Pain measurement in painful skin conditions and rheumatoid arthritis randomized controlled trials: a scoping review to inform pain measurement in hidradenitis suppurativa

BACKGROUND: Pain is the most common and bothersome symptom experienced by people with hidradenitis suppurativa (HS) and has been prioritized as an outcome domain by the HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC). OBJECTIVES: To perform a scoping review of pain measurement in randomized control trials (RCTs) of painful skin conditions (PSCs) and use of the pain numerical rating scale (NRS) and visual analogue scale (VAS) in rheumatoid arthritis RCTs, to inform the efforts of HISTORIC to reach consensus on how to measure pain intensity in HS trials. METHODS: A search was conducted on several publication databases. Inclusion criteria were RCTs with a minimum of 10 participants that measured pain intensity. RESULTS: Pain NRS and VAS were used in 68% of PSC trials. Respectively, 77% and 87% of PSC and rheumatoid arthritis RCTs did not specify the recall window. The commonest recall window in PSCs when specified was 24 h. In total, 33% of PSC trials assessed maximum pain intensity and 3% average pain intensity, while 87% of rheumatoid arthritis trials did not provide details. Pain data were reported as mean difference by 76% of PSC trials and 75% of rheumatoid arthritis trials. Respectively, 10% and 11% of PSC and rheumatoid arthritis studies reported pain as the percentage of patients reaching a desirable state and only 1% and 2% reported number needed to treat. CONCLUSIONS: While pain NRS and VAS are standard methods to measure pain intensity in PSCs, key details such as the recall window are often omitted and there is no consensus on how to report pain NRS data. What is already known about this topic? Pain is the most burdensome symptom experienced by patients with hidradenitis suppurativa and has been prioritized as an outcome domain by the HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC). What does this study add? Our review shows substantial variation in how pain numerical rating scale (NRS) and visual analogue scale are utilized in clinical trials. This variation restricts meta‐analysis of pain intensity results. There is a need for consensus regarding the recall window for pain NRS and maximum vs. average pain, and whether current pain should be measured.