Pain assessment in HS trials may require information on pain recall, intensity

Details on pain recall may be necessary to supplement the numerical rating and VAS for pain assessment in clinical trials of hidradenitis suppurativa, according to a study.

“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),” Samar B. Hasan, MD, of the division of infection & immunity at Cardiff University in Wales, and colleagues wrote.

In the review, Hasan and colleagues assessed randomized control trials to determine whether certain pain assessment tools — including the numerical rating scale (NRS) and VAS — can inform HISTORIC for measuring pain intensity in studies of patients with HS. Trials of the NRS in painful skin conditions and the VAS in rheumatoid arthritis were included.

Eligible studies were randomized controlled trials with at least 10 participants.

More than three-quarters (78%) of eligible trials for painful skin conditions were those in patients with herpes zoster. Eleven percent of the studies were in patients with HS, whereas 5% were in epidermolysis bullosa, 3% in pemphigus vulgaris, 2% in acne vulgaris and 1% in pyoderma gangrenosum.

The NRS and VAS were used in 68% of these trials in painful skin conditions.

The researchers also aimed to assess parameters for pain recall. Results showed that 77% of trials in painful skin conditions and 87% of those in rheumatoid arthritis did not specify the recall window for pain. The most common recall window specified in trials of painful skin conditions was 24 hours, according to the findings.

Further findings showed that for the painful skin condition studies, 33% assessed patients for maximum pain intensity, whereas 3% assessed for average pain intensity.

No details on pain intensity were included in 87% of rheumatoid arthritis trials.

“Measuring the maximum intensity of pain several times over a specific period will most likely produce more reliable data than a single average assessment,” the researchers wrote. “It has been shown that worst pain intensity correlates better with functional interference due to pain, compared with average and least pain scores.”

Pain outcomes were reported as a mean difference in 76% of the skin condition trials and 75% of rheumatoid arthritis trials.

Further findings showed that 10% of skin condition trials and 11% of rheumatoid arthritis trials reported pain outcomes as a proportion of patients reaching a desirable level. Conversely, 1% of skin condition trials and 2% of arthritis trials reported pain as a function of the number needed to treat, according to the results.

“While pain NRS and VAS are standard methods to measure pain intensity in [painful skin conditions], key details such as the recall window are often omitted and there is no consensus on how to report pain NRS data,” the researchers concluded.