OBJECTIVES: Hidradenitis suppurativa (HS) patients experience a significant delay to diagnosis. This study investigates relationships between effect modifiers and diagnostic delay from the perspective of healthcare system equity.

METHODS: A targeted literature review identified and summarised published factors associated with delayed HS diagnosis including healthcare disparities to inform data analysis. In addition, Adelphi 2020/21 HS Disease Specific Programme (DSP™), a real-world point-in-time survey of dermatologists and their consulting patients in Europe and the US, were used in a univariate Cox proportional hazards model regarding time from patient first experience of HS symptoms to receiving a HS diagnosis, to explore demographic and circumstantial factors contributing to this delay.

RESULTS: 25 key publications were identified from 394 records that directly determined reasons for delayed HS diagnosis. Factors with high importance included ethnicity, smoking status, employment, gender, obesity, body-mass index (BMI), family history, age of HS onset, delay in specialist referral, misdiagnoses, and patient embarrassment. However, based on the Joanna Briggs Institute critical appraisal checklist and additional criterions like publication type, sample size etc., much of the evidence was of lower quality but matched the findings of the DSP analysis.

In total, 424 patients from the DSP were eligible for data analysis. Factors contributing to diagnostic delay included BMI, age at symptom onset, country, ethnicity, previous misdiagnoses, family history, smoking status, draining tunnels or scarring at diagnosis, current itching and genitals or thighs affected (all p-values ≤ 0.05).

CONCLUSIONS: Both literature and DSP analysis found, effect modifiers of high importance included BMI, age of HS onset, smoking status, gender, ethnicity, and misdiagnoses. However, the relative impact of specific effect modifiers revealed in the DSP, such as ethnicity, do not match the quality of existing published evidence. Further research is required to enrich these results and investigate the individual contribution of each effect modifier.