Particular care should be taken not to accept quantitative scales at face value. Scales that combine several objective clinical signs mixed up with symptoms into an overall scoring system have been very fashionable in dermatology RCTs in the past 30 years yet, despite their objective ring, they have rarely been tested for validity.13 More importantly, such composite scales are often difficult to translate into clinical practice. What, for instance, does a difference of 8 units (P<0-05) in mean change of PASI score from baseline between two treatments mean to you? Is the scale linear (i.e. does a PASI score of 30 mean "twice as bad" as a score of 15) as in other continuous variables such as height and weight? Should different components of these scales be added or multiplied by extent? Does a lot of psoriasis over the covered areas of the body mean more distress than a little bit of psoriasis on the backs of the hands and face?
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Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.