Abstract: Fifteen RCTs were included, giving a total of 473 participants with ELP (study sizes ranged between 8-94). All studies involved oral sites only. Six studies included participants with non-erosive lichen planus but only the erosive subgroup was included for intended subgroup analysis. We were unable to pool data from any of the nine studies with only ELP participants or any of the six studies with the ELP subgroup, due to small numbers and the heterogeneity of the interventions, design methods, and outcome variables between studies. One study involving 50 participants found that 0.025% clobetasol propionate administered as liquid microspheres significantly reduced pain compared to ointment (Mean difference (MD) -18.30, 95% confidence interval (CI) -28.57 to -8.03), but outcome data was only available in 45 participants (high risk of performance bias for blinding of participants, low/unclear risk of bias overall). However, in another study, a significant difference in pain was seen in the small subgroup of 11 ELP participants, favouring ciclosporin solution over 0.1% triamcinolone acetonide in orabase (MD -1.40, 95% CI -1.86 to -0.94) (high risk of performance and detection bias due to likely lack of blinding, low/unclear risk of bias overall). Aloe vera gel was 6 times more likely to result in at least a 50% improvement in pain symptoms compared to placebo in a study involving 45 ELP participants (Risk ratio (RR) 6.16, 95% CI 2.35 to 16.13) (low risk of bias overall). No significant difference was seen in Physician Global Assessment in these three studies. In a small single study involving 20 ELP participants, 1% pimecrolimus cream was 7 times more likely to result in a strong improvement as rated by the Physician Global Assessment when compared to vehicle cream (RR 7.00, 95% CI 1.04 to 46.95) (low risk of bias overall). In a study involving a small subgroup of 8 ELP participants, a significant difference was seen for an improvement in the severity of the disease as rated by the Physician Global Assessment, in favour of the ciclosporin group when compared to the vehicle (MD -1.40, 95% CI -1.86 to -0.94) (unclear risk of selection bias for allocation concealment, overall risk of bias low). No statistically significant benefits were shown for topical tacrolimus or fluticasone spray in two separate studies of 29 and 44 participants respectively. There is no overwhelming evidence for the efficacy of a single treatment, including topical steroids, which are the widely accepted first-line therapy for ELP. Several side-effects were reported, but none were serious. With topical corticosteroids, the main side-effects were oral candidiasis and dyspepsia. This review suggests that there is only weak evidence for the effectiveness of any of the treatments for oral ELP, whilst no evidence was found for genital ELP. More RCTs on a larger scale are needed in the oral and genital ELP populations. We suggest that future studies should have standardised outcome variables that are clinically important to affected individuals. We recommend the measurement of a clinical severity score and a participant-rated symptom score using agreed and validated severity scoring tools. We also recommend the development of a validated combined severity scoring tool for both oral and genital populations.

Plain-language summary: This review looked at the effectiveness of treatments for ELP and included 15 studies, with 473 participants with ELP. All involved oral, but not genital, disease. Many studies were excluded either because they were not randomised controlled trials (where participants are divided into two groups at random) or because they recruited participants with all types of lichen planus, rather than just the erosive subtypes. All of these studies recruited small numbers of participants (12 to 94) and used a variety of different assessment methods and timings; hence, it was not possible to combine or compare results between studies directly. We found only weak evidence for the effectiveness of any of the treatments for oral ELP. None of the studies involved genital or oesophageal disease; hence, no evidence was found for the treatment of these conditions. One small study found that 0.025% clobetasol propionate (a very potent topical steroid) administered as a spray significantly reduced pain when compared to ointment. In another study, a significant difference in pain was seen in the small subgroup of 11 ELP participants, favouring ciclosporin solution over 0.1% triamcinolone acetonide in orabase (a potent topical steroid). In a study involving 45 ELP participants, aloe vera gel was 6 times more likely to result in at least a 50% improvement in pain symptoms compared to placebo. In a study involving a small subgroup of 8 ELP participants, a significant difference was seen for an improvement in the severity of the disease in favour of the ciclosporin group when compared to the vehicle. Several side-effects were reported, but none were serious. With topical corticosteroids, the main side-effects were oral candida (yeast) infection and pain or discomfort in the upper abdomen. Temporary burning was a common side-effect reported with tacrolimus 0.1% ointment and pimecrolimus 0.1% cream. Overall, there was no overwhelming evidence for the effectiveness of any single treatment, including topical steroids, which are the widely accepted first-line therapy for ELP. This was mainly due to the lack of good-quality, well-conducted trials and small participant numbers. Another Cochrane review has already assessed interventions for lichen planus affecting the mouth.