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Prevalence of Functional Gastrointestinal Disorders in Patients With Fibromyalgia and the Role of Psychologic Distress

Published:December 15, 2008DOI:https://doi.org/10.1016/j.cgh.2008.12.005

      Background & Aims

      Fibromyalgia is a rheumatologic disorder associated with somatic and psychologic conditions. Although fibromyalgia is associated with irritable bowel syndrome, its relationship with other functional gastrointestinal disorders (FGID) is unclear. We evaluated the prevalence of FGID in patients with fibromyalgia and the role of psychologic factors in this relationship.

      Methods

      From a Spanish population, 100 patients with fibromyalgia and 100 matched controls completed the Rome II Integrative Questionnaire to assess the prevalence of FGID and the Symptom Checklist-90 Revised (SCL-90R) to evaluate psychologic distress. Patients completed the Fibromyalgia Impact Questionnaire to evaluate the overall impact of fibromyalgia and controls filled out the Chronic Widespread Pain Questionnaire to detect potential cases of fibromyalgia.

      Results

      Ninety-three percent of the total study population was female, with a mean age of 50 years. We identified 6 cases of widespread pain among controls. The average Fibromyalgia Impact Questionnaire score for patients was 67.28 ± 14.25. All gastrointestinal symptoms except for vomiting were more frequent in patients. Ninety-eight percent of patients with fibromyalgia had at least one FGID, compared with only 39% of controls. Fibromyalgia was correlated most highly with irritable bowel syndrome. Patients presented with significantly higher scores of psychologic distress than controls, especially those with fecal incontinence.

      Conclusions

      There is a prevalence of FGID in patients with fibromyalgia and a wider distribution of such symptoms along the gastrointestinal tract compared with controls. We propose that an increased degree of psychologic distress in these patients predisposes them to FGID, especially significant for anorectal syndromes.

      Abbreviations used in this paper:

