Prevalence of SARS-CoV-2 infection in asymptomatic preoperative patients

INTRODUCTION

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection still maintains its clinical importance. Emerging new variants threaten immunocompromised people and vulnerable populations. According to world health organization reports, more than 769 million cases and nearly seven million deaths have occurred in different age groups worldwide due to SARS-CoV-2 infection in the COVID-19 pandemic.¹

Globally, various confinement measures have been implemented to stop the spread of SARS-CoV-2 infection during the pandemic. One of these restrictive measures applied in our country in March 2020 was the suspension of elective surgery.² However, surgeries that could not be postponed were performed on emergency and trauma patients as well as oncology patients in many centres during the pandemic period. The process and management of elective surgical operations differed between health centres.^3-6 Evaluation of preoperative diagnostic tests have been an important point in reducing the risk of asymptomatic transmission to healthcare personnel during the COVID-19 pandemic period. In the early period of the pandemic, radiological tests (chest X-ray or chest computed tomography) and microbiological tests (SARS-CoV-2 reverse transcription polymerase chain reaction (RT-qPCR) and antigen tests) were performed by researchers in screening preoperative patients.^7-9 Among these diagnostic tests, the real-time polymerase chain reaction (RT-qPCR) test has been recommended by the World Health Organization as the primary diagnostic test in detecting asymptomatic and symptomatic patients with suspected COVID-19.¹⁰ RT-qPCR test become a common diagnostic test used all over the world. Screening of asymptomatic preoperative patients is very important not only in protecting healthcare personnel but also in preventing nosocomial infections and in protecting patients with deficient or suppressed immune systems. It has been emphasized in many studies that the presence of this infection in preoperative patients should not be ignored to prevent the transmission of hospital-acquired SARS-CoV-2 infection during the pandemic period.^11-13

The aim of current study was to retrospectively evaluate prevalence of SARS-CoV-2 infection in asymptomatic preoperative patients during the pandemic period.

METHODS

In this study, the results of Rt-qPCR assay for detection of SARS-CoV-2 infection in asymptomatic preoperative patients at Mersin university hospital were retrospectively evaluated. A total of 3773 asymptomatic preoperative patients among 23385 patients with suspected COVID-19 who underwent Rt-qPCR test between 25/02/2022 and 20/05/2022 were retrospectively included in the study.

RT-qPCR test

For COVID-19 laboratory diagnosis, nasopharyngeal and oropharyngeal swab specimens collected from preoperative patients were placed in tubes containing viral nucleic acid buffer (vNAT). RT-qPCR test of the viral RNAs isolated with vNAT solution was performed. The DS CORONEX COVID -19 PCR test (Ver.2.0, DS bio and nano technology, Turkiye) kit used for the RT-qPCR. PCR test targets the N and Orf1ab gene region specific for SARS-CoV-2. RT-qPCR assays were performed using Qiagen Rotor-Gene with manufacturer's recommended protocol. All PCR reactions were performed using the Q5plex real-time PCR instrument.

Statistical analysis

Statistical analyses were performed using the statistical software IBM SPSS (version 20, Armonk, NY: IBM Corp). The chi-square test and Fisher's exact test were used to analyse the categorical variables in the study. P cutoff value for statistical significance was taken as 0.05.

RESULTS

Of the 23385 COVID-19 suspected patients tested during the study period, 3773 were patients who underwent SARS-CoV-2 testing prior to surgery. As a result of RT - qPCR performed on 23385 COVID-19 patients suspected of having SARS-CoV-2 infection, 4593 (19.7%) of the patients were found to be positive. Among the SARS-CoV-2 positive patients, 86 (2.3%) were found to be preoperative. Of the 3773 asymptomatic preoperative patients included in the study, 1946 (51.6%) were women and 1827 (48.4%) were men. Statistical analysis showed that there was no significant difference between the genders (p=0.88). The mean age of the preoperative asymptomatic patients was 47.5±22.5. There was no statistically significant difference between patients over 18 years (89.7%) and under 18 years (10.3%) (p=0.163) (Table 1). Distribution of preoperative SARS-CoV-2 positive patients according to clinics were 7.1% (n=7) thoracic surgery, 3.7% (n=7) neurosurgery, 3.5% (n=16) otolaryngology, 2.6% (n=12) general surgery and 2.4% (n=11) urology clinic, respectively (Table 2). There was a statistically significant difference between the clinics (p=0.014) and the highest rate of SARS-CoV-2 positive preoperative patients was in the thoracic surgery clinic (7.1%, p=0.006). Of the asymptomatic preoperative patients, 30% were inpatients and 70% were outpatients. Among these patients, the rate of SARS-CoV-2 positive outpatients was 1.9%, while this rate was 3.2% inpatients, and a statistically significant difference was found between inpatients and outpatients (p=0.015), 98.2% of asymptomatic preoperative patients were elective surgery patients and 1.8% were emergency surgery patients. Among these patients, the rate of emergency surgery patients positive for SARS-CoV-2 infection was 10.1%, whereas the rate of elective surgery patients was 2.1%. There was a statistically significant difference between the two groups (p=0.001).

As a result of study, it was found that SARS-CoV-2 positivity was significantly lower in pre-op patient group than in COVID-19 patients whose routine test results were positive for other reasons (2.3%/ 23.1%; p<0.0005).

