Performance of Temporal Artery Temperature Measurement in Ruling Out Fever: Implications for COVID-19 Screening
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J Gen Intern Med DOI: 10.1007/s11606-020-06205-2 © Society of General Internal Medicine 2020
INTRODUCTION
Current CDC recommendations for mitigation of community COVID-19 transmission include temperature screening.1 Due to low cost and ease-of-use, temporal artery thermometers (TATs) applied to the forehead are widely employed to screen for fever, but prior literature has suggested poor sensitivity and high variability.2, 3 Published data are largely limited by small per-study sample sizes and a focus on pediatric, surgical, and intensive care settings that are not generalizable to real-world screening populations. We sought to determine the real-world test performance of TATs for fever rule-out by utilizing a large electronic dataset of emergency department encounters for whom universal temperature screening was conducted. For reference standards, we included rectal temperature, a widely recognized core temperature, as well as oral temperature, which benefits from wide clinical acceptance and robust specificity.2 Our primary objective was to determine TAT sensitivities and specificities across a range of temperatures in comparison with rectal and oral cutoffs of 100.4 °F/38 °C. Our secondary outcome was limit-ofagreement (LOA) by Bland-Altman analysis.
METHODS
We extracted temperature measurements and method of temperature assessment from electronic health record (EHR) data (Epic, Verona, WI) collected between March 2013 and June 2019 within a large hospital system comprising ten acute care sites. We identified paired perpatient data where a TAT measurement was documented within 15 minutes of a rectal temperature measurement or oral temperature. When multiple measurements were taken with a single modality within the defined interval, the mean value was used. In the Bland-Altman analysis, we Received June 19, 2020 Accepted August 31, 2020
calculate the mean of the differences between the paired measurements and the limits-of-agreement (LOA) as defined by 95% confidence interval bounds.
RESULTS
We identified 1.84 million adult (age > 18 years) emergency department visits by 602,089 patients with over 4.6 million temperature readings; there were 1293 paired readings from 1276 encounters that met our inclusion for TAT versus rectal measurement and 16,132 readings from 16,031 encounters for TAT versus oral measurement. The admission rate across the paired measurement patient population was 50.0%. The prevalence of fever in the rectal and oral temperature populations was 34.4% and 4.3%, respectively. Using a threshold of 100.4 °F, TAT measurement identified fever compared with the rectal reference with sensitivity 0.27 (95% CI 0.27–0.31), specificity 0.98 (0.96–0.99), PPV 0.85 (0.79–0.91), and NPV 0.72 (0.69–0.74). TAT measurement identified fever compared with the oral reference with a sensitivity 0.23 (95% CI 0.20–0.26), specificity 0.99 (0.99–0.99), PPV 0.53 (0.48– 0.59), and NPV 0.97 (0.96–0.97). We did not observe significant differences in fever sensitivity when limiting our paired analysis to 5- or 10-minu
