“…It found a significant improvement in disease severity (v placebo) with calcipotriol (17 studies; standardised mean difference (SMD) −0.96, 95% confidence interval −1.12 to −0.77), calcitriol (seven studies; −0.92, −1.54 to −0.29), and tacalcitol (four studies; −0.73, −1.09 to −0.37). 8 A European guidelines' systematic review of 19 studies (RCTs and observational studies) found that 25-58% of patients with mild to moderate chronic plaque psoriasis treated with vitamin D or its analogues showed a "significant improvement" or "near clearance" after twice daily application for six to eight weeks. 9 Absolute efficacy, measured using investigator's assessment of clear or nearly clear, gives a number needed to treat (NNT) of 7 (4 to 18; three moderate quality RCTs) for once daily calcipotriol, 2 (2 to 3; four moderate quality RCTs) for twice daily calcipotriol, 3 (1 to 7; two moderate quality RCTs) for twice daily calcitriol, and 8 (3 to 56; one low quality RCT) for once daily tacalcitol.…”