An observational study in Fibromyalgia, Chronic Pain and Nociplastic Pain, sponsored by University of Bari. Recruiting at 5 sites in Italy. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-11.
Sponsored by University of Bari · Observational
The Emotional Allodynia Questionnaire (AEQ) is an 11-item self-report instrument that measures disproportionate emotional reactivity to low-intensity interpersonal cues(perceived unresponsiveness, exclusion, loss of reciprocity), a pattern termed emotional allodynia. It was preliminarily validated in a single-center fibromyalgia sample. PEARL (validation phase) is a multicenter, prospective, observational psychometric validation study that (1) replicates the internal structure and convergent validity of the AEQ in an independent fibromyalgia sample, (2) tests its known-groups (discriminative) accuracy in separating fibromyalgia from non-fibromyalgia chronic pain of defined nociceptive or neuropathic origin, expressed as the area under the ROC curve (AUC), and (3) assesses test-retest reliability. There is no intervention.
Design: multicenter (Italian tertiary pain centers), observational, case-control psychometric validation study. Cases are adults with fibromyalgia (2016 ACR criteria); controls are adults with chronic non-cancer pain of defined nociceptive or neuropathic origin who do not meet fibromyalgia criteria. Group membership reflects clinical diagnosis and is not assigned by the investigators.
Assessment: the primary assessment is cross-sectional at baseline (T0). All enrolled participants (cases and controls) are reassessed once for test-retest reliability (T1) at approximately 40 days (plus or minus 10 days). The battery comprises the AEQ, Central Sensitization Inventory (CSI), Pain Catastrophizing Scale (PCS), Beck Depression Inventory-II (BDI-II), State-Trait Anxiety Inventory (STAI-Y forms 1 and 2), Difficulties in Emotion Regulation Scale (DERS), and a Visual Analog Scale (VAS) for pain. Questionnaires are self-administered on paper with physician-verified completeness at the point of care, then transcribed into a secure online data-collection form.
Sample size: two targets. The fibromyalgia cohort comprises 274 patients (137 per depression stratum, sized for internal consistency and depression-stratified estimation; PASS 2024 v24.0.5). For the known-groups discriminative analysis, 151 evaluable non-fibromyalgia chronic pain controls are required, sized on precision for a 95% confidence interval of width 0.10 around an anticipated AUC of 0.80 (Hanley-McNeil standard-error method, PASS 2024 v24.0.9); the 97-per-group level is the minimum to test an AUC of 0.80 against a null of 0.70 (two-sided alpha 0.05, 80% power; Hanley-McNeil / Obuchowski-McClish).
Primary analysis: ROC analysis with the AEQ total score as classifier and diagnostic group as the reference (fibromyalgia = positive); the AUC is tested against 0.70 with its 95% CI. A covariate-adjusted logistic-regression sensitivity analysis (age, sex, depressive comorbidity) and a center-adjusted analysis are pre-specified. Secondary analyses include convergent and discriminant validity, exploratory and confirmatory factor analysis, test-retest ICC, AEQ-CSI median-split phenotyping (Resilient, Emotional Allodynia, Central Sensitization, Mixed), a pre-specified depression-stratified analysis, and exploratory unsupervised clustering.
Protocol amendment (version 2.1, 5 September 2026). The statistical analysis plan is revised as follows: (1) latent profile analysis on the continuous scores replaces latent class analysis as the primary model-based method for unsupervised phenotyping; (2) discriminant validity by the Fornell-Larcker criterion is examined against the Pain Catastrophizing Scale in addition to the DERS; (3) the AUC is additionally reported, descriptively, within the nociceptive and neuropathic subgroups of the control cohort. Eligibility, procedures, participant burden and consent are unchanged.
1,243 studies on the registry are indexed under Fibromyalgia; 256 are open to participants now.
This study's planned enrollment of 425 is above the median of 100 across 279 observational studies indexed under Fibromyalgia.
Browse Fibromyalgia studies →University of Bari is the lead sponsor of 76 studies on the registry; 12 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Adults attending Italian tertiary pain outpatient services. Cases are identified from fibromyalgia services; controls are identified among patients attending the same services for chronic non-cancer pain of defined nociceptive or neuropathic origin. Consecutive eligible patients are considered for enrollment.
CASES (fibromyalgia)
Inclusion Criteria:
Exclusion Criteria:
CONTROLS (non-fibromyalgia chronic pain)
Inclusion Criteria:
Exclusion Criteria (parallel to cases):
Note: ongoing pharmacological treatment for pain or mental health is not an exclusion criterion in either group; Major Depressive Disorder and Panic Disorder are recorded at baseline and used in covariate-adjusted and stratified analyses.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adults with fibromyalgia diagnosed per the 2016 ACR criteria.
