Interventions for pityriasis rosea

Pityriasis rosea is a scaly, itchy rash that mainly affects young adults and lasts for 2 to 12 weeks. The effects of many available treatments are uncertain. This is an update of a Cochrane Review first published in 2007.

To assess the effects of interventions for the management of pityriasis rosea in any individual diagnosed by a medical practitioner.

We updated our searches of the following databases to October 2018: the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase, and LILACS. We searched five trials registers. We also checked the reference lists of included and excluded studies, contacted trial authors, scanned the abstracts from major dermatology conference proceedings, and searched the CAB Abstracts database. We searched PubMed for adverse effects to November 2018.

Randomised controlled trials of interventions in pityriasis rosea. Treatment could be given in a single therapy or in combination. Eligible comparators were no treatment, placebo, vehicle only, another active compound, or placebo radiation treatment.

We used standard methodological procedures expected by the Cochrane. Our key outcomes were good or excellent rash improvement within two weeks, rated separately by the participant and medical practitioner; serious adverse events; resolution of itch within two weeks (participant-rated); reduction in itch score within two weeks (participant-rated); and minor participant-reported adverse events not requiring withdrawal of the treatment.

We included 14 trials (761 participants). In general, risk of selection bias was unclear or low, but risk of performance bias and reporting bias was high for 21% of the studies. Participant age ranged from 2 to 60 years, and sex ratio was similar. Disease severity was measured by various severity indices, which the included studies did not categorise. Six studies were conducted in India, three in Iran, two in the Philippines, and one each in Pakistan, the USA, and China. The included studies were conducted in dermatology departments and a paediatric clinic. Study duration ranged from 5 to 26 months. Three studies were funded by drug manufacturers; most studies did not report their funding source. The included studies assessed macrolide antibiotics, an antiviral agent, phototherapy, steroids and antihistamine, and Chinese medicine. None of the studies measured participant-rated good or excellent rash improvement. All reported outcomes were assessed within two weeks of treatment, except for adverse effects, which were measured throughout treatment. There is probably no difference between oral clarithromycin and placebo in itch resolution (risk ratio (RR) 0.84, 95% confidence interval (CI) 0.47 to 1.52; 1 study, 28 participants) or rash improvement (medical practitioner-rated) (RR 1.13, 95% CI 0.89 to 1.44; 1 study, 60 participants). For this comparison, there were no serious adverse events (1 study, 60 participants); minor adverse events and reduction in itch score were not measured; and all evidence was of moderate quality. When compared with placebo, erythromycin may lead to increased rash improvement (medical practitioner-rated) (RR 4.02, 95% CI 0.28 to 56.61; 2 studies, 86 participants, low-quality evidence); however, the 95% CI indicates that the result may also be compatible with a benefit of placebo, and there may be little or no difference between treatments. Itch resolution was not measured, but one study measured reduction in itch score, which is probably larger with erythromycin (MD 3.95, 95% CI 3.37 to 4.53; 34 participants, moderate-quality evidence). In the same single, small trial, none of the participants had a serious adverse event, and there was no clear difference between groups in minor adverse events, which included gastrointestinal upset (RR 2.00, CI 0.20 to 20.04; moderate-quality evidence). Two trials compared oral azithromycin to placebo or vitamins. There is probably no difference between groups in itch resolution (RR 0.83, 95% CI 0.28 to 2.48) or reduction in itch score (MD 0.04, 95% CI -0.35 to 0.43) (both outcomes based on one study; 70 participants, moderate-quality evidence). Low-quality evidence from two studies indicates there may be no difference between groups in rash improvement (medical practitioner-rated) (RR 1.02, 95% CI 0.52 to 2.00; 119 participants). In these same two studies, no serious adverse events were reported, and there was no clear difference between groups in minor adverse events, specifically mild abdominal pain (RR 5.82, 95% CI 0.72 to 47.10; moderate-quality evidence). Acyclovir was compared to placebo, vitamins, or no treatment in three trials (all moderate-quality evidence). Based on one trial (21 participants), itch resolution is probably higher with placebo than with acyclovir (RR 0.34, 95% CI 0.12 to 0.94); reduction in itch score was not measured. However, there is probably a significant difference between groups in rash improvement (medical practitioner-rated) in favour of acyclovir versus all comparators (RR 2.45, 95% CI 1.33 to 4.53; 3 studies, 141 participants). Based on the same three studies, there were no serious adverse events in either group, and there was probably no difference between groups in minor adverse events (only one participant in the placebo group experienced abdominal pain and diarrhoea). One trial compared acyclovir added to standard care (calamine lotion and oral cetirizine) versus standard care alone (24 participants). The addition of acyclovir may lead to increased itch resolution (RR 4.50, 95% CI 1.22 to 16.62) and reduction in itch score (MD 1.26, 95% CI 0.74 to 1.78) compared to standard care alone. Rash improvement (medical practitioner-rated) was not measured. The trial reported no serious adverse events in either group, and there may be no difference between groups in minor adverse events, such as headache (RR 7.00, 95% CI 0.40 to 122.44) (all results based on low-quality evidence).

When compared with placebo or no treatment, oral acyclovir probably leads to increased good or excellent, medical practitioner-rated rash improvement. However, evidence for the effect of acyclovir on itch was inconclusive. We found low- to moderate-quality evidence that erythromycin probably reduces itch more than placebo. Small study sizes, heterogeneity, and bias in blinding and selective reporting limited our conclusions. Further research is needed to investigate different dose regimens of acyclovir and the effect of antivirals on pityriasis rosea.