Central sensitization in psoriatic arthritis: prevalence, clinical correlates, and association with therapeutic refractoriness in an unselected cohort excluding fibromyalgia

Abstract

BACKGROUND: Central sensitization (CS) contributes to persistent pain in psoriatic arthritis (PsA), yet its prevalence, independent predictors, and association with therapeutic refractoriness remain incompletely characterized across disease phenotypes.

OBJECTIVES: To evaluate CS prevalence and clinical correlates in unselected PsA patients excluding fibromyalgia, with emphasis on predictors, multidimensional pain phenotypes, and the association between CS and therapeutic refractoriness.

DESIGN: Cross-sectional observational study.

METHODS: A total of 228 consecutive PsA patients were recruited from April to November 2025 at a single tertiary center. Patients with fibromyalgia (2016 modified ACR criteria, systematically screened) were excluded. CS was assessed using the Central Sensitization Inventory (CSI ⩾40). Disease activity, functionality, pain phenotypes (PAIN DETECT questionnaire (PDQ)), sleep quality (Pittsburgh Sleep Quality Index), depression and anxiety (Hospital Anxiety and Depression Scale), and physical activity (International Physical Activity Questionnaire) and therapeutic refractoriness were systematically measured. Binary and linear regression analyses identified independent predictors of CS.

RESULTS: CS was present in 35.1% of patients. CS was associated with higher disease activity indices (Clinical Disease Activity Index for Psoriatic Arthritis: 14 vs 9.8, = 0.001; Ankylosing Spondylitis Disease Activity Score with C-reactive protein: 4.8 vs 1.8, = 0.007), greater functional disability (Health Assessment Questionnaire-Disability Index: 0.8 vs 0.2, = 0.001), increased neuropathic pain (55.6% vs 8.2%, = 0.001), and notably higher prevalence of therapeutic refractoriness (61.5% vs 6.8%, = 0.003). Independent predictors of CS presence were depression severity (HADS-D: odds ratio (OR) = 1.32, = 0.01), poor sleep quality (Pittsburgh Sleep Quality Index: OR = 1.21, = 0.001), and PDQ (OR = 1.07, = 0.03). Depression, sleep quality, and fatigue explained 47% of CS variance in linear regression.

CONCLUSION: Approximately one-third of unselected PsA patients experience CS, which independently contributes to therapeutic refractoriness despite inflammatory control. Psychosocial factors-particularly sleep dysfunction and depression-emerge as robust predictors of CS. These findings support systematic CS screening in PsA patients with inadequate symptomatic response and highlight the need for integrated biopsychosocial interventions addressing both inflammatory and non-inflammatory pain mechanisms.

Central sensitization (pain hypersensitivity) is common in psoriatic arthritis and linked to poor treatment response, sleep problems, and depression Why was this study done? Psoriatic arthritis (PsA) is a condition that causes joint pain, stiffness, and swelling. Many patients continue to feel significant pain even when medication has successfully treated the swelling and inflammation. This type of pain may be caused by “central sensitization,” a condition where the nervous system becomes overly sensitive and amplifies pain signals. We wanted to find out how common this is in PsA patients, what factors (like sleep or mood) might be related to it, and if it makes treatments seem less effective. What did the researchers do? We studied 228 patients with PsA in a hospital setting. We specifically excluded patients who already had a diagnosis of fibromyalgia to ensure we were looking at pain related to PsA. We used questionnaires to measure central sensitization, pain levels, depression, anxiety, sleep quality, fatigue, and physical activity. We also checked their medical records to see if their treatments were working. What did the researchers find? We found that about one in three patients (35.1%) had central sensitization. These patients had higher pain scores and more difficulty with daily activities, even though their blood tests showed similar levels of inflammation to those without this condition. Importantly, patients with central sensitization were much more likely to be classified as having “difficult-to-treat” disease (refractory), often failing multiple biological medications. We also found that poor sleep, depression, and fatigue were strong predictors of having this type of pain. What do the findings mean? This study suggests that for many patients with PsA, persistent pain is caused by the nervous system rather than active inflammation. Doctors should check for central sensitization before switching strong medications, as these patients might benefit more from treatments that address sleep, mood, and pain sensitivity rather than just more anti-inflammatory drugs.