The outcomes that matter most

Investigator-assessed and participant-reported change in acne lesions were prioritised by the committee as critical outcomes because these indicate effectiveness of a specific pharmacological intervention. Scarring of lesions was also chosen as a critical outcome because it can have a negative impact on quality of life. Satisfaction with treatment was another critical outcome as it indicates acceptability of the intervention and also whether the person receiving the intervention perceives an improvement in acne lesions. Relapse of acne lesions after treatment and local side effects were chosen as important outcomes because they indicate effectiveness and safety of a particular intervention.

The quality of the evidence

Risk of bias of the included study was high. Biases were mainly related to the study not reporting randomisation procedure and allocation concealment (both triamcinolone acetonide and betamethasone phosphate studies) and not reporting if outcome assessors were aware of the intervention received by study participants (triamcinolone acetonide study). In the betamethasone phosphate study neither participants nor investigators were blinded.

Benefits and harms

Overall, the evidence on the use of steroids for severe inflamed acne vulgaris lesions was very limited. However, the committee thought it was important to make a recommendation because even though the condition usually affects a small proportion of those with acne vulgaris, it results in severe inflamed acne vulgaris lesions which are very uncomfortable and unsightly. The committee reviewed 2 studies presented in one article from 1983 and considered that, although the study populations were small and the studies were quite old and of poor quality, there were sufficiently positive results to recommend that a dermatologist should consider the use of intralesional triamcinolone acetonide in the treatment of severe inflamed acne vulgaris lesions. In one of the studies they reported on three different concentrations of triamcinolone, the lowest concentration being 0.63mg/ml. All doses gave an improvement, and there was no difference between this dose and the higher two doses of 1.25 and 2.50mg/ml. In that study, they used one tenth of a millilitre (0.1ml) of drug for every cm of the cyst’s diameter. The committee decided that asking people to specifically calculate 0.63 mg/ml from stock solutions might lead to errors in the calculations, and some patients might receive incorrect doses, so they agreed that 0.6mg/ml would be appropriate (0.3ml of the 10mg/ml ampule diluted to 5ml with 0.9% normal saline). In that way the committee put the emphasis on small volume, to ensure that people use an appropriately low amount of drug. It allows an ability to alter the volume and the concentration to account for the lesion they are injecting because the calculation takes into account the diameter. This means that doses are tailored to the individual lesion. The other study reported in the same paper looked at betamethasone phosphate injections suggesting hardly any benefit after one week and no benefit a month after treatment. Taking these factors into consideration the committee did not think that a recommendation about betamethasone phosphate was appropriate.

The committee also discussed possible side effects of triamcinolone acetonide injections, particularly since a small but poor response was observed even in the placebo arm. These could be hypopigmentation if too much drug is given superficially (especially in people with darker skin) or, skin atrophy which can lead to depressed scars and also the risk of an injection in the wrong place. However, they agreed that the recommended amount (0.6mg/mL) is very small and is unlikely to cause side effects. In the committee’s opinion, usually severe inflamed acne lesions respond well to low concentrations of triamcinolone acetonide and flatten out quite quickly as triamcinolone acetonide shortens the life of the lesion and leads to better outcomes for people with acne vulgaris. They also discussed that it is a useful treatment for those with inflammatory acne vulgaris whilst they are waiting, for example, for isotretinoin treatment to start. They therefore decided that the benefits would outweigh possible harms.

The committee agreed that this should be carried out by a member of the dermatology consultant-led team because these treatments could cause skin damage if carried out by a person who may not have the relevant level of expertise.

Even though the study providing the evidence for this topic was conducted a long time ago and it was of limited quality the committee discussed the option of recommending further research. However, they decided not prioritise this for a research recommendation since severe inflamed acne lesions usually affect a small proportion of those with acne making such research difficult to conduct.