Preoperative screening and testing for COVID-19 during Victoria's second wave.

Preoperative screening for clinical and epidemiological risk factors has been an important component of perioperative care during the coronavirus disease 2019 (COVID‐19) pandemic. In March and April 2020, Victoria developed a screening checklist to identify patients at risk of COVID‐19.1, 2 This checklist was intended to protect patients undergoing surgery and minimise the risk of spreading COVID‐19 to perioperative teams. The use of this checklist was evaluated during April and May, on the back of Victoria's first COVID‐19 wave. All 152 (7%) of 2197 patients screening positive returned a negative swab result for coronavirus disease when tested by reverse transcription polymerase chain reaction (RT‐PCR). However, actual documentation of the use of the screening questionnaire was under 75%, suggesting use of the screening checklist alone might fail to protect some patients and their perioperative healthcare workers (HCWs).

Evidence from overseas has suggested there is a considerable morbidity and mortality risk facing patients undergoing surgery with co‐existent severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection, particularly when the patient has cancer. The evidence from the limited number of studies published in 2020 suggests a mortality following elective surgery of 18%, and over 25% in those undergoing emergency procedures. Although these rates were not experienced during the first or second COVID‐19 waves in Victoria, there is insufficient local Victorian evidence due to the relatively low numbers of cases that have undergone surgery with concurrent SARS‐CoV‐2. It is to be hoped that the Victorian perioperative sector will document its collective experience of surgical morbidity in patients with SARS‐CoV‐2 infection more fully in the coming months.

In June 2020, whilst the second Victorian wave of COVID‐19 was emerging, other Australian States and Territories were experiencing almost no cases of local (community) transmission. A multicentre Australian study conducted in 11 hospitals across four States (including Victoria) over 6 weeks from the beginning of June, evaluated the results of intraoperative nasopharyngeal swabs and serology from 3010 elective surgery patients. No swab returned RT‐PCR positive results (Bayesian estimated prevalence of active infection 0.02%), but positive IgG serology was found in 15, five of which were strongly positive (Bayesian estimated seroprevalence, 0.16%). This provides important evidence that when the community prevalence is low, routine preoperative RT‐PCR testing on asymptomatic, screened negative patients, is unlikely to provide further reassurance.

However in July 2020, some local government areas (LGAs) in metropolitan Melbourne were experiencing a daily incidence of over 20/100 000, with community prevalence rates of 100–1000 per 100 000 population. This issue of the journal, also reports the results of preoperative testing for eight Victorian hospitals, which included in their catchment a number of high incidence LGAs during the peak of the July–August second COVID‐19 wave. The rate of one in 833 (0.12%) elective surgery cases represents four asymptomatic patients in a cohort of 4965. Of the other four patients testing positive, one was symptomatic and had their surgery postponed, whilst three asymptomatic patients with a preoperative negative RT‐PCR who developed symptoms in the post‐operative period then tested positive, but suffered no complications. Other countries, far worse afflicted by their waves of coronavirus disease than Victoria, have reported rates of preoperative testing exceeding 1%.

There are three reasons to identify which patients being admitted to hospital for elective surgery have coronavirus disease. The first is to minimize their risk of morbidity and mortality in the post‐operative period. Second, to safeguard nursing, anaesthesia and surgical teams as well as other HCWs from infection and/or furlough through the wearing of appropriate personal protective equipment. The Victorian second wave resulted in 3573 clinically facing HCWs infected, including 210 medical practitioners and 1352 nurses or midwives. Almost three quarters of infections (n = 2604) were acquired in the workplace, although aerosol‐generating behaviours in poorly ventilated wards proved higher risk than aerosol‐generating procedures performed in the operating theatre which has 20–40 air changes per hour. Nurses, anaesthetists and surgeons were certainly infected in the course of their work during Victoria's second wave, despite none being in the preoperative testing cohort reported by the eight Victorian hospitals. There were also 596 non‐clinical staff infected, 343 (58%) of them were acquired in the workplace. The third risk is to other patients who may contract coronavirus disease in hospital by coming into contact with infected patients.

The perioperative response to the COVID‐19 pandemic needs to ensure that, when faced with a surge in cases, there are a number of controls to protect patients and HCWs, and that each is done well, rather than relying on one single defence. The preoperative screening checklist is the first line of defence, but it is not always done perfectly. For this reason, when Victoria was facing its second wave, the Minister of Health introduced preoperative RT‐PCR testing for all Victorians undergoing emergency and elective surgery under general anaesthetic. Testing prior to elective surgery was to be conducted within 7 days of surgery, with post‐testing self‐isolation a third line of defence. Although the study published by Myles et al. was focused on elective surgery, emergency patients were also tested throughout Victoria. As these represent a different type of patient, the results of preoperative testing for emergency patients will certainly help inform the future response.

In November 2020, the COVIDSurg collaborative reported their findings from an international cohort study – preoperative testing for elective cancer surgery significantly reduced the rate of post‐operative pulmonary complications from 4.2% (no preoperative test, n = 6482) to 2.8% (with preoperative test, n = 1481). They stratified healthcare providers into high risk and low risk based on 25/100 000 case notifications over a 14‐day period. Hospitals in high‐risk areas reported a lower complication rate with preoperative testing for both major and minor procedures. Even hospitals serving low‐risk communities had a significantly reduced risk of complications with preoperative RT‐PCR testing following major but not minor surgery.

RT‐PCR testing remains the gold standard, although the result needs to be interpreted with an appreciation of the risk of false‐negative and false‐positive rates. With swab RT‐PCR tests, false negatives occur in 2–29% (sensitivity of 71–98%), in part influenced by viral load and sampling technique. With asymptomatic testing, false positives become more likely than true positives when the community prevalence is low, which is why preoperative testing, particularly when combined with self‐isolation before surgery, is unlikely to be of value when community prevalence falls below 1/10 000. The requirement for self‐isolation adds an additional financial and social burden to the patient awaiting elective surgery. When the risk is low, Myles et al. appropriately recommend a screening checklist should be sufficient to identify patients with clinical or epidemiological risk factors for SARS‐CoV‐2, and who should then be tested. The screening checklist has also been updated to include a question on previous SARS‐CoV‐2 infection, and the need to consider the possible clinical impact of ‘long COVID’ on any planned surgery including giving consideration to delaying the procedure. If further waves of COVID‐19 occur in the future, then peroperative testing and self‐isolation can easily be added by health services as additional safefguards for surgical patients and healthcare workers as part of theescalation response (which needs to be rapid) to a rise in community prevalence.

Author Contributions

David Watters: Conceptualization; writing‐original draft; writing‐review and editing.