Patients with psoriatic arthritis have higher levels of FeNO than those with only psoriasis, which may reflect a higher prevalence of a subclinical respiratory involvement.

Background: Psoriatic arthritis (PsA) patients are often affected by numerous comorbidities. However, contrasting results have been reported with regard to the respiratory involvement in PsA patients. The aim of this study was to evaluate the presence of subclinical airway inflammation in non-smoking PsA patients compared to patients with only psoriasis using the fraction of exhaled nitric oxide (FeNO) as an indirect marker of airway inflammation.

Methods: The study included 164 non-smoking psoriatic patients (Psoriasis Area of Severity Index or PASI score > 10): 82 with and 82 without PsA, who underwent FeNO tests at different flow rates (30, 50, 100, 200 mL/s). PsA patients were evaluated with Disease Activity in PSoriatic Arthritis Score (DAPSA). Both study groups were compared in terms of FeNO values and its association with the PASI score. The correlations between the variables were evaluated by means of Pearson's coefficient.

Results: Patient with PsA had higher levels of FeNO than those with psoriasis but without arthritis (at 30 mL/s, 71.09 ± 18.40 ppb vs 66.88 ± 19.12 ppb (NS); at 50 mL/s, 36.61 ± 9.30 ppb vs 30.88 ± 9.73 ppb (p < 0.001); at 100 mL/s, 19.09 ± 4.66 ppb vs 16.63 ± 4.90 ppb (p < 0.001); and at 200 mL/s, 10.88 ± 2.53 ppb vs 9.43 ± 2.55 ppb (p < 0.001), respectively). PASI score correlated to FeNO only in psoriatic patients without arthritis. However, CASPAR index correlated with FeNO (FeNO30: r = 0.81, p < 0.001; FeNO50: r = 0.84, p < 0.001; FeNO100: r = 0.71, p < 0.001; FeNO200: r = 0.58, p < 0.001). DAPSA was also correlated with FeNO to all flows (FeNO30: r = 0.43, p < 0.001; FeNO50: r = 0.33, p < 0.001; FeNO100: r = 0.34, p < 0.001; FeNO200: r = 0.25, p < 0.001).

Conclusions: PsA patients seem to have more commonly subclinical airway inflammation than those with only psoriasis. Further studies are needed to replicate these findings. Key Points • Fraction of exhaled nitric oxide (FeNO) is a useful device to detect and monitor airway inflammation not only in asthma but also in systemic inflammatory diseases such as psoriatic arthritis and psoriasis. • Clinicians should be aware to check respiratory diseases in patients with psoriatic arthritis.