Clinical Diagnosis is Highly Predictive of Laboratory-Confirmed Mpox in a Sexual Health Clinic

Abstract

Abstract Background Promptly recognizing mpox can facilitate earlier diagnosis and appropriate treatment. How accurately clinicians can diagnose mpox based on clinical data and before receiving molecular test results is not known. Methods Leveraging public health and clinical data collected in Seattle-King County’s Sexual Health Clinic (SHC) from 7/29/22 to 9/30/22, we analyzed the proportion of patients who received presumptive vs results-based tecovirimat when clinicians had a high, intermediate or low suspicion for mpox after clinical evaluation. We calculated the sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of this approach against gold standard mpox polymerase chain reaction (PCR) results. Results Of 321 patients evaluated for mpox in the SHC, median age was 34.5 years and 88% were cisgender men. Overall, 121 (38%) of 319 tested positive by mpox PCR. Clinicians had high suspicion for mpox in 122 patients and offered empiric tecovirimat to 92 (88%), of whom 85 (92%) tested PCR positive. Of 13 intermediate suspicion patients offered presumptive therapy, all accepted but none tested positive by PCR. The sensitivity, specificity, PPV and NPV of high/intermediate clinical suspicion for mpox were 99%, 90%, 86% and 99%, respectively. A higher proportion of people with HIV were diagnosed with mpox (57% vs 36%, P = 0.01, chi-square test), and sensitivity and PPV of high/intermediate clinical suspicion in this subgroup were 100% and 86%, respectively. Conclusions Clinical providers working in a high-volume, public SHC were able to both accurately identify and rule out mpox based on clinical examination prior to receiving PCR test results.