Establishing Central Sensitization-Related Symptom Severity Subgroups: A Multicountry Study Using the Central Sensitization Inventory.

OBJECTIVES: The goal of this study was to identify central sensitization-related symptom severity subgroups in a large multicountry sample composed of patients with chronic pain and pain-free individuals using the Central Sensitization Inventory (CSI). METHODS: A large, pooled international (N = 8 countries) sample of chronic pain patients plus healthy subjects (total N = 2,620) was randomly divided into two subsamples for cross-validation purposes. First, a hierarchical cluster analysis (HCA) was performed using CSI item-level data as clustering variables (test sample; N = 1,312). Second, a latent profile analysis (LPA) was conducted to confirm the optimal number of CSI clusters (validation sample; N = 1,308). Finally, to promote implementation in real-world clinical practice, we built a free online Central Sensitization Inventory Symptom Severity Calculator. RESULTS: In both HCA (N = 1,219 valid cases) and LPA (N = 1,245 valid cases) analyses, a three-cluster and three-profile solution, respectively, emerged as the most statistically optimal and clinically meaningful. Clusters were labeled as follows: (i) Low Level of CS-Related Symptom Severity, (ii) Medium Level of CS-Related Symptom Severity, and (iii) High Level of CS-Related Symptom Severity. CONCLUSIONS: Our results indicated that a three-cluster solution clearly captured the heterogeneity of the CSI data. The calculator might provide an efficient way of classifying subjects into the cluster groups. Future studies should analyze the extent to which the CSI cluster classification correlates with other patient-reported and objective signs and symptoms of CS in patients with chronic pain, their associations with clinical outcomes, health-related costs, biomarkers, (etc.), and responsiveness to treatment.

Cross-cultural adaptation and validity of the Italian version of the Central Sensitization Inventory.

BACKGROUND: Central sensitization (CS) is an important feature in patients with chronic pain. The Central Sensitization Inventory (CSI) was developed with the goal of detecting the patients' symptoms related to CS. OBJECTIVES: This study aimed at cross-culturally adapting the CSI into Italian, and at assessing its structural and construct validity in patients with different chronic pain disorders. DESIGN: Clinimetric study. METHODS: The Italian version of the CSI (CSI-I) was generated following forward and backward translations, expert committee review, and pilot-testing. Patients with pain for ≥3 months were eligible if diagnosed with: low back pain (LBP), temporomandibular disorder (TMD), hand osteoarthritis (HOA), fibromyalgia (FM), or rheumatoid arthritis (RA). Structural validity was assessed with exploratory factor analysis and parallel analysis based on minimum rank factor analysis; construct validity was evaluated by testing ten hypotheses on: 1) expected differences between relevant subgroups, 2) expected correlations with other instruments measuring pain intensity, physical functioning, psychological functioning, headache symptoms, and pain self-efficacy. RESULTS: 220 patients were included: 35% with LBP, 17% with TMD, 19% with HOA, 9% with FM, and 20% with RA. Factor analyses revealed that the CSI-I is a unidimensional instrument. Construct validity was satisfactory since 80% of the hypotheses were met. CONCLUSIONS: The CSI-I was successfully developed and exhibited satisfactory validity in patients with chronic pain. Its reliability, responsiveness and content validity should be investigated in future studies. Until robust evidence indicates a strong relationship between CS and the CSI-I, caution should be adopted in claiming that the CSI-I measures CS.

Primary headaches in patients with temporomandibular disorders: Diagnosis and treatment of central sensitization pain.

OBJECTIVES: Central sensitization (CS) has been found in patients with temporomandibular disorders (TMD), craniofacial pain (CP) and primary headaches, but its clinical implications remain uncertain. The first aim was to provide a synthesis of the current state of knowledge about the link between CS and TMD associated with primary headaches; the second goal was to find methodologies to assess and treat CS in this subgroup of patients. METHODS: A narrative review of the literature was conducted. RESULTS: CS is described in literature as an aggravating factor in patients with TMD-related primary headaches. Further studies are required to support this assertion. CONCLUSIONS: The importance of excluding chronic neuropathic pain and recognizing CS as the main component using a top-down approach to target the best pharmacological and non-pharmacological treatments is evident. Some useful tools to discriminate patients with CS from others have become available, but more research is required to enable an appropriate diagnosis.

Dimensionality and Reliability of the Central Sensitization Inventory in a Pooled Multicountry Sample.

Central sensitization (CS) involves the amplification of neural signaling within the central nervous system, which evokes pain hypersensitivity. The Central Sensitization Inventory (CSI) assesses 25 overlapping health-related symptom dimensions that have been reported to be associated with CS-related disorders. Previous studies have reported satisfactory test-retest reliability and internal consistency, but factor analyses have exhibited conflicting results in different language versions. The purpose of this cross-sectional study was to thoroughly examine the dimensionality and reliability of the CSI, with pooled data from 1,987 individuals, collected in several countries. The principal component analysis suggested that 1 general factor of CS best described the structure. A subsequent confirmatory factor analysis revealed that a bifactor model, which accounted for the covariance among CSI items, with regard to 1 general factor and 4 orthogonal factors, fit the CSI structure better than the unidimensional and the 4-factor models. Additional analyses indicated substantial reliability for the general factor (ie, Cronbach α = .92; ω = .95; and ω hierarchical = .89). Reliability results for the 4 specific factors were considered too low to be used for subscales. The results of this study clearly suggest that only total CSI scores should be used and reported. PERSPECTIVE: As far as we know, this is the first study that has examined the factor structure and reliability of the CSI in a large multicountry sample. The CSI is currently considered the leading self-report measure of CS-related symptoms worldwide.

The Upper Limb Neurodynamic Test 1: intra- and intertester reliability and the effect of several repetitions on pain and resistance.

OBJECTIVE: The aim of this study is to measure the intra- and intertester reliability of the Upper Limb Neurodynamic Test 1 in asymptomatic subjects with respect to onset of pain, submaximal pain (SP), first resistance (R1), and second resistance, and determine the effect of several repetitions of the test. METHODS: Three physiotherapists evaluated the dominant upper arm of 36 asymptomatic adult subjects 5 times with an electrogoniometer. RESULTS: Intratester reliability for R1 was good with an intraclass correlation coefficient (ICC 3,1) ranging from 0.69 to 0.91. Intertester reliability was fair for R1 (0.48, standard error [SE] = 0.14), second resistance (0.62, SE = 0.011), and SP (0.64, SE = 0.09), but good for onset of pain (0.72, SE = 0.011). The ICCs on 5 repetitions for each observer were higher, ranging from 0.51 (R1, SE = 0.066) to 0.76 (SP, SE = 0.049). Using the data from the 2 more expert physiotherapists, almost all ICCs were in the good range. The effect of 5 repetitions was a statistically significant progressive improvement of range on all parameters from the first to the final repetition. CONCLUSIONS: Our results regarding the reliability are in line with other studies on the reliability of manual therapy tests. Moreover, the cumulative effect of repetition suggests that the Upper Limb Neurodynamic Test 1 may warrant investigation as a treatment technique.