      FGID (functional gastrointestinal disorder), FIQ (Fibromyalgia Impact Questionnaire), FM (fibromyalgia), GSI (global severity index), IBS (irritable bowel syndrome), PSDI (positive symptom distress index), PST (positive symptom total), SCL-90R (Symptom Checklist-90 Revised)
      Chronic diffuse musculoskeletal pain syndromes are common, affecting 4% to 13% of the general population.
      • Wolfe F.
      • Ross K.
      • Anderson J.
      • et al.
      The prevalence and characteristics of fibromyalgia in the general population.
      • Croft P.
      • Rigby A.S.
      • Boswell R.
      • et al.
      The prevalence of chronic widespread pain in the general population.
      • Lindell L.
      • Bergman S.
      • Petersson I.F.
      • et al.
      Prevalence of fibromyalgia and chronic widespread pain.
      Fibromyalgia (FM) is a specific disorder characterized by chronic widespread pain and tender points at 11 of 18 musculoskeletal sites but otherwise normal physical examination.
      • Wolfe F.
      • Smythe H.A.
      • Yunus M.B.
      • et al.
      The American College of Rheumatology 1990 criteria for the classification of fibromyalgia Report of the multicenter criteria committee.
      The prevalence of FM in the community is around 2%, increasing with age and female sex.
      • Wolfe F.
      • Ross K.
      • Anderson J.
      • et al.
      The prevalence and characteristics of fibromyalgia in the general population.
      • Carmona L.
      • Ballina J.
      • Gabriel R.
      • et al.
      EPISER Study Group
      The burden of musculoskeletal diseases in the general population of Spain: results from a national survey.
      The pathogenesis of FM still is uncertain; although some investigators have suggested that FM could be caused by a dysfunction in central monoaminergic neurotransmission that in part could be determined genetically,
      • Gursoy S.
      Absence of association of the serotonin gene transporter gene polymorphism with the mental health subset of fibromyalgia patients.
      • Cohen H.
      • Buskila D.
      • Neumann L.
      • et al.
      Confirmation of an association between FMS and the serotonin transporter promoter region (5-HTTLPR) polymorphism and relationship to anxiety-related personality traits.
      • Offenbaecher M.
      • Bondy B.
      • de Jonge S.
      • et al.
      Possible association of fibromyalgia with a polymorphism in the serotonin transporter gene regulatory region.
      others have suggested a psychosocial explanation for its origin, considering FM as a depression spectrum disorder based on a stress vulnerability model.
      • Raphael K.G.
      • Janal M.N.
      • Nayak S.
      • et al.
      Familial aggregation of depression in fibromyalgia: a community-based test of alternate hypothesis.
      However, it is possible that both psychologic as well as biological factors could be implied, leading to the hypothesis of a biopsychosocial pathogenetic model.
      • Ferrari R.
      The biopsychosocial model: a tool for rheumatologists.
      Symptoms of other unexplained clinical conditions such as bowel disturbances or chronic fatigue frequently overlap in patients with FM, in such a way that these symptoms have been considered by some experts as auxiliary in the diagnosis of FM.
      • Wolfe F.
      • Smythe H.A.
      • Yunus M.B.
      • et al.
      The American College of Rheumatology 1990 criteria for the classification of fibromyalgia Report of the multicenter criteria committee.
      Moreover, the overlap of FM with some unexplained clinical conditions such as irritable bowel syndrome (IBS), migraines, chronic fatigue syndrome, cataplexy, multiple chemical sensitivities, and mood disorders,
      • Aaron L.A.
      • Buchwald D.
      A review of the evidence for overlap among unexplained clinical conditions.
      • Hudson J.L.
      • Goldenberg D.L.
      • Pope H.G.
      • et al.
      Comorbidity of fibromyalgia with medical and psychiatric disorders.
      has led some researchers to suggest that certain diseases could fall into clusters linked by common etiologic factors. These entities have been called affective spectrum disorder, dysfunctional spectrum syndrome, functional somatic disorders, or central sensitization syndromes.
      • Yunus M.B.
      Psychological aspects of fibromyalgia syndrome: a component of the dysfunctional spectrum syndrome.
      • Wessely S.
      • Nimnuan C.
      • Sharpe M.
      Functional somatic syndromes: one or many?.
      • Yunus M.B.
      Role of central sensitization in symptoms beyond muscle pain, and the evaluation of a patient with widespread pain.
      • Hudson J.I.
      • Mangweth B.
      • Pope H.G.
      • et al.
      Family study of affective spectrum disorder.
      • Arnold L.M.
      • Hudson J.I.
      • Hess E.V.
      • et al.
      Family study of fibromyalgia.
      • Hudson J.I.
      • Arnold L.M.
      • Keck P.E.
      • et al.
      Family study of fibromyalgia and affective spectrum disorder.
      Functional gastrointestinal disorders (FGID) represent a heterogeneous group of gastrointestinal diseases characterized by the absence of any structural or biochemistry abnormality that could explain symptoms
      • Longstreet G.F.
      • Thompson W.G.
      • Chey W.D.
      • et al.
      Functional bowel disorders.
      ; they are defined by established criteria according to a consensus from experts.
      • Thompson W.G.
      The road to Rome.
      The etiology of FGID also is unclear; although as well as in FM, genetic, biological, and psychosocial factors
      • Saito Y.A.
      • Petersen G.M.
      • Locke G.R.
      • et al.
      The genetics of irritable bowel syndrome.
      • Whitehead W.E.
      • Palsson O.
      • Jones K.R.
      Systematic review of the comorbidity of irritable bowel syndrome with other disorders: what are the causes and implications?.
      • Levy R.L.
      • Olden K.W.
      • Naliboff B.D.
      • et al.
      Psychosocial aspects of the functional gastrointestinal disorders.
      have been implied.
      The association between FM and FGID is thought to be strong according to studies performed with IBS, which is the most representative and best characterized of all FGIDs,
      • Whitehead W.E.
      • Palsson O.
      • Jones K.R.
      Systematic review of the comorbidity of irritable bowel syndrome with other disorders: what are the causes and implications?.
      but currently there is a lack of studies evaluating the association among FM and other FGIDs.
      • Chang L.
      The association of functional gastrointestinal disorders and fibromyalgia.
      The prevalence of FM in IBS patients is high, ranging from 28% to 65%.
      • Barton A.
      • Pal B.
      • Whorwell P.J.
      • et al.
      Increased prevalence of sicca complex and fibromyalgia in patients with irritable bowel syndrome.
      • Veale D.
      • Kavanagh G.
      • Fielding J.F.
      • et al.
      Primary fibromyalgia and the irritable bowel syndrome: different expressions of a common pathogenetic process.
      Conversely, 32% to 80% of FM patients suffered from IBS.
      • Sperber A.D.
      • Atzmon Y.
      • Neumann L.
      • et al.
      Fibromyalgia in the irritable bowel syndrome: studies of prevalence and clinical implications.
      • Kurland J.E.
      • Coyle W.J.
      • Winkler A.
      • et al.
      Prevalence of irritable bowel syndrome and depression in fibromyalgia.
      In addition to the fact that psychologic factors can be involved in the pathogenesis of both FM and FGID,
      • Raphael K.G.
      • Janal M.N.
      • Nayak S.
      • et al.
      Familial aggregation of depression in fibromyalgia: a community-based test of alternate hypothesis.
      • Alander T.
      • Svärdsudd K.
      • Johansson S.E.
      • et al.
      Psychological illness is commonly associated with functional gastrointestinal disorders and is important to consider during patient consultation: a population-based study.
      it has been reported that patients with a coexistence of FM and IBS have more sleep disturbances, decreased well being, lower sense of coherence, increased psychologic distress, poorer coping skills, and more anxiety than those presenting with a single condition.
      • Lubrano E.
      • Iovino P.
      • Tremolaterra F.
      • et al.
      Fibromyalgia in patients with irritable bowel syndrome An association with the severity of the intestinal disorder.
      Whether psychologic distress is a cause, a consequence, or an associated factor in these unexplained clinical conditions remains controversial.
      Our study aimed to evaluate the prevalence of FGIDs in patients diagnosed with FM, as well as assess the potential role that psychologic features play in this relationship.

