AISI: A New Disease Severity Assessment Tool for Hidradenitis Suppurativa

Introduction. Hidradenitis suppurativa (HS) is a chronic, disabling, skin disorder. Because of renewed scientific interest in HS, different aspects of the condition, such as disease severity assessment, are being investigated and better defined. The aim of this study is to provide a novel tool for the assessment of disease severity. Methods and Materials. An HS-tailored, composite, dynamic score, named the Acne Inversa Severity Index (AISI) was designed to include a physician-rated assessment that considers the type of lesions occurring and the affected body sites. Additionally, a 0-10 visual analog scale (VAS), named Illness-VAS, was created to assess a patient’s pain, discomfort, and disability due to HS. The authors compared AISI with other validated measurements, namely the Hurley staging classification, modified Sartorius score, and the Dermatology Life Quality Index (DLQI). Results. The AISI was tested in 46 patients with HS, demonstrating a significant correlation with Hurley staging (r: 0.70856; P = 0.0021), modified Sartorius score (r: 0.9730; P = <0.00001), and DLQI (r: 0.8257; P = 0.0221). According to AISI cut-offs, HS may be defined as mild (AISI < 10), moderate (AISI 10 > 18), and severe (AISI > 18). Additionally, comparing the 2 dynamic scores, AISI and Sartorius, AISI proved significantly faster than the Sartorius score (46.44 ± 19.24 seconds vs 83.2 ± 19.04 seconds; P =1.31 x 10-6). Conclusions. Being simple, fast, dynamic, and accurate, the AISI could represent the ideal measurement for HS severity in both real-life and clinical trial settings.

Hidradenitis suppurativa (HS) is a chronic, recurrent, disabling inflammatory skin disease, clinically characterized by painful, deep, inflamed nodules progressing to abscesses, sinus tracts, and scarring.¹ The open wounds heal slowly and their management is particularly challenging. It was erroneously considered a rare disease as epidemiologic studies showed a prevalence of up to 4%.² It usually affects young subjects (postpuberty age) and, more frequently, it is observed in women, with a 3:1 ratio.³ Typically, HS lesions are localized in apocrine gland-bearing regions including the axillae, groin, ano-genital region, breasts (mainly in women), and buttocks, and they are associated with malodorous and staining secretions. Hidradenitis suppurativa is usually associated with depression and severe overall impairment of quality of life (QoL), exceeding other skin disorders heavily impacting QoL such as psoriasis, atopic dermatitis, alopecia, and acne.^3-5 Hidradenitis suppurativa may restrict simple movements, interfere with routine daily activities, be disfiguring because of the wound healing and scarring process, and limit the ability to work.

Pain is reported as the most significant factor contributing to the impairment of QoL in patients with HS, although malodorous and staining secretions also contribute to poor self-perception, embarrassment, stunted social life, and problems with interpersonal relationships. A plethora of comorbidities including inflammatory bowel diseases, spondyloarthropathies, obesity, and metabolic syndrome, may be associated with HS, increasing the disease burden.⁶ Therefore, the availability of disease severity assessment tools that might accurately evaluate both clinical picture and patients’ discomfort is important for the management of patients with HS and for driving the therapeutic strategy. There are multiple assessment tools or questionnaires used for evaluating HS severity. Some are specifically designed for HS, such as the Hurley staging classification, the modified Sartorius score, the Hidradenitis Suppurativa Clinical Response (HiSCR), the Hidradenitis Suppurativa-Physician Global Assessment (HS-PGA), and the Hidradenitis Suppurativa Severity Index (HSSI), whereas others, including the Dermatology Quality of Life Index (DLQI), the SF-36 short-form health survey, and the Skindex, are not HS-specific. The Hurley staging and the modified Sartorius score are the most commonly used assessment tools in both trial setting and real-life practice.

Despite the large number of evaluating tools that have been proposed, no gold standard assessment tool has been identified. The available clinical measures might not have optimal sensitivity, may have poor ease of use, or be strictly related to the assessment of the clinical response. Therefore, the authors sought to design a dynamic, combined, assessment tool, the Acne Inversa Severity Index (AISI), that could be easily used in both clinical practice and trial settings, and that could better capture disease severity.

This study was performed at the University of Rome Tor Vergata (Rome, Italy). All patients affected by HS and who were referred to the Dermatology Clinic of the Tor Vergata University Hospital from February 2014 to February 2015 were enrolled. The severity of disease was assessed by validated measuring tests including the Hurley staging classification, the modified Sartorius score, and the DLQI. Two physician-rated HS disease severity assessments, Hurley staging classification, and modified Sartorius score, were used as referring measurements. The Hurley staging classification is based on clinical HS features, and it classifies HS into 3 stages: as mild (Hurley I), moderate (Hurley II), and severe (Hurley III).⁷

The modified Sartorius score consists of 4 clinical parameters including the number of affected areas and HS lesion hallmarks. It has a minimum value of 0 and no maximum limit.⁸

Additionally, 1 patient-reported measure, the DLQI, was tested. It is a validated and widely used questionnaire for assessing QoL related to dermatology conditions. Its score constitutes the summation of responses to all 10 items, ranging from 0 (the best QoL) to 30 (worse QoL).⁹

Because this study was not aimed to either assess therapeutic response to a specific drug or to correlate any assessment score with the therapeutic strategy prescribed, data about both previous and current treatments were not reported.

