Inter-rater reliability and prospective validation of a clinical prediction rule for SARS-CoV-2 infection.

OBJECTIVES: Accurate estimation of the risk of SARS-CoV-2 infection based on bedside data alone has importance to emergency department (ED) operations and throughput. The 13-item CORC (COVID [or coronavirus] Rule-out Criteria) rule had good overall diagnostic accuracy in retrospective derivation and validation. The objective of this study was to prospectively test the inter-rater reliability and diagnostic accuracy of the CORC score and rule (score ≤ 0 negative, > 0 positive) and compare the CORC rule performance with physician gestalt. METHODS: This noninterventional study was conducted at an urban academic ED from February 2021 to March 2021. Two practitioners were approached by research coordinators and asked to independently complete a form capturing the CORC criteria for their shared patient and their gestalt binary prediction of the SARS-CoV-2 test result and confidence (0%-100%). The criterion standard for SARS-CoV-2 was from reverse transcriptase polymerase chain reaction performed on a nasopharyngeal swab. The primary analysis was from weighted Cohen's kappa and likelihood ratios (LRs). RESULTS: For 928 patients, agreement between observers was good for the total CORC score, κ = 0.613 (95% confidence interval [CI] = 0.579-0.646), and for the CORC rule, κ = 0.644 (95% CI = 0.591-0.697). The agreement for clinician gestalt binary determination of SARs-CoV-2 status was κ = 0.534 (95% CI = 0.437-0.632) with median confidence of 76% (first-third quartile = 66-88.5). For 425 patients who had the criterion standard, a negative CORC rule (both observers scored CORC < 0), the sensitivity was 88%, and specificity was 51%, with a negative LR (LR-) of 0.24 (95% CI = 0.10-0.50). Among patients with a mean CORC score of >4, the prevalence of a positive SARS-CoV-2 test was 58% (95% CI = 28%-85%) and positive LR was 13.1 (95% CI = 4.5-37.2). Clinician gestalt demonstrated a sensitivity of 51% and specificity of 86% with a LR- of 0.57 (95% CI = 0.39-0.74). CONCLUSION: In this prospective study, the CORC score and rule demonstrated good inter-rater reliability and reproducible diagnostic accuracy for estimating the pretest probability of SARs-CoV-2 infection.

Optical stimulation of the facial nerve: a new monitoring technique?

OBJECTIVES/ HYPOTHESIS: One sequela of skull base surgery is iatrogenic damage to cranial nerves, which can be prevented if the nerve is identified. Devices that stimulate nerves with electric current assist in nerve identification. Contemporary devices have two main limitations: 1) the physical contact of the stimulating electrode and (2) the spread of the current through the tissue. In contrast to electrical stimulation, pulsed infrared optical radiation can be used to safely and selectively stimulate neural tissue and might be valuable for screening. METHODS: The gerbil facial nerve was exposed to 250 microsecond pulses of 2.12 microm radiation delivered via a 600-microm-diameter optical fiber at a repetition rate of 2 Hz. With use of 27 GA, 12-mm intradermal electrodes, muscle action potentials were recorded. Nerve samples were examined for possible tissue damage. RESULTS: Eight facial nerves were stimulated with radiant exposures between 0.71 and 1.77 J/cm, resulting in compound muscle action potentials (CmAPs) that were simultaneously measured at the m. orbicularis oculi, m. levator nasolabialis, and m. orbicularis oris. Resulting CmAP amplitudes were 0.3 to 0.4 mV, 0.15 to 1.4 mV, and 0.3 to 2.3 mV, respectively, depending on the radial location of the optical fiber and the radiant exposure. Individual nerve branches were also stimulated, resulting in CmAP amplitudes between 0.2 and 1.6 mV. Histology revealed tissue damage at radiant exposures of 2.2 J/cm but no apparent damage at radiant exposures of 2.0 J/cm. CONCLUSIONS: The experiments showed that selective muscle action potentials can be evoked optically in the gerbil facial nerve without direct physical contact.