Table 1

Outcome measures selected

Outcome measureNumber of total items (scale)Domains (number of items within each domain)Description
Acne-QoL15–1719 (7 point)Symptoms (5)
Role emotional (5)
Role social (4)
Self-perception (5)
Of available PROMs, the Acne-QoL is the most extensively validated for facial acne. The questions ask respondents to score their answer based on the last week. For each item, the answers range on a 7-point scale. The scale points are labelled from ‘extremely’ to ‘not at all’, except three of the symptoms subscale items responses which are labelled from ‘extensive’ to ‘none’. The higher the score, the better the respondent’s QoL.
Skindex-1619–2116 (7 point)Symptoms (4),
Emotions (7),
Functioning (5)
Skindex was designed to be used in a range of skin conditions and is not acne specific, although it has been used in published acne studies. It covers similar domains to the Acne-QoL, but with more focus on appearance. The 29-item Skindex21 has been more extensively validated than the 16-item version, which has not been validated specifically for acne. However, the shorter version would be preferable in a clinical trial setting, where questionnaire burden can be a concern for participants.
In the Skindex-16, the questions ask the respondent how bothered they have been by the items mentioned in the last 7 days. The scale points are labelled with ‘Never bothered’ for 0 and ‘always bothered’ for 6 for each item. The scores are converted to a linear scale ranging from 0 to 100; the higher the scores, the poorer the respondent’s QoL.
CompAQ1820 (9 point)Symptoms (4) Social (judgement by others) (4)
Social interactions (4)
Psychological/ emotional (4) Treatment concerns (4)
The CompAQ is a recently developed outcome measure and, unlike the other two measures, can be used for both facial and truncal acne. The CompAQ was developed in parallel with the ACORN initiative to secure consensus about core outcome domains and has not yet been externally validated.
For each item, the respondents are asked to choose how much the item relates to them. The scale points are labelled on every other number with 0 as ‘never’ and 8 as ‘all the time’ and therefore, the higher the score, the poorer the respondents QoL.
Patient Global Assessment and the Patient Global Assessment of Change(6 point)We also included a patient global assessment of their acne and, at 6 weeks, a patient global assessment of the change in their acne to assist in the assessment of sensitivity to change. The questions used were ‘How would you describe your acne at the moment’, with responses ranging from clear to very severe, and ‘How would you describe the change in your acne in the last 6 weeks?’, with responses ranging from ‘Completely cleared’ to ‘Worse’. Participants were encouraged to take a photo at baseline to refer to at the 6-week follow-up to help them answer this question.
  • Acne-QoL, Acne-specific Quality of Life; ACORN, Acne Core Outcomes Research Network; CompAQ, Comprehensive Acne Quality of Life Scale; PROMs, patient-reported outcome measures; QoL, quality of life.