Research letter
Overweight, diabetes and disease duration influence clinical severity in hidradenitis suppurativa–acne inversa: evidence from the national Italian registry DOI: 10.1111/bjd.13864 DEAR EDITOR, Hidradenitis suppurativa–acne inversa (HS-AI) is a chronic inflammatory skin condition that involves the folliculopilosebaceous units. Histopathological studies have suggested that the occlusion of the follicular infundibulum and both innate and adaptive immunity play central roles.1,2 Limited data regarding the clinical aspects and prognosis of HS-AI are available.3 This paper presents data collected within the newly implemented Italian registry of patients with HS-AI. This was a cross-sectional study on baseline data of a cohort of consecutive patients with a new diagnosis of HS-AI, prospectively observed within a network of Italian dermatology departments. Presence and recurrence, for at least 6 months, of nodules, abscesses, draining sinuses and secondary retracting scars localized on the axillae, sub- and intermammary areas, inguinal folds, buttocks and perianal areas were considered as inclusion criteria.4 Written informed consent was obtained from the patients, or from their parents for subjects younger than 18 years, before inclusion in the registry. The study was approved by the ethics committee of the Sant’Anna Hospital in Ferrara. The information collected, using a standardized data collection form, included demographic data, anthropometric measures, selected personal habits, clinical history of the disease, clinical features at entry and follow-up, presence of comorbidities, and therapies prescribed for at least 1 month. The severity of HS-AI was assessed by a physician using the Sartorius score.4,5 A short course was run among participants to harmonize Sartorius score calculation, and the inter-rater agreement of independent measures obtained by participants on a small series of patients was judged satisfactory (data not shown). Age-standardized prevalence rates were computed using the 2011 Italian population as a reference. The frequency distribution of selected variables within the HS-AI sample was compared with the distribution in the general population using standardized prevalence ratios along with their 95% confidence intervals (CIs). The Mann–Whitney U-test and Kruskal–Wallis test were used to assess differences across different levels of selected variables for HS severity. To assess which factors were independently associated with HS severity, baseline variables with © 2015 British Association of Dermatologists
a P-value < 010 in the univariate analysis were evaluated in multivariate linear regression models with forward stepwise selection algorithms. The effects of selected factors were expressed in terms of standardized (Pearson) correlation coefficients (q) along with their 95% CIs and P-values. All tests were considered significant at P < 005. From January 2009 to June 2013, 245 patients in seven Italian referral centres for HS-AI were included in the registry; 596% of patients were female, and the age at entry was between 6 and 85 years (mean 334 130), with a mean age at first diagnosis by a physician of 282 118 years, and a mean Sartorius score of 784 661 (Table 1). The mean age at onset of the disease was 213 102 years, and the main affected locations at baseline were the groin/genitals (441%), axillae (347%), buttocks (102%) and trunk (90%). The most frequently reported comorbidities were acne (57%), thyroid diseases (45%) and diabetes (41%). Compared with the general Italian population, adult patients (aged ≥ 18 years) with HS-AI were more frequently overweight or obese (age-standardized prevalence ratio 14, 95% CI 11–19), and the prevalence of current smokers was substantially higher (age-standardized prevalence ratio 25, 95% CI 19–34). There were some significant variations between sexes. Age at onset was higher in male patients (242 127 vs. 194 76, P = 0003), while groin/genital involvement was more frequent in female patients (507% vs. 343%, P = 001). In the univariate analysis, age, duration of disease, diagnostic delay, body mass index (BMI), smoking habits and presence of diabetes were all associated with an increased severity of the disease at baseline (Table 2). In the multivariate analysis, duration of disease ≥ 5 years, obesity (BMI ≥ 30 kg m 2) and the presence of diabetes were maintained as independent factors directly associated with HS-AI severity. Further analysis showed that smoking correlated with both duration of disease and BMI, with a significant linear trend across different levels of the variables (data not shown). Our data show that the implementation of a registry for HS-AI is feasible and could provide useful data to direct disease management. Smoking and obesity have been proposed as risk factors either to trigger or to exacerbate HS-AI.6–8 In our cohort approximately 70% of the patients were current smokers (657%) or ex-smokers (86%), and the number of current smokers was higher than in the general Italian population. However, we lacked a control group of smokers matched for BMI. Smoking has been associated with increased severity of HS-AI in some studies but not others.9,10 In our study smoking British Journal of Dermatology (2016) 174, pp195–197
195
196 Research letter Table 1 Demographics, anthropometric variables, smoking and baseline clinical features of patients included in the registry Characteristic
n (%)a
Patients Age (years), mean SD < 20 20–29 30–39 ≥ 40 Body mass index (kg m 2), mean SD < 200 200–249 250–299 ≥ 300 Smoking habit Yes No Ex-smoker Age at first diagnosis by physician (years), mean SD < 20 20–29 30–39 ≥ 40 Age at onset (years), mean SD < 10 10–19 20–29 ≥ 30 Sartorius score, mean SD < 25 25–49 50–99 ≥ 100 Main affected locations Groin/genitals Axillae Buttocks Trunk Face/neck Thighs Pubis Other locations Comorbidities Acne Dermatitis/eczema Psoriasis Diabetesb Thyroid diseases Other diseases
245 334 31 70 69 70 263 16 94 67 50
130 (129) (292) (288) (292) 55 (70) (414) (295) (220)
153 60 20 282
(657) (258) (86) 118
52 84 56 36 213 10 110 74 40 784 42 44 71 55
(228) (368) (246) (158) 102 (43) (470) (316) (171) 661 (198) (208) (335) (259)
108 85 25 22 9 4 2 5
(441) (347) (102) (90) (37) (16) (08) (20)
14 8 6 10 11 35
(57) (33) (24) (41) (45) (143)
Multivariate analysisa
Univariate analysis
a
Numbers may not add up to the total due to missing data. Defined according to the following criterion: diagnosis by physician and needing diet and/or medication. All of the cases were classified as type II diabetes.
b
habits (smokers and ex-smokers) were associated with more severe disease in the univariate analysis but not in the multivariate analysis. Whether the disease course is influenced by the cessation of smoking is not known.11
British Journal of Dermatology (2016) 174, pp195–197
Table 2 Univariate and multivariate analysis of hidradenitis suppurativa severity, as assessed by Sartorius score at baseline and potential prognostic factors
Sartorius score, mean SD P-valueb q (95% CI) Sex Male 839 713 Female 745 623 Age (years) < 25 505 438 25–39 772 605 ≥ 40 1056 758 Age at onset (years) < 15 804 702 15–24 736 612 ≥ 25 853 728 Duration of disease (years)