The Sartorius score was proposed in 2003 by Sartorius, Lapins, Emtestam and Jemec as a set of uniform outcome variables for reporting treatment effects in hidradenitis suppurativa (Sartorius et al. 2003). Unlike the static Hurley classification, it is a regional, count-based score: each anatomical region involved earns 3 points, every lesion in the region adds points by type, the longest distance between two relevant lesions in the region adds a band score, and a further penalty is added when the lesions are not clearly separated by normal skin. The regional scores are summed and the total has no upper limit. In the original version, nodules score 2, fistulas 4, scars 1 and other lesions 1; the distance bands are 2, 4 and 8 points for under 5 cm, 5 to 10 cm and over 10 cm; and lesions that are not separated by normal skin add 6 points.

The modified Sartorius score, published in 2009 as the modified hidradenitis suppurativa score (Sartorius et al. 2009), simplified the lesion items and rebalanced the points so that the score reflects inflammatory activity more closely. On the 2009 form, the regions are the right and left axilla, groin and gluteal region plus one row for any other region; inflammatory nodules or abscesses score 1 point each and draining fistulas 6 points each; scars and other lesions are not counted; the distance bands are 1, 3 and 9 points; and a region whose lesions are not separated by normal skin, that is a Hurley III region, adds 9 points. The size of the lesion replaces the distance item when only one lesion is present, and an uninvolved region scores 0, so the smallest non-zero regional score is 5. This version is the one cited by the IHS4 validation study (Zouboulis et al. 2017), by the European S1 guideline (Zouboulis et al. 2015) and by current clinical trial protocols, and it is the default implemented here; the 2003 original is available as a second mode.

Several other point sets circulate under the same name, so the version should always be stated alongside the score. Revuz (2007, 2009) proposed a modification with five paired regions, abscesses and draining fistulas at 4 points, other lesions at half a point and a zero distance score for inactive disease, and the adalimumab development programme used a further variant with 12 body areas and 2003-type lesion points, which explains the high baseline means reported in those trials (Kimball et al. 2012). Scores from different versions are not interchangeable, and a follow-up score is only comparable with a baseline scored with the same version.

The interobserver concordance of the 2009 score was 0.95 when 23 patients were scored independently by four dermatologists (Sartorius et al. 2010), and the score correlates with Hurley stage, with smoking and body mass index (Sartorius et al. 2009) and with the Dermatology Life Quality Index. No responder threshold or minimal important difference has been validated for any version (Ingram et al. 2016), so trials report the absolute or percentage change from baseline, and the percentage improvement shown by this calculator is descriptive only. The score is more time-consuming than IHS4 and Hurley staging, gives large weight to draining fistulas and to confluent disease, and its open upper limit makes severity bands impractical; in practice it is used for visit-to-visit comparison rather than for classification.