DISCUSSION

In the early days of the pandemic, there was insufficient data on the prevalence and classification of SARS-CoV-2 infection in the preoperative patient group. In addition, it remained unclear whether non-urgent surgeries should be postponed in all patients with confirmed or suspected SARS-CoV-2 infection during pandemic period. Besides, researchers have also reported that risk of postoperative complications and mortality is high in preoperative patients with severe SARS-CoV-2 infection.¹⁴

The high contagiousness of SARS-CoV-2 infection, the long incubation period and the non-specific symptoms at the onset of the disease have led to difficulties in diagnosing COVID-19 in preoperative asymptomatic patients and patients in the incubation period. Since the non-existing of COVID-19 symptoms in the preoperative asymptomatic patient group does not exclude SARS-CoV-2 infection, routinely used RT-qPCR tests are important for both healthcare personnel and immunocompromised patients to prevent the transmission of SARS-CoV-2 infection.

In the later stages of the pandemic, the number of surgical operations performed declined due to the increasing demand for hospitalization for patients with COVID-19 in healthcare institutions.^5,15 Due to recurrent peaks in the pandemic, the decline in elective surgical procedures in particular continued, and long waiting times affected patient prognosis. Therefore, RT-qPCR testing was primarily used to detect SARS-CoV-2 infection when planning elective surgeries in many healthcare facilities during the pandemic.

The positivity rate in asymptomatic preoperative patients varies in different studies performed in the literature. Iglesias et al reported a positivity rate of the SARS-CoV-2 RT -qPCR test of 0.27% in 363 preoperative patients, whereas Al-Khersan et al reported 0.88% in 114 patients.^4,16 In one multicenter study researchers reported this rate as 7.8% in asymptomatic preoperative patients.¹¹ However, in another study, this rate was reported as 0.474%, and it was suggested that this was related to the low rate of COVID-19 positive patients in the region where the study was conducted.¹⁷ In addition, several studies have reported RT -qPCR test positivity rates in the asymptomatic preoperative pediatric patient population ranging from 0.93% to 2.56%.^18-20 Moreover, in a meta-analysis study evaluating preoperative asymptomatic patients have been reported that the positivity for SARS-CoV-2 infection ranged from 0.00% to 9.49% and the overall percentage was 0.76%.²¹ In our study, Rt-qPCR test positivity in the asymptomatic preoperative patient group was determined to be lower (2.3%) than the other patient group (23.1%) who were routinely Rt-qPCR positive for other reasons.

Islam et al reported a positivity rate of SARS-CoV-2 RT-qPCR test of 12.5% in 514 preoperative asymptomatic orthopedic patients.²² In addition to this, researchers detected that the age and gender ratios in the SARS-CoV-2 infection-positive asymptomatic preoperative patient group showed a statistically significant difference from the negative group. According to this, they reported that the higher positivity rates were determined in the younger age and female patients. In contrast to this study, no significant difference was found between SARS-CoV-2 infection positivity and age and gender in our study (p=0.88; p=0.163). Nevertheless, Muhammed et al reported positive SARS-CoV-2 infection in 14 (9.3%) of 150 asymptomatic preoperative ophthalmology patients.²³ Similar to our study, they did not find a statistically significant relationship between age groups and gender in the group of COVID-19 positive asymptomatic preoperative patients.

When the clinics where asymptomatic preoperative patients positive for SARS-CoV-2 infection were evaluated, it was determined that there was a statistically significant difference between the departments in the current study. The clinic with the highest rate of positive preoperative patients was determined to be thoracic surgery (7.1%, p=0.006). Similar to our study the rate of SARS-CoV-2 positive preoperative asymptomatic patients admitted to thoracic surgery was reported as 9.37%.²⁴ The researchers suggested that this could be due to exacerbation of a previous lung infection as a result of surgical trauma and general anesthesia, which increases susceptibility to SARS-CoV-2 infection. Another study reported that elderly lung cancer patients may be more likely to develop COVID-19 pneumonia before surgery due to weakened immune system and decreased physical resistance.²⁵ We supposed that the incidence of SARS-CoV-2 infection in patients from this department was high due to the routine control measures performed in thoracic surgery patients before surgery in the current study.

The prevalence of positive SARS-CoV-2 infection in asymptomatic preoperative patients varies in the different regions and health facilities of the studies conducted. This may be due to the practicability of routine pre-screening tests, demographic characteristics of the patients and co-morbid factors. In the case of a similar pandemic in asymptomatic preoperative patients, applying RT-qPCR pre-screening tests will help control the epidemic by minimizing the risk of transmission of SARS-CoV-2 infection, especially to healthcare personnel. Management of preoperative asymptomatic COVID-19 patients requires a multidisciplinary approach. In particular, the prevalence of preoperative asymptomatic COVID-19 cases has implications for patient safety, healthcare staff protection, and surgical planning. The wide range of reported prevalence rates demonstrates the importance of standardized testing protocols and patient screening. Accurate estimation of prevalence is critical for making informed decisions about resource allocation, infection control measures, and delays in operations.

Limitations

This study was single-centre and included patients over a short period of time.

CONCLUSION

Rt-qPCR test positivity in the asymptomatic preoperative patient group was determined as 2.3% in this study. Although SARS-CoV-2 positivity was lower in the preoperative patients, this rate never excludes pre-screening of asymptomatic preoperative patients. We suggest that applying pre-screening tests to asymptomatic preoperative patients is significant in protecting healthcare personnel and patients with deficient or suppressed immune systems and also preventing nosocomial infections.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the Institutional Ethics Committee of Mersin University (Date: 20/07/2022 and Decision No: 2022/498).

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