Risk of peripheral neuropathy in patients with psoriasis and psoriatic arthritis. A prospective cohort study

Introduction/Aims: Laboratory and clinical data suggest a link between neurologically mediated inflammation and psoriasis, but the risk and features of peripheral neuropathy in psoriasis or psoriatic arthritis remain unknown. The aim of this exploratory study was to evaluate the risk and to describe the features of peripheral neuropathy in patients with psoriasis and psoriatic arthritis. Methods: One hundred patients with psoriasis and/or psoriatic arthritis and 100 control subjects were consecutively enrolled. Diagnostic confirmation included electrophysiological examination, skin biopsy, and nerve ultrasound for confirmed polyneuropathy. Results: Nine patients were diagnosed with confirmed polyneuropathy, while none of the control subjects had the condition (relative risk [RR] = 19.00, 95% confidence interval [CI] = 1.12–322.11). Specific relative risks for polyneuropathy were 22.09 (95% CI = 1.17–416.43) in psoriasis patients and 18.75 (95% CI = 1.07–327.62) in psoriatic arthritis patients. The observed polyneuropathy in all nine patients was length-dependent, symmetrical, and predominantly sensory, with minimal or no disability. Comorbidities and exposure to therapies known to increase the risk of polyneuropathy were more frequent in psoriasis and/or psoriatic arthritis patients compared to controls (42% vs. 4%, p =.0001). Analyzing data after excluding possible contributory causes, the risk of polyneuropathy in patients with psoriasis and/or psoriatic arthritis was not significant. Discussion: Psoriasis and psoriatic arthritis appear to be associated with an increased risk of polyneuropathy. This increased risk seems to be linked to the higher prevalence of contributing factors for polyneuropathy, rather than a direct increase in neuropathy risk specifically related to psoriasis and psoriatic arthritis.