What was the Prevalence of COVID-19 in Asymptomatic Patients Undergoing Orthopaedic Surgery in One Large United States City Mid-pandemic?

Abstract

Background: Many patients with coronavirus disease 2019 (COVID-19) are asymptomatic. The prevalence of COVID-19 in orthopaedic populations will vary depending on the time and place where the sampling is performed. The idea that asymptomatic carriers play a role is generalizable but has not been studied in large populations of patients undergoing elective orthopaedic surgery. We therefore evaluated this topic in one large, metropolitan city in a state that had the ninth-most infections in the United States at the time this study was completed (June 2020). This work was based on a screening and testing protocol that required all patients to be tested for COVID-19 preoperatively.

Questions/purposes: (1) What is the prevalence of asymptomatic COVID-19 infection in patients planning to undergo orthopaedic surgery in one major city, in order to provide other surgeons with a framework for assessing COVID-19 rates in their healthcare system? (2) How did patients with positive test results for COVID-19 differ in terms of age, sex, and orthopaedic conditions? (3) What proportion of patients had complications treated, and how many patients had a symptomatic COVID-19 infection within 30 days of surgery (recognizing that some may have been missed and so our estimates of event rates will necessarily underestimate the frequency of this event)?

Methods: All adult patients scheduled for surgery at four facilities (two tertiary care hospitals, one orthopaedic specialty hospital, and one ambulatory surgery center) at a single institution in the Philadelphia metropolitan area from April 27, 2020 to June 12, 2020 were included in this study. A total of 1295 patients were screened for symptoms, exposure, temperature, and oxygen saturation via a standardized protocol before surgical scheduling; 1.5% (19 of 1295) were excluded because they had COVID-19 symptoms, exposure, or recent travel based on the initial screening questionnaire, leaving 98.5% (1276 of 1295) who underwent testing for COVID-19 preoperatively. All 1276 patients who passed the initial screening test underwent nasopharyngeal swabbing for COVID-19 via reverse transcription polymerase chain reaction before surgery. The mean age at the time of testing was 56 ± 16 years, and 53% (672 of 1276) were men. Eighty-seven percent (1106), 8% (103), and 5% (67) were tested via the Roche, Abbott, and Cepheid assays, respectively. All patients undergoing elective surgery were tested via the Roche assay, while those undergoing nonelective surgery received either the Abbott or Cepheid assay, based on availability. Patients with positive test results undergoing elective surgery had their procedures rescheduled, while patients scheduled for nonelective surgery underwent surgery regardless of their test results. Additionally, we reviewed the records of all patients at 30 days postoperatively for emergency room visits, readmissions, and COVID-19-related complications via electronic medical records and surgeon-reported complications. However, we had no method for definitively determining how many patients had complications, emergency department visits, or readmissions outside our system, so our event rate estimates for these endpoints are necessarily best-case estimates.

Results: A total of 0.5% (7 of 1276) of the patients tested positive for COVID-19: five via the Roche assay and two via the Abbott assay. Patients with positive test results were younger than those with negative results (39 ± 12 years versus 56 ± 16 years; p = 0.01). With the numbers available, we found no difference in the proportion of patients with positive test results for COVID-19 based on subspecialty area (examining the lowest and highest point estimates, respectively, we observed: trauma surgery [3%; 2 of 68 patients] versus hip and knee [0.3%; 1 of 401 patients], OR 12 [95% CI 1-135]; p = 0.06). No patients with negative preoperative test results for COVID-19 developed a symptomatic COVID-19 infection within 30 days postoperatively. Within 30 days of surgery, 0.9% (11 of 1276) of the patients presented to the emergency room, and 1.3% (16 of 1276) were readmitted for non-COVID-19-related complications. None of the patients with positive test results for COVID-19 preoperatively experienced complications. However, because some were likely treated outside our healthcare system, the actual percentages may be higher.

Conclusion: Because younger patients are more likely to be asymptomatic carriers of disease, surgeons should emphasize the importance of taking proper precautions to prevent virus exposure preoperatively. Because the rates of COVID-19 infection differ based on city and time, surgeons should monitor the local prevalence of disease to properly advise patients on the risk of COVID-19 exposure. Further investigation is required to assess the prevalence in the orthopaedic population in cities with larger COVID-19 burdens.

Level of evidence: Level III, therapeutic study.

Fig. 1

The preoperative COVID-19 screening questionnaire for COVID-19 symptoms and exposure is shown.

Fig. 2

This flowchart shows the study population screened and tested for COVID-19 preoperatively.