EVIDENCE-BASED ANSWER:
Single-agent therapy with a very potent or potent topical corticosteroid appears more effective than other topical agents, including vitamin D3 analogues, for treating scalp psoriasis (strength of recommendation [SOR]: A, systematic reviews of randomized controlled trials [RCTs]).
Combined therapy with a vitamin D3 analogue and a potent topical corticosteroid may be slightly more effective than monotherapy with either agent (SOR: B, systematic reviews of RCTs with inconsistent results).
Evidence summary
A 2013 meta-analysis of 26 RCTs with 8020 patients evaluated topical treatments for scalp psoriasis as part of a subanalysis of a larger Cochrane review of psoriasis therapy.1 Only 20 studies reported the severity of disease: 13 studies looked at moderate to severe scalp psoriasis and the others examined mild to severe disease.
Results were reported as standardized mean differences (SMD) and also converted to a 6-point global improvement scale created by the authors to provide a combined endpoint of provider- or patient-assessed improvement in symptoms such as redness, thickness, and scaling. Higher scores indicate more improvement.
Compared with placebo, the very potent corticosteroid clobetasol propionate improved psoriasis by 1.9 points on the 6-point scale (4 trials, 788 patients; SMD= −1.6; 95% confidence interval [CI], −1.8 to −1.3). The potent steroid betamethasone diproprionate improved symptoms by 1.3 points compared with placebo (2 trials, 712 patients; SMD= −1.1; 95% CI, −1.3 to −0.90).
The topical corticosteroids clobetasol, betamethasone diproprionate, and betamethasone valerate improved symptoms more than the vitamin D3 analogue calcipotriol in head-to-head trials. The corticosteroid improvement scores exceeded calcipotriol scores by 0.5 points (1 trial, 151 patients; SMD=0.37; 95% CI, 0.05-0.69), 0.6 points (1 trial, 1676 patients; SMD=0.48; 95% CI, 0.32-0.64), and 0.5 points (1 trial, 510 patients; SMD=0.37; 95% CI, 0.20-0.55), respectively.
Combination therapy with a vitamin D3 analogue and a corticosteroid yielded approximately 0.2 points of improvement over corticosteroid alone (6 trials, 2444 patients; SMD= −0.18; 95% CI, −0.26 to −0.10). Four trials of combination therapy (2581 patients) resulted in 0.5 to 1.2 points of improvement compared with vitamin D3 analogues alone (SMD=0.64; 95% CI, 0.44-0.84). Specific strengths and dosing regimens weren’t reported.
The Cochrane systematic review, using the same outcome reporting methods, provided data on the vitamin D3 analogue calcipotriol compared with placebo for treating scalp psoriasis.2 Calcipotriol resulted in 0.9 points of improvement on the 6-point global improvement scale (2 trials, 457 patients; SMD= −0.72; 95% CI, −1.3 to −0.16).