A new integral enthesial-comorbididity index of psoriatic arthritis activity

Aim. To develop an integral index of psoriatic arthritis (PsA) activity.

Materials and methods. 117 patients with PsA (M/F – 63/54) were included. Patients’ age 44±11 years, psoriasis (Ps) duration – 213±153 months, PsA duration – 73.4±78.5 months. Patients underwent standard clinical examination of PsA activity: tender (out of 68) and swollen (out of 66) joint counts (TJC, SJC), LEI, tenderness of the plantar fascia (PF), skin lesion severity (BSA), presence of nail Ps, body mass index (BMI), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), DAPSA, FACIT-F. Parametric and nonparametric statistic methods, correlation and ROC analysis were used.

Results. Mean DAPSA was 38±21, TJC – 14.2±10.6, SJC – 10.6±8.3, ESR – 30.5±29.5 mm/h, CRP – 23.3±29 mg/l, LEI – 1.2±1.5, FACIT-F – 32±11, BMI – 27.4±6.2 kg/m². The following significant positive correlations were revealed: between DAPSA and BMI, patients’ age, ESR, PsA and Ps duration, TJC, SJC, LEI, presence of PF enthesitis, skin lesion severity, presence of nail Ps. A negative correlation between FACIT-F and male sex was found. Based on the predictive model of parameters, the Entesial-Comorbid Index of PsA (ECIPsA) was created: 3.81×LEI+13.72×PF+0.54×Age-0.25×FACIT-F+7.36×BSA+7.94×PsA duration+5.5×Nail Ps+0.32×BMI-3.52, namely LEI – Leeds Enthesial Index; PF – pain in the PF; patient’s age; FACIT-F – fatigue scale; BSA<3%=0, ≥3%=1; PsA duration≤2 years=0, >2 years=1; presence of nail Ps=1, absence=0; ECIPsA≥28 corresponds with high PsA activity according to DAPSA≥28. ROC analysis of sensitivity and specificity of the prognostic model demonstrated high correctness of the index: the area under the ROC curve was 0.768, 95% confidence interval (0.624–0.913).

Conclusion. The new PsA activity index corresponds to the existing ones and takes into consideration the clinical heterogeneity and comorbidity of the disease.