Evaluating the diagnostic accuracy of a screening questionnaire for detecting hidradenitis suppurativa: a pooled analysis of accuracy measures from the Global Hidradenitis Suppurativa Atlas (GHiSA) study

BACKGROUND: Hidradenitis suppurativa (HS) is an inflammatory skin condition that is associated with a prolonged diagnostic delay of approximately 7-10 years. The diagnostic delay can be attributed to various factors, including low awareness of diagnostic criteria among nondermatological healthcare professionals often leading to misdiagnosis. Screening questionnaires have been proposed for the diagnosis of HS. One such questionnaire has been validated and used in the Global Hidradenitis Suppurativa Atlas (GHiSA) Global Prevalence Study (GPS). OBJECTIVES: To evaluate and provide a summary of the diagnostic accuracy measures (pooled sensitivity and specificity) of the screening questionnaire employed in the GHiSA GPS. METHODS: All studies that adhered to the methodology specified by the GHiSA and provided diagnostic accuracy data were eligible for inclusion. Data on geographical location and diagnostic accuracy parameters (true positive, false positive, true negative and false negative) were extracted from the included studies and entered in duplicate into Microsoft Excel independently by two authors. The quality of the studies was assessed using the quality assessment of diagnostic accuracy studies (QUADAS-2) tool. RESULTS: Data from 25 studies carried out in 23 countries were included in the pooled analysis. The QUADAS-2 assessment revealed a high risk of bias in the domains 'reference standard' and 'patient flow'. For the applicability of the studies, there were concerns about 'patient selection'. Substantial variations in sensitivity (0.43-1.00) and specificity (0.15-1.00) values were observed globally. A bivariate random effects model showed a pooled sensitivity of 0.88 [95% confidence interval (CI) 0.80-0.94] and a pooled specificity of 0.86 (95% CI 0.78-0.91). The summary receiver operating curve revealed a clustering of studies in the upper left corner, indicating a sensitivity and specificity close to 1. The area under the curve was 0.93, suggesting excellent accuracy. CONCLUSIONS: Despite substantial variations in diagnostic estimates around the world, the pooled analysis indicated that the accuracy of the GHiSA screening questionnaire was excellent. The screening questionnaire may prove useful for triage, ensuring that only individuals fitting the criteria for HS see specialized dermatological care.