Disease severity was also assessed by the AISI that was designed as combined, dynamic, HS-dedicated staging score. The AISI is a composite score defined by a physician-rated assessment, describing the presence of peculiar HS lesions corresponding to a predefined score (ie, comedonic lesion, 1 point; abscess, 2 points; sinus tract, 3 points; keloid and fibrotic adherence, 4 points; fibrosclerotic inflammatory plaque, 5 points) that is multiplied by the number of body sites where that type of lesion appears (Figure 1). Predefined scores were arbitrarily identified by the authors based on their clinical experience in managing patients with HS, similar to previously published assessment tools, wherein criteria, parameters, or scores were postulated by the authors.^7-13

The partial score obtained by the physician assessment was added to the patient-rated evaluation, assessed by a 0-10 visual analog scale (VAS) called the Illness-VAS, representing patient’s discomfort, and/or pain, and/or soreness, and/or disability. Figure 2 shows an example of performing an AISI score. Physicians were timed while performing disease severity evaluation by AISI and Sartorius. Timing was considered for the 2 dynamic scoring systems that include a calculation, whereas Hurley staging is static and represents an overall evaluation of disease severity.

Statistical analysis. Correlations with physician-rated scores (Hurley staging classification and modified Sartorius score) and patient-reported assessment (DLQI) were performed to test the measurement accuracy and consistency of AISI.

Two-tailed Pearson’s correlation test was performed to test the correlation between (AISI vs. Sartorius and AISI vs. DLQI), whereas to assess the correlation between AISI and Hurley staging, Spearman’s rank correlation coefficient test was calculated.

As previously defined, a correlation of 0.70 or higher is generally considered strong, while a coefficient, ranging from 0.4 to 0.7, identifies a moderate correlation.^14,15P values lower than 0.05 were considered statistically significant.

Overall, the authors evaluated 46 patients affected by HS (Table 1). The majority of the study population was female (29, 63.04%), with a mean age of 34.47 (SD ± 10.90) years, ranging from 17-62 years, mean disease duration of 12.7 (SD ± 9.57) years, and mean BMI of 25.77 (SD ± 5.21). About 70% of patients were current smokers (32, 69.56%), and about 17% reported a family history for HS. 

Based on Hurley staging, 18 patients (39.14%) suffered from mild HS (Hurley I), 14 patients from moderate HS (30.43%), and 14 patients (30.43%) from severe HS (Hurley III). The mean modified Sartorius score was 30.6 (SD ± 27.58), while mean DLQI value was 15 (SD ± 9.10). Testing AISI, the mean score obtained was 18.89 (SD ± 15.88), with values ranging from 6-69 calculated throughout the study population. To test the capability of AISI to assess disease severity, the authors correlated it with each validated index and detected a significant correlation between Hurley staging and AISI score (r: 0.70856; P = 0.0021) (Table 2). The mean AISI score detected in Hurley I patients was 8.33 (SD± 1.94), while an AISI value of 6.00 and 10.00 identified the 25th and the 75th percentile, respectively (Table 3). In Hurley II patients, AISI scored 15.67 as the mean value (SD ± 9.44), with 7.00 and 18.00 as the 25th and 75th percentile, respectively (Table 3). In Hurley III patients, the mean AISI value was 37.20 (SD ± 20.15), while 33.00 and 37.00 were identified as the 25th and 75th percentile, respectively (Table 3). Thus, the authors may design a new disease severity staging classification according to AISI values: mild HS if the AISI score is less than 10; moderate HS if AISI score is between 10 and 18; severe HS if AISI score is higher than 18 (Table 4). Testing AISI with the modified Sartorius score, a significant and high correlation was observed (r: 0.9730; P = <0.00001; Table 2). Similarly, AISI significantly correlated with DLQI (r: 0.8257; P = 0.0221; Table 2).

The authors also investigated the variation of all disease severity assessments throughout a 16-week period. Particularly, the study focused on the 2 dynamic, HS-dedicated, severity measurements, AISI and Sartorius. As shown in Figure 3, clinical improvement or worsening of HS over 16-week timeframe was similarly detected by both AISI and modified Sartorius score.

Additionally, the time necessary to perform each dynamic score (ie, AISI and Sartorius) was evaluated and, notably, performances were almost 2-fold faster using AISI than Sartorius (46.44 ± 19.24 seconds vs 83.2 ± 19.04 seconds; P =1.31 x 10-6).

Hidradenitis suppurativa is a chronic, disabling, negatively QoL-impacting disease. Clinically, HS is characterized by boiling, painful, deeply infiltrated lesions that may evolve in draining abscesses associated with malodorous and staining secretions. These open wounds usually demonstrate a slow and difficult healing process. The clinical picture is usually pleomorphic as other HS-featuring lesions including comedones, fistulas, hypertrophic-keloid scars, 

fibrotic adherence, fibrosclerotic inflammatory plaques peculiarly located on the buttocks, might be observed.