      Methods

       Population

      Patients were selected randomly from the Madrilian Association of Patients with Fibromyalgia, which requires a medical diagnosis of FM performed by a rheumatologist according to the American College of Rheumatology (ACR) criteria
      • Wolfe F.
      • Smythe H.A.
      • Yunus M.B.
      • et al.
      The American College of Rheumatology 1990 criteria for the classification of fibromyalgia Report of the multicenter criteria committee.
      to be enrolled. Controls were selected randomly from a list of the Madrid electoral census and matched by age and sex with patients.
      All controls selected were first contacted by telephone and those who agreed to participate completed the questionnaires over the telephone; meanwhile patients completed the questionnaires in the Association's office under the supervision of one of the researchers.
      The following questionnaires were completed.

       Rome II Integrative Questionnaire for Functional Gastrointestinal Disorders

      To evaluate the prevalence of gastrointestinal symptoms and FGID in patients and controls, given that this questionnaire was available only in English, we previously adapted it into Spanish through a process of translation and back-translation.
      The translation procedure was as follows: the original Rome II Questionnaire
      was translated into Spanish by 2 independent gastroenterologists (native Spanish speakers) and then translated back into English by an independent official translator (native English speaker). The 2 translations then were compared and a final version was drawn up after agreement of all participants.
      Gastrointestinal symptoms were considered relevant when patients reported them more than 25% of the time. FGIDs were diagnosed according to the Rome II criteria when the required symptoms were present for at least 12 weeks in the past 12 months. However, for survey purposes it was accepted that symptoms might be present only in the previous 3 months for certain categories (functional gastroduodenal and functional bowel disorders).
      Symptoms were able to overlap among different disorders, and more than one FGID can coexist in the same individual. However, there were some exceptions to this rule: functional heartburn and functional dysphagia are mutually exclusive; IBS and functional dyspepsia have to be excluded to diagnosis functional abdominal bloating; and functional abdominal pain and IBS have to be excluded to diagnose functional constipation.

       Symptom Checklist-90 Revised

      We used the Spanish version of the validated Symptom Checklist-90 Revised (SCL-90R) instrument to evaluate psychologic distress in patients and controls.
      • Martínez Azumendi O.
      • Fernández Gómez C.
      • Beitia Fernández M.
      Factorial variance of the SCL-90-R in a Spanish outpatient psychiatric sample.
      It measures 9 primary symptom dimensions (somatization, obsessive compulsive, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, and psychoticism) and their intensity at a specific point in time through 3 global indices: global severity index (GSI), positive symptom distress index (PSDI), and positive symptom total. The symptom distress scores were transformed to T-scores based on normal male and female scores; considering a score of 50 as a reference standard, 60 as a higher risk of psychopathology, and a score of 70 or higher as clinically abnormal.
      • Derogatis L.R.
      • Rickels K.
      • Rock A.F.
      The SCL-90 and the MMPI: a step in the validation of a new self reported scale.

