-day mortality of 2.8%.31 A literature review by Elmer et al. reports that after esophagectomy, mortality increased by 22% among patients with COPD, and spirometry was a good predictor of mortality risk.32 Gómez-Hernández et al. also found that nearly 23% of patients who had major complications and died after surgery were mainly due to respiratory failure.33 Schussler et al. reported a mortality of 19% in patients with COPD, depending on the extent of their lung resection.34 Our findings suggest that the use of spirometry, especially among high-risk patients, could help to reduce mortality by also lowering the probability of POC. Additionally, our result indicate that having an oncological surgery is a significant risk factor for increased mortality, and these findings are supported by other studies.19,26,29

This study has some limitations. The patient data used for this research was obtained from a single hospital, which limits the generalizability of our results. However, since all patient medical records were reviewed at the HGM (over 9000 records) to identify a sample of 2059 patients who had a preoperative evaluation and underwent surgery from 2013 to 2017, the internal validity of our findings is likely strong, especially regarding the patients undergoing surgery at the HGM. Additionally, we used the same criteria as the PERISCOPE study (Prospective Evaluation of a Risk Score for Postoperative Pulmonary Complications in Europe)10 to assess risk of postoperative pulmonary complications. This risk scale has strong internal and external validity because it is based on a large (n=5099), prospective, and observational study that was conducted at 63 hospitals in 21 European cities.11 Also relevant, is the fact that spirometry is currently considered the gold standard to detect airflow obstruction. Nonetheless, future studies should evaluate the use of spirometry and the ARISCAT scale at other hospitals that are part of the Mexican Ministry of Health and other medical organizations in Mexico, to improve the generalizability and external validity of these results. Although some information about patient comorbidities was included in study (obesity, smoking history, pulmonary disease, and diabetes), we did not include other comorbidities such as cardiovascular disease, which is associated with an increased morbidity and mortality risk after surgery. Another limitation is the possibility that some of the high-risk patients at the HGM are not being referred for preoperative assessment due to the overscheduling of services at the Department of Pulmonary Physiology, and to prioritize surgical appointments. Our findings indicate that patients who received a spirometry evaluation had a lower ARISCAT risk than patients who did not undergo spirometry, who were more likely to have a high ARISCAT risk. Also, although current guidelines in Mexico recommend spirometry in patients with pulmonary disease, in our sample it was performed in 67% of patients with no pulmonary disease. This is because there is currently no triage system to prioritize patients who might be at higher risk of postoperative complications. While these limitations may result in a selection bias that may have affected our results, it also highlights the urgent need to develop better protocols for the preoperative evaluation of high-risk patients at the HGM. An aim of this study is to showcase the importance of systematizing the use of the ARISCAT risk scale to help facilitate the identification of high-risk patients who should undergo spirometry during their preoperative evaluation.

Despite these limitations, to the best of our knowledge, this comprehensive study was the first to examine the effectiveness of using preoperative spirometry and the ARISCAT risk scale to help reduce POC and mortality in Mexico. The ARISCAT scale is a low-cost clinical tool that is easy to perform and to interpret, since it accounts for factors that are strongly associated with POC, such as the site and duration of surgery. However, the ARISCAT assessment does not determine whether the patient has chronic pulmonary disease, because it only considers if the patient has had a respiratory infection within 30 days of surgery. Performing preoperative spirometry in patients who have a moderate or high ARISCAT risk is an effective way to assess the functional respiratory status of higher risk patients, since lung disease is associated with increased pulmonary POC, as well as cardiovascular and vascular POC.35 Two significant objectives are achieved by combining these two diagnostic tests, first, to improve the quality of preoperative care, and second, to ensure that the highest risk patients are undergoing preoperative spirometry to reduce the probability of POC and mortality. In addition, has also proven to be a cost-saving strategy.36,37

Spirometry is a common preoperative test in high-income countries, but in low- or middle-income countries such as Mexico, it is still an accessible test only in second and third level hospital centers. As clinicians are faced with an increasing number of pulmonary complications among patients who had COVID-19, the combined use of spirometry and the ARISCAT risk scale is an important strategy to improve the quality of preoperative patient evaluations, reduce POC and mortality, and to optimize health care resources, especially in resource-limited countries such as Mexico. As evidenced by our results, we would suggest that the following clinical recommendations be implemented in Mexico: (1) Provide training and guidance to health personnel regarding the importance of conducting a preoperative assessment, which includes identifying the patient's ARISCAT risk level. (2) Perform preoperative spirometry in patients who have a moderate and high ARISCAT risk, or will be undergoing major surgery, or an oncology-related surgery. An ARISCAT assessment is simple, low-cost, and can be conducted quickly, which make it an ideal clinical tool to identify the patients who would benefit the most from preoperative spirometry. This first step would help to identify patients who might have respiratory problems, so that any underlying pulmonary disease could be managed prior to surgery, thus minimizing any postoperative risks and complications. These two actions will improve the quality of preoperative care and will lead to significant clinical benefit for surgical patients by identifying those who are at greatest risk of postoperative complications. In addition to improving patient outcomes, these recommendations will also help to optimize the use of resources, which are scarce in all health systems, but especially in low- and middle-income countries, like Mexico.

In summary, our findings suggest that the combined use of preoperative spirometry and the ARISCAT scale can help to reduce POC and mortality. The findings of this study should be used to revise and update the current guidelines and health policies for preoperative procedures in Mexico. Preoperative spirometry should also be recommended for patients who have a medium or high ARISCAT risk level.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Yolanda Mares-Gutiérrez has contributed as principal investigator in the original idea, design of the study, administrative support, provision of study materials or patients, collection, assembly and data curation, analysis and interpretation, manuscript writing, review, and final approval.

Adrián Martínez-González has contributed as a collaborating author in the design of the study, administrative support, analysis and interpretation, manuscript writing, review and final approval.

Guillermo Salinas-Escudero has contributed as a collaborating author in the design of the study, analysis and interpretation, manuscript writing, review and final approval.

Manuel García-Minjares has contributed as a collaborating author in the data analysis and interpretation, manuscript writing, review, and final approval.

Stephanie Liu has contributed as a collaborating author in the review, and final approval.

Yvonne N. Flores has contributed as principal investigator in the original idea, design of the study, administrative support, provision of study materials or patients, collection, assembly and data curation, analysis and interpretation, manuscript writing, review, final approval, and corresponding author.

The authors declare no conflict of interest in submitting this manuscript for publication.