Application of an Interactive Diagnosis Ranking Algorithm in a Simulated Vignette-based Environment for General Dermatology.

Introduction: Diagnostic algorithms may reduce noise and bias and improve interrater agreement of clinical decisions. In a practical sense, algorithms may serve as alternatives to specialist consultations or decision support in store-and-forward tele-dermatology. It is, however, unknown how dermatologists interact with algorithms based on questionnaires. Objectives: To evaluate the performance of a questionnaire-based diagnostic algorithm when applied by users with different expertise. Methods: We created 58 virtual test cases covering common dermatologic diseases and asked five raters with different expertise to complete a predefined clinical questionnaire, which served as input for a disease ranking algorithm. We compared the ranks of the correct diagnosis between users, analyzed the similarity between inputs of different users, and explored the impact of different parts of the questionnaire on the final ranking. Results: When applied by a board-certified dermatologist, the algorithm top-ranked the correct diagnosis in the majority of cases (median rank 1; interquartile range: 1.0; mean reciprocal rank 0.757). The median rank of the correct diagnosis was significantly lower when the algorithm was applied by four dermatology residents (median rank 2-5, P < 0.01). The lowest similarity between inputs of the residents and the board-certified dermatologist was found for questions regarding morphology. Sensitivity analysis showed the highest deterioration in performance after omission of information on morphology and anatomic site. Conclusions: A simple questionnaire-based disease ranking algorithm provides accurate ranking for a wide variety of dermatologic conditions. When applied in clinical practice, additional measures may be needed to ensure robustness of data entry for inexperienced users.

Prevalence of Skin-specific Autoantibodies in HIV-infected Patients and Uninfected Controls.

Various autoantibodies are detected more frequently in HIV-infected individuals than in HIV-negative controls; however, limited data exist regarding autoimmune blistering skin diseases. Using enzyme-linked immunoassay (ELISA) and indirect immunofluore-scence, no difference in the frequency and magnitude of autoantibodies against BP180, BP230, desmoglein 1 and 3 was found between 594 HIV-infected patients and 248 uninfected controls in this cross-sectional study (16.0% vs. 11.7%, respectively, for at least one positive ELISA, p = 0.11). Interestingly, reactive syphilis serology in both HIV-infected individuals and uninfected controls was associated with positive anti-BP180 ELISA results (adjusted odds ratio (OR) 2.14, 95% confidence interval (CI) 1.07-4.29, p = 0.03 and OR 4.70, CI 1.3-16.86; p = 0.0180). Our study shows a comparably low prevalence of cutaneous autoantibodies in both HIV-infected patients and uninfected controls lacking signs of autoimmune blistering skin disease. Positive BP180 ELISA in the absence of clinical signs of bullous pemphigoid should prompt further evaluation for syphilis antibodies.