Assessing Acne

By Dr Aneesha Ahmad / 29 Jul 2020

Aesthetic practitioner Dr Aneesha Ahmad provides an introduction to acne assessment

Acne is a common skin condition which affects up to 95% of adolescents and can occur in up to 43% of adults in their 30s.1,2,3 Despite being more common and severe in male teenagers, it is found to be more frequent and indeed persistent for adult females.2 Acne is commonly found on the face with clusters usually on the cheeks, chin and forehead, although it can also affect the back and chest as these anatomic areas also have a high density of pilosebaceous units. It is caused primarily by inflammation of the pilosebaceous units, resulting in both inflammatory and non-inflammatory lesions.

There are thought to be four main processes involved in the development of acne: comedones, microcomedones, papules, pustules and nodules. If left untreated, acne can cause scarring, so it is important for practitioners to be able to identify acne in its mildest form to prevent it from worsening and causing scar formation.3 For this reason, it is essential for an accurate assessment of acne to be carried out, and for clinicians to feel competent in doing so.


Acne development, or pathogenesis, takes place in the pilosebaceous unit, which comprises the hair follicle, sebaceous gland and its exit on to the skin surface as a ‘skin pore’ (Figure 1). Altered keratinocyte proliferation causes follicular plugs to form at the hair follicle, also known as micro-comedones or whiteheads. These micro-comedones are the target lesion for successful treatment of acne. This process can be further exacerbated by excess sebum production, secondary to androgens during puberty. Proliferation of the anaerobic propionibacterium acnes bacterium within the hair follicles causes further inflammation and lesions to form. Other factors thought to play a role in the development of acne include diet, hormonal changes, genetics and drugs.3,4

There are two different types of lesions that practitioners need to be familiar with when assessing acne. The first are inflammatory lesions, which are comedones that can be open (blackheads) or closed (whiteheads) and the second are non-inflammatory lesions, such as papules, pustules and nodules or cysts. Blackheads are caused by enlarged and stretched pores with a build-up of excess melanin and oxidised oil.1 Papules and pustules are superficial lesions which are raised and less than 5mm in diameter; pustules are fluid filled whereas papules are not. Nodules and cysts are larger than 5mm in diameter. Cysts are fluctuant swellings, lined by epithelium, containing pus, fluid or keratin, whereas nodules are similar to papules but larger in size (5-10mm). Cysts can be painful and may leave large scars.4 It is important to recognise the different types of lesions which may be present when assessing patients with acne as it will help determine the most suitable and effective treatment approaches.6,7

Clinical assessment of acne

There are more than 25 grading systems for acne which have been published to date, but there is no universal method for grading or assessing acne.1,8 Due to the dynamic, complex and fluctuating acute and chronic symptoms, acne can be difficult to evaluate. There are four main recognised methods of assessing acne:9

1) Lesion counting

2) Global acne severity grading

3) Subjective self-assessment

4) Multimodal imaging using UVA lamps, fluorescent lights, polarisers and a digital camera

The methods that are most used in clinical settings are lesion counting and acne severity grading.10

Lesion counting

Lesion counting involves recording the number of different types of lesions to determine overall severity. It is an objective method and thought to be more accurate, particularly if carried out by the same clinician each time, as it involves recording the specific number of each type of lesion, describing severity down to each individual lesion level.6,9,10 However, due to the level of detail involved, it can be more time consuming. This method can be used in clinical trials or to determine effect of treatment on individual lesions, although it may come across as more intrusive to patients than grading as lesions may be palpated if necessary, which some patients may find uncomfortable.6 It does not take into account other features such as concentration, distribution and size of lesions and erythema. This method relies heavily on the practitioner’s ability to recognise lesions and assess confidently.

An example of such a system is the Combined Acne Severity Classification, comprising three categories, and is widely used by practitioners:3,9,10

Mild acne: fewer than 20 comedones or less than 15 inflammatory lesions with 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 five cysts, total comedone count more than 100, or total inflammatory count greater than 50 or total lesion count greater than 1256

Severity grading systems

Grading systems involve observing dominant lesions and estimating the extent of involvement. It is often criticised as being a subjective system and less sensitive to change and therefore less accurate, but Adityan et al. and Agnew et al. consider this method to be more useful in a clinical setting as it is less time consuming.8-11 The efficacy of treatment on individual lesions cannot be estimated.

Examples of different grading systems include the Leeds Revised Grading System and the Global Acne Grading system.1,6 The Leeds Revised Grading System, established in 1998, uses photographs in order to grade acne of the face, back and chest. There are 15 facial grades and eight each for the chest and back. These grades are based on a selection of more than 1,000 photographs from a panel of three dermatologists and four acne assessors. The clinician compares the photographs in the system to the clinical appearances of their patient. However, this system can be difficult to apply in clinical practice due to the varying representations of severity and the large number of categories within each region.6 A more commonly used system is the Comprehensive Acne Severity Scale, which has a strong correlation to the Leeds Grading System and is simpler to use (Table 1).7

Current guidelines

The current National Institute for Health and Care Excellence (NICE) guidelines in the UK acknowledge that although there is no universal system used to score acne, categorising into mild, moderate and severe may help to ensure treatments are selected correctly and to allow treatment response to be monitored.4

With similar classification to the Combined Acne Severity Classification, the following system is suggested by NICE and is slightly different:4

Mild: predominantly non-inflamed lesions (open and closed comedones) with few inflammatory lesions

Moderate: more widespread with an increased number of inflammatory papules and pustules

Severe: widespread inflammatory papules, pustules and nodules or cysts. Scarring may also be present

Psychological assessment

It is also important for practitioners to acknowledge and assess the psychological impact of acne, as well as the physical implications. Studies have shown that in some cases, even mild to moderate acne may be associated with significant depression and suicidal ideation and the effects of acne are comparable to other chronic diseases such as asthma, epilepsy, diabetes and asthma.8,12,13,14 Measuring quality of life allows practitioners to understand the patients’ perspective of disease and there are many scales which allow clinicians to assess the impact of acne upon quality of life.

There are several examples of psychological assessment tools, including the Acne Disability Index, the Acne Quality of Life scale and the assessment of psychological and social effects of acne.

One of the more popular scales is the Cardiff Acne Disability Index (Table 2), which comprises five questions.6,8 A score of 0 equates to no impairment, 1-5 mild impairment, 6-10 moderate impairment and 11-15 severe impairment.

Early identification of patients with acne who may be at risk of impaired quality of life allows practitioners to take early intervention such as psychological support, in addition to medical management, thus improving social and psychological wellbeing of such patients.

Putting it into practice

Although there is no agreed upon universal method for assessing acne, it is apparent that clinicians should be confident in identifying and distinguishing between different lesions to correctly treat acne. Clinicians should choose a method of assessment that they are comfortable and confident with. It is vital that the impact on the quality of life of such patients is taken into account as psychological support is often needed. Ultimately, the goal in the management of acne is alleviating symptoms, clearing lesions, limiting disease progression and avoiding scar formation, alongside alleviating any negative impacts on quality of life. Accurate assessment of the condition therefore provides the cornerstone for the correct management of acne.

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