The 'Buruli Score': Development of a Multivariable Prediction Model for Diagnosis of Mycobacterium ulcerans Infection in Individuals with Ulcerative Skin Lesions, Akonolinga, Cameroon

Background Access to laboratory diagnosis can be a challenge for individuals suspected of Buruli Ulcer (BU). Our objective was to develop a clinical score to assist clinicians working in resource-limited settings for BU diagnosis. Methododology/Principal Findings Between 2011 and 2013, individuals presenting at Akonolinga District Hospital, Cameroon, were enrolled consecutively. Clinical data were collected prospectively. Based on a latent class model using laboratory test results (ZN, PCR, culture), patients were categorized into high, or low BU likelihood. Variables associated with a high BU likelihood in a multivariate logistic model were included in the Buruli score. Score cut-offs were chosen based on calculated predictive values. Of 325 patients with an ulcerative lesion, 51 (15.7%) had a high BU likelihood. The variables identified for the Buruli score were: characteristic smell (+3 points), yellow color (+2), female gender (+2), undermining (+1), green color (+1), lesion hyposensitivity (+1), pain at rest (-1), size >5cm (-1), locoregional adenopathy (-2), age above 20 up to 40 years (-3), or above 40 (-5). This score had AUC of 0.86 (95%CI 0.82–0.89), indicating good discrimination between infected and non-infected individuals. The cut-off to reasonably exclude BU was set at scores
Author Summary In most Buruli ulcer (BU) endemic areas, laboratory diagnosis is hard to access and comes at a high cost. Clinicians are in need of new tools to assist them in identifying which patients truly require additional work-up and which can be treated directly. We analyzed the clinical data of all patients with ulcerative skin lesions that presented to Akonolinga District Hospital in Cameroon and identified which parameters were associated with BU diagnosis. We attributed a certain number of points to each parameter to build a “Buruli score”. Based on score results, clinicians can be advised either to directly treat BU (score ≥4), to look for another diagnosis (score