Assessment of Sensitivity and Specificity of Patient-Collected Lower Nasal Specimens for Sudden Acute Respiratory Syndrome Coronavirus 2 Testing

Since the emergence of the sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak in Wuhan, China, in December 2019, the virus has spread to 173 countries, resulting in 3 855 788 confirmed cases and 265 862 deaths as of May 9, 2020.1 Stanford Health Care was one of the first nonfederal facilities to obtain US Food and Drug Administration approval for a proprietary test using reverse transcriptase–polymerase chain reaction for SARS-CoV-2 using nasopharyngeal and oropharyngeal specimens on March 2, 2020. However, specimen collection must be done by health care workers and requires extensive use of personal protective equipment. To minimize the risk of exposure during testing, reduce personal protective equipment use, and increase access to testing, we compared the diagnostic equivalence of a modified specimen collection method, patientcollected lower nasal swabs, with that of the current clinical standard, health care worker–collected oropharyngeal swabs. If the 2 methods proved to be diagnostically equivalent, patients would be able to collect specimens themselves without exposing health care workers to respiratory secretions.


Introduction
Since the emergence of the sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak in Wuhan, China, in December 2019, the virus has spread to 173 countries, resulting in 3 855 788 confirmed cases and 265 862 deaths as of May 9, 2020. 1 Stanford Health Care was one of the first nonfederal facilities to obtain US Food and Drug Administration approval for a proprietary test using reverse transcriptase-polymerase chain reaction for SARS-CoV-2 using nasopharyngeal and oropharyngeal specimens on March 2, 2020. However, specimen collection must be done by health care workers and requires extensive use of personal protective equipment. To minimize the risk of exposure during testing, reduce personal protective equipment use, and increase access to testing, we compared the diagnostic equivalence of a modified specimen collection method, patientcollected lower nasal swabs, with that of the current clinical standard, health care worker-collected oropharyngeal swabs. If the 2 methods proved to be diagnostically equivalent, patients would be able to collect specimens themselves without exposing health care workers to respiratory secretions.

Methods
This prognostic study was approved by the Stanford University institutional review board.
Participants provided oral informed consent to clinical research coordinators and then signed a consent form with the physician who collected the oropharyngeal swab. This study complies with the Standards for Reporting of Diagnostic Accuracy (STARD) reporting guideline.
The target population was Stanford Health Care outpatients with a reverse transcriptasepolymerase chain reaction test that was positive for SARS-CoV-2 in March 2020. We included a convenience sample of patients who consented to be contacted by our study staff. Our study staff obtained informed consent remotely, to minimize exposure of research staff to infected patients and to reduce the duration of study visits, and sent instructional materials electronically. Health care workers were excluded because of their familiarity with specimen collection, as were patients enrolled in drug trials for SARS-CoV-2.
After informed consent was obtained, participants were scheduled to return to Stanford Health Care for drive-through collection of 3 specimens using a patient-collected lower nasal swab (Puritan We report participant demographic characteristics, sensitivity and specificity, and discordant probabilities with 95% binomial CIs of patient-collected lower nasal compared with physiciancollected oropharyngeal specimens. All analyses were performed with SAS statistical software version 9.4 (SAS Institute). Data analysis was performed in May 2020.    Table 1).

JAMA Network Open | Infectious Diseases
We observed diagnostic equivalence across the 3 methods of specimen collection ( Table 2).
Eleven participants (37%) had test results that were positive for SARS-CoV-2 across patient-and physician-collected specimens, and 18 participants (60%) had results that were negative for SARS-CoV-2 across patient-and physician-collected specimens. The only discordant result was a participant whose self-collected nasal specimen tested positive, whereas both of their physiciancollected specimens tested negative (3.30%; 95% CI, 0.08%-17.00%). The sensitivity of the patientcollected specimens was 100% (95% CI, 72%-100%), and the specificity was 95% (95% CI, 74%-100%). with a positive result for the self-collected nasal sample but negative results from both physiciancollected samples. c Participant 27 was asymptomatic but had been exposed to sudden acute respiratory syndrome coronavirus 2 by close contact 4 days before the study swab was obtained.