Adults with chronic non-cancer pain of defined nociceptive or neuropathic origin who do not meet the 2016 ACR criteria for fibromyalgia.
Internal consistency of the Emotional Allodynia Questionnaire (AEQ) in fibromyalgia cases
Internal consistency reliability of the AEQ, an 11-item self-report questionnaire (total score range 0-44), in fibromyalgia cases, assessed using Cronbach's alpha and McDonald's omega, each reported with 95% confidence intervals.
Time frame: Baseline (T0)
Factorial structure of the Emotional Allodynia Questionnaire (AEQ)
Latent factor structure of the 11-item AEQ self-report questionnaire, assessed by exploratory factor analysis and a single-factor confirmatory factor analysis (CFA). Reported as CFA model fit indices: comparative fit index (CFI), Tucker-Lewis index (TLI), root mean square error of approximation (RMSEA), and standardized root mean square residual (SRMR).
Time frame: Baseline (T0)
Known-groups discriminative accuracy of the AEQ (AUC)
Discriminative accuracy of the AEQ total score (11-item self-report questionnaire) in distinguishing fibromyalgia cases from non-fibromyalgia chronic pain controls, reported as the area under the receiver operating characteristic (ROC) curve (AUC, range 0-1) with 95% confidence interval, tested against a null value of 0.70.
Time frame: Baseline (T0)
Convergent validity of the Emotional Allodynia Questionnaire (AEQ)
Convergent validity reported as Spearman rank correlation coefficients (rho, range -1 to 1) between the AEQ total score and the Central Sensitization Inventory (CSI), Pain Catastrophizing Scale (PCS), Beck Depression Inventory-II (BDI-II), State-Trait Anxiety Inventory (STAI-Y), and Difficulties in Emotion Regulation Scale (DERS).
Time frame: Baseline (T0)
Discriminant validity of the Emotional Allodynia Questionnaire (AEQ) versus the DERS
Discriminant validity of the AEQ relative to the DERS, reported as (a) a chi-square statistic for dissociation across AEQ and DERS median-split groups and (b) the Fornell-Larcker criterion, comparing the AEQ's average variance extracted (AVE) with the squared AEQ-DERS correlation (proportions, range 0-1).
Time frame: Baseline (T0)
Test-retest reliability of the Emotional Allodynia Questionnaire (AEQ) total score
Test-retest reliability of the AEQ total score (11-item self-report questionnaire) in the full enrolled sample (cases and controls), reported as the intraclass correlation coefficient (ICC, range 0-1; two-way mixed-effects model, absolute agreement, single rater) with 95% confidence interval.
Time frame: Baseline (T0) and retest at approximately 40 days (plus or minus 10 days)
AEQ score distribution across AEQ-CSI median-split phenotypes
Distribution of the AEQ total score (points, range 0-44) across the four AEQ-CSI median-split phenotypes (Resilient, Emotional Allodynia, Central Sensitization, Mixed), and between-phenotype differences on validated measures not used to define them (PCS, BDI-II, STAI-Y, DERS total scores)
Time frame: Baseline (T0)
Floor and ceiling effects of the Emotional Allodynia Questionnaire (AEQ)
Reported as the percentage of participants (%) scoring at the minimum (floor) and at the maximum (ceiling) of the AEQ total score (11-item self-report questionnaire, total score range 0-44).
Time frame: Baseline (T0)
Depression-stratified internal consistency and convergent validity of the AEQ
Computed separately within fibromyalgia cases stratified by presence vs. absence of major depressive disorder, reported as Cronbach's alpha (range 0-1) and Spearman correlation coefficients (rho, range -1 to 1) of the AEQ total score with CSI, PCS, BDI-II, STAI-Y, and DERS.
Time frame: Baseline (T0)
Concordance between AEQ-CSI phenotypes and data-driven clusters
Agreement between the theory-driven AEQ-CSI median-split phenotypes (Resilient, Emotional Allodynia, Central Sensitization, Mixed) and data-driven clusters from k-means, hierarchical clustering (Ward's method), and latent class analysis (LCA), reported as the Adjusted Rand Index (range -1 to 1).
Time frame: Baseline (T0)
Plan to share: No — Individual participant data (IPD) will not be shared publicly. Under Italian data protection regulations and the EU General Data Protection Regulation (GDPR), participant-level data from this study cannot be made publicly available. The working dataset is pseudonymized and held on secure institutional systems. De-identified data supporting the main findings may be made available from the corresponding author upon reasonable request, subject to a data-sharing agreement and compliance with applicable data-protection requirements.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
University of Bari