Because these lesions are painful and affect body sites that may limit movement functionality (eg, the axillae and groin), and impair physiological functions (ie, genital areas, breasts, buttocks), HS dramatically interferes with daily activities, having an overall negative impact on QoL and psychosocial attitude. More than other chronic skin disorders, the negative impact on QoL in patients with HS is a hallmark of this disease. Therefore, a disease severity measurement should consider both the clinical picture and the impact on patient’s QoL. Indeed, critical for the management of HS is the availability of an easy assessment tool allowing clinicians to define the severity of the disease, provide evidence about worsening or improvement related to therapy, and consider patient pain, discomfort, and disability. Because of this complexity, the assessment of disease severity is challenging.

The first HS-specific severity assessment score proposed in 1989 was the Hurley staging classification.⁷ It is easy to perform and it gives a static clinical evaluation dissecting 3 stages of severity. Being nondynamic, it is disadvantageous to assess the therapeutic response over time. Additionally it does not include the patient’s rating. The Sartorius score, designed in 2003, was the first validated, dynamic, HS-dedicated tool.¹⁰ It shows the advantage to assess clinical response based on the involved anatomical regions, the number and type of lesions, and the distance between relevant lesions. Nevertheless, it is time-consuming and impractical for use in daily clinical practice.

The HS-PGA is a 6-scale evaluating scale (scores range from 0-5) based on the number of HS lesions (ie, abscesses, draining fistulas, inflammatory nodules, and noninflammatory nodules).¹¹ It is easy to perform, giving an efficient snapshot of the clinical condition, though it does not include a patient-rated assessment.

Recently, other HS-specific assessment tools have been proposed, including the HiSCR, which is strictly related to the therapeutic response.¹² Because it has been designed in the trial setting, it exclusively evaluates patients with at least 3 inflammatory lesions (ie, abscesses and inflammatory nodules) at the baseline. Thus, it does not show the ability to assess a mild form of HS. Furthermore, it is not useful to define disease severity, but exclusively to evaluate clinical response at any time point compared to the baseline condition. Another interesting proposal is represented by the HSSI, a composite, HS-specific index assessing the number of involved body sites, the number of painful and erythematous lesions, a VAS for Pain, and another partial score, named drainage, addressing the impact on QoL.¹³ Though it demonstrates the advantage of including a patient-rated evaluation, it is time-consuming and demanding to perform.

None of the described assessment tools addresses all needs and aspects characterizing HS. Moreover, because the optimal therapeutic strategy is mainly based on disease severity, a valid, easy-to-use, accurate, and reliable assessment tool is needed.

In this setting, the authors sought to design an HS-dedicated, dynamic, simple, composite tool, reflecting both physician-rated and patient-rated evaluations. The AISI includes a scoring system assigning a certain value to each lesion type, representing its severity. The predefinition of a given value for each lesion type is an intrinsic bias that is acknowledged if an assessment tool consists of a scoring system. For instance, in proposing the HSSI, Grant and colleagues¹³ identified 5 categories based on predefined scores. Similarly, other HS assessments arbitrarily propose cutoffs and criteria: HiSCR measures disease severity in patients with at least 3 inflammatory lesions based on predefined criteria; HS-PGA classifies HS in 6 stages based on predefined and arbitrary criteria regarding the number of inflammatory nodules, abscesses, and fistulas;^11,12 and both original and modified Sartorius scores that use predefined and arbitrary distance (cm) from 1 lesion to another.^8,10

Similar to other skin disorders such as psoriasis, where disease severity is assessed by the Psoriasis Area and Severity Index in both clinical trial and real-life practice, the authors proposed the AISI as valid, dynamic, simple, and fast measurement. The high and statistically significant correlations between AISI and the other validated scores proved its reliability. The AISI demonstrated to be rapid (about 47 seconds), easy-to-use, and feasible in real-world practice. Although this study population consisted in a limited cohort of 46 patients, it included not only severe HS (one-third of the cases), but also patients with mild HS, giving the opportunity to successfully test the AISI on patients with HS with varied severity. Being accurate in assessing the mild stage of the disease, the AISI shows an additional advantage compared to previously proposed assessment tools.

A limitation of this study limitation was the short time period of 16 weeks to test AISI variations related to the therapeutic response. Long-term, multicenter, large cohort-based studies will be necessary to confirm these promising findings. Furthermore, it would be of interest to design a trial evaluating the clinical response-to-therapy using the AISI, and to investigate possible therapeutic adjustments based on AISI scoring.

In this study, the authors proposed the AISI as a new disease severity assessment tool for HS. Being easy to use, fast, dynamic, and accurate, it could potentially represent the ideal measurement for HS severity in both real-life and clinical trial settings.

Affiliation: University of Rome Tor Vergata, Rome, Italy

Correspondence:
Andrea Chiricozzi, MD
chiricozziandrea@gmail.com

Disclosure: The authors disclose no financial or other conflicts of interest.