       Fibromyalgia Impact Questionnaire

      To evaluate the overall impact of FM over different dimensions of the patient's life, we used a version of the questionnaire designed by Burckhardt et al,
      • Burckhardt C.S.
      • Clark S.R.
      • Bennett R.M.
      The fibromyalgia impact questionnaire: development and validation.
      adapted and validated to use in Spanish patients by Rivera and González.
      • Rivera J.
      • González T.
      The Fibromyalgia Impact Questionnaire: a validated Spanish version to assess the health status in women with fibromyalgia.
      The Fibromyalgia Impact Questionnaire (FIQ) is a 10-item questionnaire, with a maximum score of 10 per item and a maximum global score of 100. As a rule, the average FM patient scores about 50; severely afflicted patients usually score 70 or higher.
      • Bennett R.
      The Fibromyalgia Impact Questionnaire (FIQ): a review of its development, current version, operating characteristics and uses.

       Chronic Widespread Pain Questionnaire

      To detect potential cases of FM previously not diagnosed among controls we used the Spanish version
      • Carmona L.
      • Ballina J.
      • Gabriel R.
      • et al.
      EPISER Study Group
      The burden of musculoskeletal diseases in the general population of Spain: results from a national survey.
      of the Chronic Widespread Pain survey adapted from Wolfe et al.
      • Wolfe F.
      • Ross K.
      • Anderson J.
      • et al.
      The prevalence and characteristics of fibromyalgia in the general population.
      Chronic widespread pain was defined as the presence of pain in the upper body, lower body, axial skeletal, and left and right sides during at least 3 months, without any history of lesion or trauma that could explain the symptoms.
      • Carmona L.
      • Ballina J.
      • Gabriel R.
      • et al.
      EPISER Study Group
      The burden of musculoskeletal diseases in the general population of Spain: results from a national survey.

       Statistics

      The sample size was estimated in 99 subjects per group to detect a 10% difference in the prevalence of each FGID between cases and controls by using a bilateral contrast test with a β value of .1 and an α value of .05.
      Prevalence was described as a percentage of the total sample with a 95% confidence interval. Numeric variables were summarized with the sample mean and standard deviation, except as otherwise stated. Categoric variables were summarized with numbers and percentages. The chi-squared test was used to compare proportions among patients and controls. The relationship between psychologic distress and FGIDs in patients with fibromyalgia was evaluated by a logistic regression test adjusted by age, sex, FIQ score, and education. Statistical significance was set at the 5% level.

       Ethics

      This study was approved by the Hospital Clínico San Carlos Ethic Research Committee. All participants were informed about the nature of the study and provided their consent before inclusion.

      Results

      We included 100 patients and 100 controls matched by age and sex. Controls showed a slightly higher educational level than cases, but no significant differences on other characteristics (Table 1). We identified 6 cases of widespread musculoskeletal pain among controls (6%; 95% confidence interval, 1.5–10.6). Exclusion of these subjects from the analysis did not modify results. The overall impact of FM in a patient's life as assessed by the FIQ was 67.28 ± 14.25 among patients.
      Table 1Demographics of Study Participants
      FeaturesPatients (n = 100)Controls (n = 100)P
      Mean age ± SD
      Matching variable.
      50.5 ± 9.650.3 ± 11.4NS
      Females
      Matching variable.
      9393NS
      Marital statusNS
       Single1114
       Married6364
       Divorced2322
      Level of education/literacy<.001
       School/basic2340
       High school/middle3443
       College or university/high4115
      SD, standard deviation.
      a Matching variable.

