Biologic Treatment for Hidradenitis Suppurativa

Kelsey S. Flood; Martina L. Porter; Alexa B. Kimball

Disclosures

Am J Clin Dermatol. 2019;20(5):625-638. 

In This Article

Hidradenitis Suppurativa Scoring Systems

Prior to discussing the research supporting efficacy of biologics in HS, it is important to understand how HS severity is assessed and monitored in clinical trials. Various scoring systems have been used in HS clinical trials. Hurley staging was originally developed in 1989 with the intent of guiding treatment options.[5] Hurley staging is a three-stage system in which the different stages are defined by the presence or absence of draining tracts, scarring, and normal intervening skin.[6,7] Critiques of the Hurley staging system include the fact that it does not account for inflammation nor does it incorporate the number of anatomical sites involved.[6,7] While Hurley staging remains useful in clinical practice, its use in clinical trials is limited as it is a static scoring system. Impetus among researchers to develop an outcome measurement that accurately captured dynamic response to treatment for use in clinical trials therefore led to the development of several additional scoring systems.

The modified Sartorius score (mSS) is a weighted scoring system that accounts for the number of regions involved, types of lesion involved, distance between involved lesions, and presence or absence of intervening normal skin.[8] However, a limitation of mSS is that the score requires detailed counting of lesions and measuring in between lesions, which can be time consuming.[9] The Hidradenitis Suppurativa Severity Index (HSSI) is another early scoring system that is determined by the number of involved sites, percent body surface area affected by HS, number of lesions, number of dressing changes, and pain as measured by a visual analog scale (VAS).[10]

The Hidradenitis Suppurativa Physician's Global Assessment (HS PGA) was developed thereafter in anticipation of larger clinical trials in HS. HS PGA is an ordinal scale that categorizes patients into one of six categories, clear, minimal, mild, moderate, severe, or very severe. In a phase II clinical trial, clinical response, as measured by HS PGA, was defined as having a score of either clear, minimal, or mild and a concurrent 2-grade improvement in score compared with baseline score.[11] One critique of HS PGA is that it may be too rigid a scoring system.[12] Hidradenitis Suppurativa Clinical Response (HiSCR), which was developed after HS PGA using data from a clinical trial data set, is a binary scale defined as a reduction of at least 50% in the total abscess and inflammatory nodule count with no increase in both the abscess count and the draining fistula count relative to baseline.[12] It has been validated by both patient- and physician-reported outcomes.[9] A recent observational study demonstrated that HiSCR has acceptable inter- and intra-rater reliability, further supporting its use as a scoring tool in clinical trials.[13]

The European Hidradenitis Suppurativa Foundation (EHSF) recently developed a dynamic scoring tool called the International Hidradenitis Suppurativa Severity Score System (IHS4), which is calculated by assigning weighted points to the number of nodules, abscesses, and draining tunnels. This scoring system has also been validated by patient- and physician-reported outcomes.[14] Another recently developed scoring tool is the Acne Inversa Severity Index (AISI). AISI is a scoring system where individual lesions are given weighted points that are then multiplied by the number of sites at which these lesions are found.[10,15] However, to our knowledge AISI has not been implemented in any clinical trials to date. Lastly, some studies have assessed HS by the disease activity score, which is calculated by measuring the affected areas and multiplying that by the degree of inflammation at each site, and then summing the scores of all affected areas.[16,17]

There are many scoring systems in place; at present, none comprehensively capture all dimensions and presentations of HS. Importantly, no scoring system takes into effect duration of disease or the underlying etiology of the disease. For example, there is no accounting for whether a patient has an underlying genetic defect or more hormonally driven presentation. Further, as evidenced by the number of scoring systems in use, another challenge in studying the efficacy of biologic therapies in HS has been the development of a scoring system that is well validated and universally adopted. The multiple scoring systems invoked in clinical trials for HS are prohibitive to comparing results between clinical trials and also to the ability of researchers to perform meta-analyses.

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