In the Journal of European Academy of Dermatology and Venereology, researchers described a validation study of the use of calcipotriol to identify psoriasis in patients.
The investigators reported that calcipotriol was previously shown to be the treatment of choice for 48% to 54% of patients newly diagnosed with psoriasis, either alone or in combination with topical corticosteroid therapies. They further observed that in situations in which specific data from private practice dermatologists was lacking, calcipotriol was often used as a proxy measure to identify patients with psoriasis. They determined that the validity of using filled calcipotriol prescriptions for epidemiologic identification of patients with psoriasis needed to be examined.
The study cohort consisted of 275 patients (mean age, 56 years; 57.5% female) with psoriasis, identified from a randomly selected population of 3449 adults from the Danish Skin Cohort. A subset of 221 patients had received a clinical diagnosis of psoriasis, with more than half (54.9%) from a dermatologist. The researchers classified the remaining 54 patients as having psoriasis, according to self-reported symptoms.
The investigators looked at the time between the year of reported onset of psoriasis and having the first prescription filled, up to 15 years. The sensitivity of having at least one prescription filled was low (27.6%), with a high specificity (99.2%). Sensitivity was higher in a subset of the 221 patients who had been diagnosed by a physician (33.5%) or dermatologist (43%) whereas specificity remained constant. Sensitivity decreased with higher numbers of filled prescriptions of topical calcipotriol (2 to 4), yet, again, specificity remained stable.
The median time to filled prescription was 2 years after initial onset of psoriasis symptoms, although many patients were obtaining and filling prescriptions for topical corticosteroids several years before their first onset of symptoms defined as psoriasis.
The investigators concluded that having prescriptions of topical calcipotriol filled was associated with a high specificity and positive predictive value in identifying adults with psoriasis but carried a low sensitivity. The accuracy of using first filled prescriptions of topical calcipotriol was considered “reasonably high.” This was not true of topical corticosteroid prescriptions, which may be filled to treat a number of other skin disorders such as pruritis that may occur in the years before psoriasis onset. They suggested that using more than one filled prescription is a better marker, with greater accuracy in identifying psoriasis, but that because of a low constant of sensitivity, calcipotriol is “an [insufficient] proxy in studies where psoriasis is the outcome.”
Egeberg A, Andersen YMF. Use of topical calcipotriol for identification of patients with psoriasis in administrative healthcare data-a validation study [published online October 1, 2019]. J Eur Acad Dermatol Venereol. 2019. doi:10.1111/jdv.15991