       Prevalence of Gastrointestinal Symptoms

      As shown in Table 2, all gastrointestinal symptoms, except for vomiting, were significantly more frequent in patients than controls.
      Table 2Prevalence of Gastrointestinal Symptoms in Patients Compared With Controls
      LocationSymptomsControls prevalence, % (95% CI)Patients prevalence, % (95% CI)
      EsophagealGlobus4 (0.2–7.8)55 (45.2–64.8)
      P < .05.
      Dysphagia2 (0–4.7)35 (25.6–44.4)
      P < .05.
      Rumination3 (0–6.3)24 (15.6–32.4)
      P < .05.
      Heartburn8 (2.7–13.3)40 (30.4–49.6)
      P < .05.
      Chest pain8 (2.7–13.3)55 (45.2–64.8)
      P < .05.
      GastroduodenalAerophagia5 (0.7–9.3)34 (24.7–43.3)
      P < .05.
      Early satiety10 (4.1–15.9)41 (31.4–50.6)
      P < .05.
      Postprandial fullness12 (5.6–18.4)68 (58.9–77.1)
      P < .05.
      Nausea7 (2–12)49 (39.2–58.8)
      P < .05.
      Vomiting4 (0.2–7.8)8 (2.7–13.3)
      BowelAbdominal pain8 (2.7–13.3)75 (66.5–83.5)
      P < .05.
      Constipation14 (7.2–20.8)56 (46.3–65.7)
      P < .05.
      Bloating14 (7.2–20.8)88 (81.6–94.4)
      P < .05.
      Diarrhea4 (0.2–7.8)35 (25.6–44.4)
      P < .05.
      AnorectalAnorectal pain6 (1.3–10.7)43 (33.3–52.7)
      P < .05.
      Incontinence32 (22.9–41.1)56 (46.3–65.7)
      P < .05.
      CI, confidence interval.
      a P < .05.
      Ninety-eight patients versus 49 controls reported at least one gastrointestinal symptom; the number of symptoms per subject was significantly higher in patients with FM than in controls (11.5 ± 4.5 vs 4.2 ± 4.4). In addition, up to 52% of patients presented with symptoms related to the 4 gastrointestinal segments (esophageal, gastroduodenal, bowel, and anorectal) compared with 15% of subjects in the control group.

       Prevalence of Symptom Complexes Fulfilling Criteria of Functional Gastrointestinal Disorders

      Ninety-eight percent of patients with FM presented with at least one FGID, compared with 39% of controls. Among all FGIDs the strongest association with FM was found with IBS, followed by functional bloating and functional fecal incontinence. Table 3 details the prevalence of all FGIDs in patients and controls.
      Table 3Prevalence of FGIDs in Patients With FM Compared With Controls
      LocationFunctional disorderControls prevalence, % (95% CI)Patients prevalence, % (95% CI)
      EsophagealGlobus03 (0–6.3)
      Rumination syndrome08 (2.7–13.3)
      P < .001.
      Functional chest pain1 (0–3)3 (0–6.3)
      Functional dysphagia06 (1.3–10.7)
      P < .001.
      Functional heartburn4 (0.2–7.8)9 (3.4–14.6)
      Any disorder5 (0.7–9.3)27 (18.3–35.7)
      P < .05.
      GastroduodenalFunctional dyspepsia3 (0–6.3)21 (13–29)
      P < .001.
      Aerophagia2 (0–4.7)17 (9.6–24.4)
      P < .001.
      Functional vomiting1 (0–3)0
      Any disorder5 (0.7–9.3)34 (24.7–43.3)
      P < .001.
      BowelIBS3 (0–6.3)39 (29.4–48.6)
      P < .001.
      Functional bloating12 (5.6–18.4)34 (24.7–43.3)
      P < .001.
      Functional constipation5 (0.7–9.3)15 (8–22)
      P < .05.
      Functional diarrhea02 (0–4.7)
      Any disorder18 (10.5–25.5)82 (74.5–89.5)
      P < .001.
      Abdominal painFunctional abdominal pain04 (0.2–7.8)
      Unspecified functional pain1 (0–3)19 (11.3–26.7)
      P < .001.
      Gallbladder dysfunction1 (0–3)2 (0–4.7)
      Biliary painSphincter of Oddi dysfunction00
      AnorectalFunctional incontinence25 (16.5–33.5)45 (35.2–54.8)
      P < .001.
      Levator ani syndrome4 (0.2–7.8)23 (14.7–31.3)
      P < .001.
      Proctalgia fugax1 (0–3)10 (4.1–15.9)
      P < .05.
      Pelvic floor dysfunction4 (0.2–7.8)7 (2–12)
      Any disorder28 (19.2–36.8)59 (49.4–68.6)
      P < .001.
      CI, confidence interval.
      a P < .001.
      b P < .05.

