Validation of Thermal Imaging and the ALT-70 Prediction Model to Differentiate Cellulitis From Pseudocellulitis.

Importance: Cellulitis is misdiagnosed in up to 30% of cases due to mimic conditions termed pseudocellulitis. The resulting overuse of antibiotics is a threat to patient safety and public health. Surface thermal imaging and the ALT-70 (asymmetry, leukocytosis, tachycardia, and age ≥70 years) prediction model have been proposed as tools to help differentiate cellulitis from pseudocellulitis. Objectives: To validate differences in skin surface temperatures between patients with cellulitis and patients with pseudocellulitis, assess the optimal temperature measure and cut point for differentiating cellulitis from pseudocellulitis, and compare the performance of skin surface temperature and the ALT-70 prediction model in differentiating cellulitis from pseudocellulitis. Design, Setting, and Participants: This prospective diagnostic validation study was conducted among patients who presented to the emergency department with acute dermatologic lower extremity symptoms from October 11, 2018, through March 11, 2020. Statistical analysis was performed from July 2020 to March 2021 with additional work conducted in September 2023. Main Outcomes and Measures: Temperature measures for affected and unaffected skin were obtained. Cellulitis vs pseudocellulitis was assessed by a 6-physician, independent consensus review. Differences in temperature measures were compared using the t test. Logistic regression was used to identify the temperature measure and associated cut point with the optimal performance for discriminating between cellulitis and pseudocellulitis. Diagnostic performance characteristics for the ALT-70 prediction model, surface skin temperature, and both combined were also assessed. Results: The final sample included 204 participants (mean [SD] age, 56.6 [16.5] years; 121 men [59.3%]), 92 (45.1%) of whom had a consensus diagnosis of cellulitis. There were statistically significant differences in all skin surface temperature measures (mean temperature, maximum temperature, and gradients) between cellulitis and pseudocellulitis. The maximum temperature of the affected limb for patients with cellulitis was 33.2 °C compared with 31.2 °C for those with pseudocellulitis (difference, 2.0 °C [95% CI, 1.3-2.7 °C]; P < .001). The maximum temperature was the optimal temperature measure with a cut point of 31.2 °C in the affected skin, yielding a mean (SD) negative predictive value of 93.5% (4.7%) and a sensitivity of 96.8% (2.3%). The sensitivity of all 3 measures remained above 90%, while specificity varied considerably (ALT-70, 22.0% [95% CI, 15.8%-28.1%]; maximum temperature of the affected limb, 38.4% [95% CI, 31.7%-45.1%]; combination measure, 53.9% [95% CI, 46.5%-61.2%]). Conclusions and Relevance: In this large diagnostic validation study, significant differences in skin surface temperature measures were observed between cases of cellulitis and cases of pseudocellulitis. Thermal imaging and the ALT-70 both demonstrated high sensitivity, but specificity was improved by combining the 2 measures. These findings support the potential of thermal imaging, alone or in combination with the ALT-70 prediction model, as a diagnostic adjunct that may reduce overdiagnosis of cellulitis.

Patients' willingness to accept adverse event and cost tradeoffs from oral nicotinamide for reduced risk of non-melanoma skin cancer.

BACKGROUND: Non-immunosuppressed patients with a history of multiple non-melanoma skin cancers (NMSCs) taking oral nicotinamide supplementation experienced a 23% decrease in annual NMSC risk in a randomized clinical trial. Patient preferences for risks and costs associated with nicotinamide are unknown. OBJECTIVES: To understand how patients prioritize NMSC reduction, infection risk, and cost. METHODS: A sample of adults with history of ≥2 NMSC within the past five years undergoing Mohs procedure completed a discrete-choice experiment comprising two hypothetical treatments-characterized by varying reductions in NMSC incidence, increased severe infection risk, and cost-and no treatment. The data were analyzed with random-parameters logit models. RESULTS: A total of 203 subjects (mean age 71.5 years, 65.5% males) participated. For a 23% annual reduction in NMSC incidence, a 26% [95% CI: 8%-45%] annual increase in severe infection risk and $8 [95% CI: $2-14] monthly cost was acceptable. Outcomes across analyzed subgroups (before vs. during COVID pandemic, site of interview, less vs. more prior NMSCs) were similar. CONCLUSIONS: Patients were unwilling to accept high severe infection risks to obtain the reduction in NMSC incidence observed in a nicotinamide trial, suggesting that routinely recommending nicotinamide may run counter to some patients' preferences.

