An Open Label Prospective Randomized Trial to Compare the Efficacy of Coal Tar-salicylic Acid Ointment Versus Calcipotriol/Betamethasone Dipropionate Ointment in the Treatment of Limited Chronic Plaque Psoriasis

Sir,

I have read your published trial on the comparison of coal tar-salicylic acid ointment versus calcipotriol/betamethasone dipropionate ointment with great interest.[1] That trial covers a long standing gap of evidence in the spectrum of trials in topicals in psoriasis.

Many attempts are being made to compare trials in the meta-analysis, systematic reviews, and guidelines. To do this well, sufficient data needs to be provided in the trials and published study results must be reported in a comparable manner.

As you mention yourself, the high drop-out rate in your trial is a limitation. However, your reporting on the management of the drop outs with respect to data analysis could be improved. I would invite you, to report in a response to this letter, on the following aspects: (a) State the selected handling of drop outs (in your case per protocol analysis?) (b) if possible, provide reasons for dropping out (c) provide information if any patients where excluded because they did not meet the at least 25% improvement criterion at week 8 (d) report also % of psoriasis area and severity index (PASI) 50 and PASI 75 responder and not only mean PASI reduction (e) consider providing the data also with a different approach for drop out management, e.g., last observation carried forward or nonresponder imputation.

Adding these data would largely improve the value of your trial with respect to integrating it into the scope of systematic reviews, meta-analysis and guidelines recommendations.