       Psychologic Distress

      Patients presented with significantly higher scores in the GSI than controls, driven by a higher intensity of symptoms (PSDI), although the total numbers of self-reported symptoms (positive symptom total) were similar among both groups. In addition, patients with FM present with significantly higher levels of somatization, obsessivity, depression, anxiety, and interpersonal sensitivity than controls (Table 4).
      Table 4Comparison of SCL-90R T-Scores Between Patients and Controls
      PatientsControlsP
      Somatization71.41 ± 4.8855.13 ± 7.90<.001
      Obsessive69.17 ± 6.4055.27 ± 9.76<.001
      Interpersonal sensitivity61.03 ± 10.5058.00 ± 10.67<.05
      Depression63.68 ± 8.7352.61 ± 9.88<.001
      Anxiety62.96 ± 9.2755.62 ± 10.10<.001
      Hostility56.35 ± 9.5656.51 ± 9.89NS
      Phobia57.50 ± 13.4057.85 ± 13.11NS
      Paranoia57.00 ± 12.0857.62 ± 10.77NS
      Psychoticism61.80 ± 10.3261.81 ± 12.63NS
      GSI66.99 ± 6.9957.49 ± 11.06<.001
      PST66.49 ± 7.8263.67 ± 12.36NS
      PSDI61.00 ± 7.0544.64 ± 8.94<.001
      NS, not significant.
      Among patients with FM, higher scores of GSI, PSDI, and positive symptom total were found in those with functional fecal incontinence; patients with both FM and IBS present with higher GSI and those presenting with functional dysphagia or pelvic floor dysfunction rate higher on the PSDI. Interestingly, patients with functional chest pain presented with lower PSDI scores than those without chest pain; we did not find significant differences in psychologic distress scores for the remaining FGIDs (Table 5).
      Table 5Standardized SCL-90R Global Index Regarding the Presence of Each FGID in Patients With FM
      Functional disorderPresentGSIPSTPSDI
      GlobusNo66.98 ± 7.0366.50 ± 7.8860.87 ± 7.00
      Yes67.00 ± 6.9266.00 ± 6.9265.00 ± 9.16
      Rumination syndromeNo66.90 ± 7.0266.48 ± 7.8960.91 ± 7.07
      Yes68.00 ± 6.0966.50 ± 7.4462.00 ± 7.07
      Functional chest painNo67.19 ± 6.8066.59 ± 7.7261.27 ± 6.91
      P < .05.
      Yes60.33 ± 11.5463.00 ± 12.1252.00 ± 6.55
      Functional dysphagiaNo66.94 ± 6.9466.41 ± 7.9260.61 ± 7.03
      Yes67.66 ± 8.4367.66 ± 6.5667.00 ± 4.38
      P < .05.
      Functional heartburnNo67.02 ± 7.0566.38 ± 7.8761.04 ± 7.03
      Yes66.66 ± 6.7267.55 ± 7.6560.55 ± 7.61
      Functional dyspepsiaNo67.62 ± 6.3666.94 ± 7.7161.40 ± 6.84
      Yes64.61 ± 8.7664.76 ± 8.1659.47 ± 7.76
      AerophagiaNo67.09 ± 7.0866.21 ± 8.0660.87 ± 7.14
      Yes66.47 ± 6.7067.82 ± 6.5561.58 ± 6.75
      IBSNo65.68 ± 7.3765.44 ± 8.1960.37 ± 6.84
      Yes69.02 ± 5.8968.12 ± 6.9961.97 ± 7.34
      Functional bloatingNo66.90 ± 7.1666.28 ± 7.6760.71 ± 7.15
      Yes67.14 ± 6.7566.88 ± 8.1961.55 ± 6.92
      Functional constipationNo67.27 ± 6.4866.81 ± 7.5660.94 ± 6.91
      Yes65.40 ± 9.5164.66 ± 9.2561.33 ± 8.04
      Functional diarrheaNo66.94 ± 7.0166.48 ± 7.8860.88 ± 6.97
      Yes69.00 ± 8.4866.50 ± 4.9465.50 ± 12.02
      Functional incontinenceNo64.92 ± 7.0664.65 ± 8.3859.29 ± 6.40
      Yes69.56 ± 6.09
      P < .001.
      68.73 ± 6.48
      P < .05.
      63.08 ± 7.31
      P < .05.
      Levator ani syndromeNo66.36 ± 7.0565.85 ± 7.8560.48 ± 6.84
      Yes69.08 ± 6.5268.60 ± 7.4862.73 ± 7.59
      Proctalgia fugaxNo66.70 ± 6.8566.06 ± 7.9660.67 ± 7.05
      Yes69.60 ± 8.0770.30 ± 5.2563.90 ± 6.69
      Pelvic floor dysfunctionNo66.80 ± 7.0266.52 ± 7.8260.55 ± 6.96
      Yes69.42 ± 6.6566.00 ± 8.1266.85 ± 5.84
      P < .05.
      Functional abdominal painNo67.06 ± 7.1066.32 ± 7.9161.10 ± 7.14
      Yes65.25 ± 3.5070.50 ± 3.3158.50 ± 4.20
      Unspecified functional abdominal painNo66.72 ± 6.8066.46 ± 7.8460.65 ± 6.57
      Yes68.10 ± 7.8766.57 ± 7.9662.47 ± 8.85
      Biliary painNo67.03 ± 7.0565.85 ± 7.8560.48 ± 6.84
      Yes69.08 ± 6.5268.60 ± 7.4862.73 ± 7.59
      a P < .05.
      b P < .001.
      Logistic regression models showed that primary psychologic symptom dimensions were associated significantly with the presence of different FGIDs: somatization with IBS; psychoticism with functional constipation; somatization with unspecified abdominal pain, somatization, and depression with functional incontinence; and depression with proctalgia fugax. On the other hand there was a negative correlation among the presence of interpersonal sensitivity with aerophagia and functional constipation, male sex and anxiety with unspecified functional abdominal pain, and psychoticism with functional incontinence. Table 6 summarizes the results of regression models.
      Table 6Results of Logistic Regression Analysis for Every FGID
      Functional disorderRelated factorAdjusted odds ratio
      GlobusNo
      Rumination syndromeNo
      Functional chest painNo
      Functional dysphagiaNo
      Functional heartburnNo
      Functional dyspepsiaNo
      AerophagiaInterpersonal sensitivity0.86 (0.76–0.98)
      P < .05.
      Functional vomitingNA
      Result not reached because of insufficient number of cases available to perform the statistics.
      IBSSomatization1.31 (1.09–1.58)
      P < .05.
      Functional abdominal bloatingNo
      Functional constipationInterpersonal sensitivity0.69 (0.52–0.92)
      P < .05.
      Psychoticism1.16 (1.01–1.36)
      P < .05.
      Functional diarrheaNo
      Functional abdominal painNo
      Unspecified functional abdominal painMale sex0.07 (0.01–0.66)
      P < .05.
      Somatization anxiety1.22 (1.01–1.49)
      P < .05.
      0.85 (0.73–0.99)
      P < .05.
      Gallbladder dysfunctionNo
      Sphincter of Oddi dysfunctionNA
      Result not reached because of insufficient number of cases available to perform the statistics.
      Functional incontinenceSomatization1.20 (1.02–1.41)
      P < .05.
      Depression1.14 (1.01–1.29)
      P < .05.
      Psychoticism0.90 (0.81–0.99)
      P < .05.
      Levator ani syndromeNo
      Proctalgia fugaxDepression1.40 (1.07–1.83)
      P < .05.
      Pelvic floor dysfunctionNA
      Result not reached because of insufficient number of cases available to perform the statistics.
      NA, not applicable.
      a P < .05.
      b Result not reached because of insufficient number of cases available to perform the statistics.