Comparing skin surface temperature to clinical documentation of skin warmth in emergency department patients diagnosed with cellulitis.

Objective: To compare clinical documentation of skin warmth to patient report and quantitative skin surface temperatures of patients diagnosed with cellulitis in the emergency department (ED). Methods: Adult patients (≥18 years) presenting to the ED with an acute complaint involving visible erythema of the lower extremity were prospectively enrolled. Those diagnosed with cellulitis were included in this analysis. Participant report of skin warmth was recorded and skin surface temperature values were obtained from the affected and corresponding unaffected area of skin using thermal cameras. Average temperature (Tavg) was extracted from each image and the difference in Tavg between the affected and unaffected limb was calculated (Tgradient). Clinical documentation of skin warmth was compared to patient report and measured skin warmth (Tgradient >0°C). Results: Among 126 participants diagnosed with cellulitis, 110 (87%) exhibited objective warmth (Tgradient >0°C) and 58 (53%) of these cases had warmth documented in the physical examination. Of those with objective warmth, 86 (78%) self-reported warmth and 7 (6%) had warmth documented in their history of present illness (HPI) (difference = 72%, 95% confidence interval [CI]: 62%-82%; P < 0.001). A significant difference was observed for Tavg affected when warmth was documented (32.1°C) versus not documented (31.0°C) in the physical examination (difference = 1.1°C, 95% CI: 0.29-1.94; P = 0.0083). No association was found between Tgradient and patient-reported or HPI-documented warmth. Conclusions: The majority of ED-diagnosed cellulitis exhibited objective warmth, yet significant discordance was observed between patient-reported, clinician-documented, and measured warmth. This raises concerns over inadequate documentation practices and/or the poor sensitivity of touch as a reliable means to assess skin surface temperature. Introduction of objective temperature measurement tools could reduce subjectivity in the assessment of warmth in patients with suspected cellulitis.

Calcitriol 3 microg/g ointment in the management of mild to moderate plaque type psoriasis: results from 2 placebo-controlled, multicenter, randomized double-blind, clinical studies.

BACKGROUND: Psoriasis is a chronic skin disorder affecting approximately 2% of the US population. Psoriasis may occur anywhere on the body with initial presentation usually seen between 15 and 30 years of age. Calcitriol 3 microg/g ointment has demonstrated good clinical efficacy as well as topical and systemic safety when used to treat psoriasis. OBJECTIVES: To confirm the efficacy and safety of calcitriol 3 microg/g ointment versus its vehicle in the treatment of subjects with mild to moderate chronic plaque psoriasis. METHODS: Suitable subjects were randomized to receive either calcitriol 3 microg/g ointment or its vehicle twice daily for up to 8 weeks in 2 multicenter, randomized, vehicle-controlled, double-blind parallel group studies. Efficacy was evaluated through a Global Severity Score dichotomized in success (clear and minimal) or failure. Erythema, plaque elevation, scaling and dermatologic sum score (sum of the scores for erythema, plaque elevation, and scaling), pruritus, and global improvement were also assessed. Routine safety and clinical laboratory parameters, including calcium homeostasis, were evaluated throughout the study. RESULTS: In total, 839 subjects were included in the 2 studies: 419 patients received calcitriol 3 microg/g ointment and 420 received the vehicle. In both studies, calcitriol 3 microg/g ointment was shown to be significantly more effective than its vehicle, with onset of therapeutic effect seen as early as week 2 and sustained at all subsequent visits. Calcitriol 3 microg/g ointment demonstrated good systemic and local safety profile comparable to its vehicle with no effect on calcium homeostasis. CONCLUSION: Calcitriol 3 microg/g ointment applied for 8 weeks is effective and safe in the treatment of mild to moderate psoriasis.