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Handheld infrared thermometer to evaluate cellulitis: the HI-TEC study
Koray K Demir1, Emily G McDonald2, Samuel de L'Étoile-Morel3
1Department of Medicine, McGill University, Montréal, QC, Canada.
Insights
A handheld infrared thermometer can help distinguish cellulitis from pseudocellulitis, reducing unnecessary antibiotic use. A temperature difference of 0.8°C or more between limbs effectively aids in diagnosing cellulitis.
Area of Science:
- Medical diagnostics
- Infectious diseases
- Dermatology
Background:
- Differentiating cellulitis from pseudocellulitis is clinically challenging.
- Misdiagnosis leads to increased antimicrobial use and healthcare costs.
- Current diagnostic standards rely on clinical assessment, sometimes requiring expert consultation.
Purpose of the Study:
- To evaluate the utility of a handheld infrared thermometer in improving diagnostic certainty for suspected cellulitis.
- To determine the optimal temperature difference threshold for differentiating cellulitis from pseudocellulitis.
Main Methods:
- A cross-sectional study involving adult patients with suspected limb cellulitis was conducted.
- Infrared thermometry compared affected limb temperature to the contralateral limb.
- Youden's method identified the optimal temperature difference threshold for diagnosis.
Main Results:
- The mean temperature difference was 2.6°C in cellulitis patients versus 0.4°C in non-cellulitis patients (p < 0.001).
- A temperature difference of ≥0.8°C demonstrated 95% sensitivity and 69% specificity for cellulitis.
- The area under the receiver operating curve (c-statistic) was 0.82.
Conclusions:
- A handheld infrared thermometer serves as a valuable tool in differentiating cellulitis from pseudocellulitis.
- This non-invasive method can potentially improve diagnostic accuracy in clinical settings.
- Further validation in larger, multi-center studies is warranted.
Objectives:
Differentiating cellulitis from pseudocellulitis is challenging, and misdiagnosis leads to unnecessary antimicrobial use and increased healthcare expenditure. Clinical diagnosis remains the criterion standard and may involve expert consultation. Our objective was to evaluate the usefulness of a handheld infrared thermometer to improve diagnostic certainty in cases of suspected cellulitis.
Methods:
We conducted a cross-sectional study from August 2018 to January 2020 at a tertiary-care hospital in Montreal, Canada. We enrolled adult patients with suspected limb cellulitis. Using the infrared thermometer, we compared the average temperature of the affected area with that of the contralateral limb, and we used Youden's method to determine the optimal temperature difference which best differentiated cellulitis from pseudocellulitis as determined by an independent and blinded infectious diseases specialist. We used bootstrapping to estimate 95% confidence intervals for the sensitivity, specificity, and area under the receiver operating curve.
Results:
Of 65 patients screened for enrolment, 52 patients were recruited (median age: 64 years, IQR 52-76); 39 of these were diagnosed with cellulitis and 13 were not. The mean temperature difference between affected and unaffected limbs was 2.6°C (95%CI 2.1-3.1°C) for patients with cellulitis and 0.4°C (95%CI -1.2°C to 2.1°C) for patients without (p < 0.001). An average temperature difference between limbs of 0.8°C or more was 95% sensitive (95%CI 74-100%) and 69% specific (95%CI 44-95%) for the diagnosis of cellulitis (c-statistic 0.82).
Conclusions:
In this proof-of-concept single-centre study, a handheld infrared thermometer was a useful aid to differentiate cellulitis from pseudocellulitis.
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