title: Specificity and sensitivity of objective tests to detect possible malingering in fibromyalgia: a case-control study in 211 Spanish patients.
abstract: OBJECTIVE
  To characterise patients diagnosed with fibromyalgia (FM) who present a clinical profile suggestive of simulation.
  
  
  METHODS
  Observational case-control study of 218 patients who met the classification criteria for FM. The profile supporting simulation was based on the proposed criteria for evaluating disability related to the simulation of pain.
  
  
  RESULTS
  Compared with controls (n=105), patients with suspected simulation of FM (n=106) had a higher mean age (52.5 vs. 49.2 years, p=0.003), a higher frequency of primary education (88.7% vs. 58.1%; p<0.001), a higher percentage of separated/widowed persons (33.9% vs. 8.6%, p<0.001), a higher frequency of psychiatric disorders (100% vs. 67.6%, p<0.001), a higher mean number of positive 'control' tender points (4.5 vs. 1.3, p<0.001), a higher mean FIQ questionnaire score (89.8 vs. 68.8, p<0.001) and a lower mean LHS questionnaire score (41.0 vs. 59.9, p<0.001). Patients with suspected simulation were able to walk a shorter distance in the 6-minute walk test than controls (231.0 vs. 356.3 metres, p<0.001), while the appearance of allodynia was achieved with a significantly lower mmHg pressure (159.8 vs. 229.9 mm Hg, p<0.001).
  
  
  CONCLUSIONS
  Some physical/functional tests, together with the administration of specific questionnaires, may identify a subgroup of patients with FM with a profile consistent with simulation or malingering; these patients have a differentiated demographic and psychiatric profile in comparison with FM patients without a profile of simulation.
authors.affiliation: Rheumatology Department, Hospital 9 de Octubre, Valencia, Spain. rbelenguer@gmail.com.
authors.forename: Rafael
authors.initials: R
authors.lastname: Belenguer-Prieto
authors.forename: Emma M
authors.initials: EM
authors.lastname: Morales-Espinoza
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Martín-González
authors.forename: Pilar
authors.initials: P
authors.lastname: Brito-Zerón
authors.forename: Jose F
authors.initials: JF
authors.lastname: Pastor-Oliver
authors.forename: Belchin
authors.initials: B
authors.lastname: Kostov
authors.forename: David
authors.initials: D
authors.lastname: Buss
authors.forename: Cayetano
authors.initials: C
authors.lastname: Gómez-Gálvez
authors.forename: Antonio
authors.initials: A
authors.lastname: Salazar-Cifre
authors.forename: Antoni
authors.initials: A
authors.lastname: Sisó-Almirall
authors.forename: Manuel
authors.initials: M
authors.lastname: Ramos-Casals
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D004185:Disability Evaluation; D005080:Exercise Test; D005260:Female; D005356:Fibromyalgia / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D015438:Health Behavior; D006801:Humans; D006930:Hyperalgesia / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D008297:Male; D008306:Malingering / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D008875:Middle Aged; D010147:Pain Measurement; D058748:Pain Perception; D017288:Pain Threshold; D010808:Physical Examination; D011237:Predictive Value of Tests; D012372:ROC Curve; D012720:Severity of Illness Index; D013030:Spain; D011795:Surveys and Questionnaires