With different treatment options offered for ‘limited or mild’, ‘moderate’ and ‘severe’ alopecia areata, in this piece we look at how alopecia areata severity is graded by clinicians.

Typically, the severity of alopecia areata is graded using the Severity of Alopecia Tool (SALT). This tool was developed to standardise the quantification of hair loss across the scalp. It does this by dividing it into four quadrants: left side, right side, top and back. For each region, the percentage of the area affected by hair loss is measured. These figures are then multiplied by a weighting factor for each scalp region. This graphic from The University of Manchester and Salford Royal NHS Foundation Trust explains how a SALT score is calculated.

Simply speaking, SALT scores relate to the percentage of total hair loss across the scalp. For example, a SALT score of 20 means the patient has 20% total scalp hair loss, and a SALT score of 95 means 95% scalp hair loss.

We understand that most clinicians agree with the following severity gradings based on SALT score:

• SALT score of 1-20 = Mild/Limited Alopecia Areata
• SALT score of 21-49 = Moderate Alopecia Areata
• SALT score of 50-94 = Severe Alopecia Areata 
• SALT score of 95-100 = Very Severe Alopecia Areata

To determine if a treatment was a success, older clinical trials used a relative improvement in SALT score of 50% or 90%, from the start of the trial. However, recognising that patients may perceive this differently, US researchers asked patients with greater than 50% scalp hair loss what they would consider a treatment success (short of complete (100%) regrowth). From this group, most answered that approximately 70-90% scalp hair growth would be a success. As a result, recent clinical trials for the new JAK inhibitor medicines have treated success as reaching a SALT score of 20 or less. However, we know that this does not reflect all people with alopecia areata, and the amount of hair loss on the scalp is not the only determinant in how someone experiences alopecia areata.

A limitation of the SALT grading system is that it focuses entirely on the percentage of hair loss on the scalp but doesn’t factor in other considerations. We know that many people are affected by other factors, such as facial hair involvement and psychological distress. A recent consensus study by 64 international alopecia experts established a list of factors which potentially worsen alopecia areata severity outcomes. These include:

• Disease duration of 12 months or more
• 3 or more relapses
• Inadequate response to topical or systemic treatments
• Rapid disease progression
• Difficulty in cosmetically concealing hair loss
• Facial hair involvement (eyebrows, eyelashes, and/or beard)
• Nail involvement
• Pattern of the hair loss (e.g. diffuse, ophiasis)
• Impaired quality of life
• History of anxiety, depression, or suicidal ideation due to or exacerbated by alopecia areata

As a result of this study, the group intend to develop a new Alopecia Areata Severity and Morbidity Index (ASAMI) tool, which can take these factors into account when grading. However, this tool will still need to be developed and validated before it may eventually enter routine practice.

These tools are needed to identify the most appropriate candidates to receive a medicine. It will be up to doctors to determine the severity level of a patient’s alopecia areata and establish whether they meet the required level for a particular treatment protocol.

Besides alopecia severity, doctors will also need to assess many other health-related factors to determine whether a patient is a candidate for a particular type of treatment.