Current Measures for the Evaluation of Acne Severity

Jerry KL Tan


Expert Rev Dermatol. 2008;3(5):595-603. 

In This Article

Abstract and Introduction

The overall assessment of acne severity requires consideration of both clinical measures and patient-reported outcomes. This review is focused on recent developments in these interrelated spheres of severity determination. There are multiple current grading scales for active acne and scarring. Furthermore, a number of acne-specific quality-of-life (QoL) measures have been developed. Selection of the most appropriate measures for acne severity is dependent on the intended application. For therapeutic investigations projected for regulatory approval, lesion counting, negotiated and approved global acne scales and complete QoL instruments are advisable. In clinical practice, however, global assessments and indices of QoL instruments may be more practical.

Acne is a common skin disorder afflicting more than 85% of adolescents[1] and can persist or develop over time to affect up to 50% of adults older than 20 years of age. Although the prevalence of acne and severity generally improves with time, worsening was reported by 4% of men and 13% of women.[2] The largest population-based survey of acne involved 105 dermatology residents and just over 20,000 noninstitutionalized people in the USA.[3] This study generated an overall US population acne prevalence estimate of 13%. Of the patients with acne, 17% were younger than 15 years, while 81% were aged 15-44 years. Furthermore, the latter age range accounted for 96% of those with severe acne. In this age group, 71% had no acne, while 19% had mild, 9% had moderate and 1% had severe acne. Thus, of those with acne, approximately a third had moderate-to-severe involvement. Overall, males tended to have a higher prevalence and severity of acne than females. In the USA, acne is the single most common diagnosis for dermatologist visits for people aged from 14 to 45 years.[4] Substantial healthcare resources and consumer expenditures are committed to the treatment of acne. In 2002, the total cost burden of acne and its treatment was estimated to exceed US$1 billion annually.

In 2002, the most comprehensive review of acne research literature was undertaken by the Agency for Healthcare Research and Quality.[5] In this systematic structured review of acne therapy, 4749 acne trials were initially identified by computerized database searches. Articles were subsequently excluded if they did not address treatment, did not include data in humans, addressed conditions other than acne vulgaris, were not original research, were not published in English or were duplicate publications. This exclusion process resulted in 274 trials being selected for further analysis. The lack of standardization in severity reporting was a primary shortcoming identified by this review. The most frequently cited grading systems were based on comparison with photographic standards, text descriptions or lesion counts of the entire face or a portion thereof. As expert advisors of this project had identified acne severity as the most important patient characteristic in treatment profiling, an attempt to standardize these disparate measures was undertaken. The Combined Acne Severity Classification was developed as a tool to assist in further analysis and was not proffered as a scale for severity assessment in future research. This scale comprised three categories:

  • Mild acne: fewer than 20 comedones, or fewer than 15 inflammatory lesions or a total lesion count lower than 30;

  • Moderate acne: 20-100 comedones, or 15-50 inflammatory lesions or a total lesion count of 30-125;

  • Severe acne: more than 5 cysts, or comedone count greater than 100, or a total inflammatory count greater than 50, or a total lesion count greater than 125.

The methodological conclusions of this review were that the acne literature was heterogeneous at multiple levels, including acne severity, outcome assessments and comparison. In assessing disease severity, they further recommended explicit and standard methods of lesion counting, severity ratings and psychometric measurements.

The clinical presentation of active acne varies extensively owing to the multiple features of disease, including primary lesional types, numbers and distribution, density, extent and regions of involvement. When these are combined with similar considerations for secondary lesions, it is evident that grading acne severity is a complex undertaking. In clinical medicine, the primary rationale for determining severity is to guide the selection of the most appropriate therapy. The objectives of acne treatment are to clear and prevent active lesions, reduce the risk of scarring and minimize psychosocial impact. Beyond individual patient care, however, severity determination is an important aspect of basic, clinical and epidemiologic research. In dermatology, while cutaneous examination has largely been the primary basis for severity evaluation, increasing recognition of the intangible consequences of skin disease has led to the development of psychometric instruments. Such measures provide information relevant to the impact of skin disease on social, psychological and other dimensions relevant to the quality of life (QOL) of patients. Inclusion of patient-reported outcomes on the impact of acne provides an additional dimension to understanding the burden of disease.

Despite numerous systems for the classification of acne severity, there is no universal standard.[5,6] The American Academy of Dermatology sponsored Consensus Conference on Acne Classification in 1991 concluded that a strictly quantitative definition of acne severity was not feasible owing to the variable expression of acne features and that acne severity grading be most effectively accomplished by means of a pattern-diagnosis or a global evaluation system.[7] This system was to be based on consideration of lesional type and extent (specifically, extensive papulopustular disease and persistent or recurrent nodules), ongoing scarring, persistent drainage from lesions, sinus tracts, adverse psychosocial impact and recalcitrance to therapy.

The purpose of this review is to update developments in outcome measures of acne severity relevant to clinicians, clinical investigators and regulatory authorities. In particular, the focus is on the measures of acne severity that may be practical for use in the clinic and investigational trials, and which address the elements expounded by the consensus group - specifically regarding the issues of active acne focusing on primary lesions, the extent of acne scarring and psychosocial impact.


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