A new screening tool for detecting early psoriatic arthritis in patients with psoriasis that combined the “most discriminative questions” from several other questionnaires performed as well as the Psoriasis Epidemiology Screening Tool (PEST) for detecting the disease.
“The CONTEST questionnaire was developed using the best performing items from three other screening questionnaires in the hope that it would perform better than its originators,” Laura Coates, MBChB, PhD, of the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences at the University of Oxford, England, and her coauthors wrote in the Journal of the European Academy of Dermatology and Venereology. “In development this was partly correct but the current study does not support this – statistically there was no difference between PEST and CONTEST in terms of ability to detect psoriatic arthritis [PsA] in patients with psoriasis.”
In an observational, cross-sectional study, Dr. Coates and her colleagues analyzed the rate of PsA in 159 patients with psoriasis from November 2013 to March 2017 at four different secondary care dermatology centers in Leeds, Bath, Bradford, and Salford in England. (At the time of the study, Dr. Coates was a visiting rheumatologist at the Leeds Institute of Rheumatic and Musculoskeletal Medicine.) Patients were a minimum of 18 years old, did not have a diagnosis of inflammatory joint disease, and had a mean age of 29 years at diagnosis of psoriasis. The patients completed the Psoriatic Arthritis Quality of Life questionnaire, Health Assessment Questionnaire, and Dermatology Life Quality Index, as well as the CONTEST and PEST questionnaires. Patients were assessed by a dermatologist to determine psoriasis type and medication, and then were seen by a rheumatologist to determine whether they had PsA, a different musculoskeletal disease, or no musculoskeletal disease.
The researchers found 27 patients (17%; 95% confidence interval, 12.3%-21.7%) with previously undiagnosed PsA, 71 with a different musculoskeletal disease, and 61 without musculoskeletal disease. Patients with PsA tended to be male, older, with “worse functional ability,” a similar age at onset of psoriasis, and had similar skin and nail disease severity. The sensitivity for PEST was 0.60 (95% CI, 0.42-0.78) and the specificity was 0.76 (95% CI, 0.69-0.83), while for CONTEST, the sensitivity was 0.53 (95% CI, 0.34-0.72) and the specificity was 0.71 (95% CI, 0.63-0.79). The area under the receiver operating curve confidence intervals for both screening tools were similar, with PEST having an AUC of 0.72 (95% CI, 0.61-0.84) and CONTEST having an AUC of 0.66 (95% CI, 0.54-0.77).
“The relative simplicity of the PEST questionnaire has raised concerns that the tool is not able to detect pure axial forms of the disease,” Dr. Coates and her colleagues wrote. “The CONTEST questionnaire includes items specific to back and neck pain, and so it was hoped it would better detect this subgroup. In this study this is not the case, although the numbers were small and imaging of the spine was not part of the study.”