Proper use of noncontact infrared thermometry for temperature screening during COVID-19

Abstract

Among the myriad of challenges healthcare institutions face in dealing with coronavirus disease 2019 (COVID–19), screening for the detection of febrile persons entering facilities remains problematic, particularly when paired with CDC and WHO spatial distancing guidance. Aggressive source control measures during the outbreak of COVID-19 has led to re-purposed use of noncontact infrared thermometry (NCIT) for temperature screening. This study was commissioned to establish the efficacy of this technology for temperature screening by healthcare facilities. We conducted a prospective, observational, single-center study in a level II trauma center at the onset of the COVID-19 outbreak to assess (i) method agreement between NCIT and temporal artery reference temperature, (ii) diagnostic accuracy of NCIT in detecting referent temperature $$\ge 100.0\,^{\circ }{\mathrm{F}}$$ ≥ 100.0 ∘ F and ensuing test sensitivity and specificity and (iii) technical limitations of this technology. Of 51 healthy, non-febrile, healthcare workers surveyed, the mean temporal artery temperature was $$98.4\,^{\circ }{\mathrm{F}}$$ 98.4 ∘ F ($$95\%$$ 95 % confidence interval (CI) = $$[98.2,98.6]\,^{\circ }{\mathrm{F}}$$ [ 98.2 , 98.6 ] ∘ F ). Mean NCIT temperatures measured from $${1}\,{\mathrm{ft}}$$ 1 ft , $${3}\,{\mathrm{ft}}$$ 3 ft , and $${6}\,{\mathrm{ft}}$$ 6 ft distances were $$92.2\,^{\circ }{\mathrm{F}}$$ 92.2 ∘ F $$(95\%\ {\text {CI}}=[91.8\ 92.67]\,^{\circ }{\mathrm{F}})$$ ( 95 % CI = [ 91.8 92.67 ] ∘ F ) , $$91.3\,^{\circ }{\mathrm{F}}$$ 91.3 ∘ F $$(95\%\ {\text {CI}}=[90.8\ 91.8]\,^{\circ }{\mathrm{F}})$$ ( 95 % CI = [ 90.8 91.8 ] ∘ F ) , and $$89.6\,^{\circ }{\mathrm{F}}$$ 89.6 ∘ F $$(95\%\ {\text {CI}}=[89.2 \ 90.1]\,^{\circ }{\mathrm{F}})$$ ( 95 % CI = [ 89.2 90.1 ] ∘ F ) , respectively. From statistical analysis, the only method in sufficient agreement with the reference standard was NCIT at $${1}\,{\mathrm{ft}}$$ 1 ft . This demonstrated that the device offset (mean temperature difference) between these methods was $$-6.15\,^{\circ }{\mathrm{F}}$$ - 6.15 ∘ F ($$95\%\ {\text {CI}}=[-6.56,-5.74]\,^{\circ }{\mathrm{F}}$$ 95 % CI = [ - 6.56 , - 5.74 ] ∘ F ) with 95% of measurement differences within $$-8.99\,^{\circ }{\mathrm{F}}$$ - 8.99 ∘ F ($$95\%\ {\text {CI}}=[-9.69,-8.29]\,^{\circ }{\mathrm{F}}$$ 95 % CI = [ - 9.69 , - 8.29 ] ∘ F ) and $$-3.31\,^{\circ }{\mathrm{F}}$$ - 3.31 ∘ F ($$95\%\ {\text {CI}}= [-4.00,-2.61]\,^{\circ }{\mathrm{F}}$$ 95 % CI = [ - 4.00 , - 2.61 ] ∘ F ). By setting the NCIT screening threshold to $$93.5\,^{\circ }{\mathrm{F}}$$ 93.5 ∘ F at $${1}\,{\mathrm{ft}}$$ 1 ft , we achieve diagnostic accuracy with $$70.9\%$$ 70.9 % test sensitivity and specificity for temperature detection $$\ge 100.0\,^{\circ }{\mathrm{F}}$$ ≥ 100.0 ∘ F by reference standard. In comparison, reducing this screening criterion to the lower limit of the device-specific offset, such as $$91.1\,^{\circ }{\mathrm{F}}$$ 91.1 ∘ F , produces a highly sensitive screening test at $$98.2\%$$ 98.2 % , which may be favorable in high-risk pandemic disease. For future consideration, an infrared device with a higher distance-to-spot size ratio approaching 50:1 would theoretically produce similar results at $${6}\,{\mathrm{ft}}$$ 6 ft , in accordance with CDC and WHO spatial distancing guidelines.

Evaluation of non-contact infrared thermometers for COVID-19 fever screening in healthcare workers: A prospective observational study in a tertiary care hospital

“…These differences underscore the importance of considering multiple factors when assessing NCIT efficacy for fever screening in diverse healthcare settings. [15]…”

“…These differences underscore the importance of considering multiple factors when assessing NCIT efficacy for fever screening in diverse healthcare settings. [15] In contrast, Fan Lai and colleagues emphasized the inadequacy of single NCIT measurements for fever screening, advocating triple neck measurements as the standard, and highlighted NCIT accuracy decline below 18°C due to environmental conditions. This comprehensive approach, addressing temperature variations, enhances our comprehension of NCIT intricacies and limitations.…”

The temperature difference method for screening patients with COVID-19 fever symptoms

“…In the wake of COVID-19, thermal screening has been widely implemented all over the world (v) Faster than traditional temperature measurement. IR thermometry has been applied for mass fever screening (e.g., in the airports) widely, With a number of controversial outcomes Several factors can affect fever's detection by infrared thermal devices [7].Thermal imaging cameras measure the amount of infrared energy that is sent out by face of an object; it is not a direct measure of core body temperature and can be affected by physiological factors and environmental conditions [8]. Environmental factors like absolute temperature, fluctuation in the temperature, relative humidity, etc.…”

Sensitive thermochromic behavior of InSeI, a highly anisotropic and tubular 1D van der Waals Crystal

“…More practically, the ability to measure precise temperature changes has become an integral aspect of several fields relevant to human life, such as pasteurization for food preparation, quality control for manufacturing, diagnostics for healthcare, efficiency optimization for transportation, and environmental monitoring for climate change research. [1][2][3][4][5][6] Among the recent developments in the precise determination of temperature, [7] optical thermometric platforms that are based on the temperaturedependent frequency of the spectral properties of a material to determine temperature are the most promising alternatives to sensitivity-, stability-, size-, and resolution-limited resistance thermometry. [7,8] The advantage of these optical platforms originates from their intrinsic robustness with respect to electromagnetic interference, remote readout, and high sensitivity of optical measurements.…”