Figure 2. Proposed 9-Point Multidimensional Acne Global Grading System.

Primary lesions and secondary changes can be encoded into a score by first counting lesions (nodules, papules/pustules, and comedones), choosing the highest corresponding row, and then selecting the degree of secondary changes (and choosing the correct combination). The dashed lines indicate any possible entry (ie, the final severity is independent of that specific feature/variable). For example, if papules or nodules are present, the number of comedones is no longer relevant to the score. Similarly, if scars and inflammation are both present, the degree of postinflammatory hyperpigmentation is also no longer relevant to the score. For nodule quantifiers, few indicates 2 to 3; some, 4 to 6; and many, more than 6. For papule/pustule quantifiers, few indicates 1 to 3; some, 4 to 8; and many, more than 8. For comedone quantifiers, few indicates 1 to 3; some, 4 to 12; and many, more than 12. Scars and inflammation should be categorized into none, mild/moderate, or severe. Postinflammatory encodes any postinflammatory color changes and should be marked yes if any of the following cues are present: focal color changes and/or diffuse erythema not associated with primary acne lesion activity; hyperpigmentation; and redness, dryness, or color due to treatment. Mild + allows for differentiation of severe comedonal acne: if comedones are covered, the classification becomes severe comedonal; otherwise, the classification is the same as mild. An additional (lower-left) entry includes older acne cases that have completely cleared (only valid with >0 scars).