Objectives:
Psoriatic arthritis (PsA) is a common but frequently underdiagnosed comorbidity of psoriasis, and early recognition is essential to prevent irreversible joint damage. The Early Arthritis for Psoriatic Patients (EARP) questionnaire is a brief and sensitive screening tool, yet a validated Turkish version has been lacking. This study aimed to linguistically adapt the EARP into Turkish, evaluate its psychometric properties, and determine its diagnostic accuracy for detecting PsA in dermatology practice.

Material and methods:
This multicenter cross-sectional diagnostic study included 119 adults with dermatologist-confirmed psoriasis. Psoriatic arthritis diagnosis was established according to Classification Criteria for Psoriatic Arthritis (CASPAR). The EARP was translated using standardized forward–backward procedures and pilot-tested for cultural relevance. Internal consistency (Cronbach’s a) and test–retest reliability (ICC2,1) were assessed. Diagnostic performance was analyzed through receiver operating characteristic (ROC) curves, yielding area under the curve (AUC), sensitivity, specificity, and predictive values at the optimal cut-off determined by Youden’s index.

Results:
Psoriatic arthritis was diagnosed in 51 participants (42.9%). The Turkish EARP demonstrated high reliability, with Cronbach’s a = 0.86 and ICC2,1 = 0.998. Discriminative validity was strong: mean scores were significantly higher in PsA patients than in non-PsA individuals (6.47 ±1.99 vs. 1.74 ±1.35; p < 0.001). The ROC analysis showed excellent diagnostic accuracy (AUC = 0.971; 95% CI: 0.94–0.99). With the optimal cut-off ≥ 3, sensitivity reached 98.0%, specificity 88.2%, positive predictive value 86.2%, and negative predictive value 98.4%. Most false positives arose in individuals with fibromyalgia-like or mechanical pain symptoms.

Conclusions:
The Turkish EARP is a valid, reliable, and clinically practical instrument for early PsA screening in dermatology settings. Routine implementation may enhance diagnostic timeliness, reduce missed PsA cases, and support efficient referral to rheumatology.