For Residents

Skin Scores: A Review of Clinical Scoring Systems in Dermatology

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Scoring systems are emerging in dermatology to help guide clinical decision-making. This article discusses 4 scoring systems that help prognosticate cases of Stevens-Johnson syndrome/toxic epidermal necrolysis, screen for psoriatic arthritis, differentiate cellulitis from pseudocellulitis, and determine the appropriateness of Mohs micrographic surgery (MMS).

Resident Pearls

  • Mortality from Stevens-Johnson syndrome/toxic epidermal necrolysis can be estimated by calculating the SCORTEN at the end of days 1 and 3 of hospitalization.
  • The Psoriasis Epidemiology Screening Tool (PEST) assists with triaging which patients with psoriasis should be evaluated for psoriatic arthritis by a rheumatologist.
  • The ALT-70 score is helpful to support one’s diagnosis of cellulitis or pseudocellulitis.
  • The Mohs appropriate use criteria (AUC) score 270 different clinical scenarios as appropriate, uncertain, or inappropriate for Mohs micrographic surgery.



The practice of dermatology is rife with bedside tools: swabs, smears, and scoring systems. First popularized in specialties such as emergency medicine and internal medicine, clinical scoring systems are now emerging in dermatology. These evidence-based scores can be calculated quickly at the bedside—often through a free smartphone app—to help guide clinical decision-making regarding diagnosis, prognosis, and management. As with any medical tool, scoring systems have limitations and should be used as a supplement, not substitute, for one’s clinical judgement. This article reviews 4 clinical scoring systems practical for dermatology residents.

SCORTEN Prognosticates Cases of Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis

Perhaps the best-known scoring system in dermatology, the SCORTEN is widely used to predict hospital mortality from Stevens-Johnson syndrome/toxic epidermal necrolysis. The SCORTEN includes 7 variables of equal weight—age of 40 years or older, heart rate of 120 beats per minute or more, cancer/hematologic malignancy, involved body surface area (BSA) greater than 10%, serum urea greater than 10 mmol/L, serum bicarbonate less than 20 mmol/L, and serum glucose greater than 14 mmol/L—each contributing 1 point to the overall score if present.1 The involved BSA is defined as the sum of detached and detachable epidermis.1

The SCORTEN was developed and prospectively validated to be calculated at the end of the first 24 hours of admission; for this calculation, use the BSA affected at that time, and use the most abnormal values during the first 24 hours of admission for the other variables.1 In addition, a follow-up study including some of the original coauthors recommends recalculating the SCORTEN at the end of hospital day 3, having found that the score’s predictive value was better on this day than hospital days 1, 2, 4, or 5.2 Based on the original study, a SCORTEN of 0 to 1 corresponds to a mortality rate of 3.2%, 2 to 12.1%, 3 to 35.3%, 4 to 58.3%, and 5 or greater to 90.0%.1

Limitations of the SCORTEN include its ability to overestimate or underestimate mortality as demonstrated by 2 multi-institutional cohorts.3,4 Recently, the ABCD-10 score was developed as an alternative to the SCORTEN and was found to predict mortality similarly when validated in an internal cohort.5

PEST Screens for Psoriatic Arthritis

Dermatologists play an important role in screening for psoriatic arthritis, as an estimated 1 in 5 patients with psoriasis have psoriatic arthritis.6 To this end, several screening tools have been developed to help differentiate psoriatic arthritis from other arthritides. Joint guidelines from the American Academy of Dermatology and the National Psoriasis Foundation acknowledge that “. . . these screening tools have tended to perform less well when tested in groups of people other than those for which they were originally developed. As such, their usefulness in routine clinical practice remains controversial.”7 Nevertheless, the guidelines state, “[b]ecause screening and early detection of inflammatory arthritis are essential to optimize patient [quality of life] and reduce morbidity, providers may consider using a formal screening tool of their choice.”7

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