      Discussion

      Our study was designed with the purpose of better understanding the prevalence of FGIDs in Spanish patients with FM, as well as assessing whether certain psychologic abnormalities were related to the presence of FGID in patients with FM.
      In addition, we found a 6% prevalence of widespread pain among controls that reinforced the concept that this is a prevalent condition in the general population.
      • Wolfe F.
      • Ross K.
      • Anderson J.
      • et al.
      The prevalence and characteristics of fibromyalgia in the general population.
      • Croft P.
      • Rigby A.S.
      • Boswell R.
      • et al.
      The prevalence of chronic widespread pain in the general population.
      • Lindell L.
      • Bergman S.
      • Petersson I.F.
      • et al.
      Prevalence of fibromyalgia and chronic widespread pain.
      Our case-control study confirms the high prevalence of FGID in patients with FM and shows that nearly all patients with FM in our sample fulfilled Rome II criteria for any FGID.
      IBS was the most prevalent disorder in our sample of Spanish patients with FM (39%). This rate agrees with others who previously have published reports using different criteria to define IBS,
      • Wolfe F.
      • Smythe H.A.
      • Yunus M.B.
      • et al.
      The American College of Rheumatology 1990 criteria for the classification of fibromyalgia Report of the multicenter criteria committee.
      • Sperber A.D.
      • Atzmon Y.
      • Neumann L.
      • et al.
      Fibromyalgia in the irritable bowel syndrome: studies of prevalence and clinical implications.
      • Yunus M.B.
      • Masi A.T.
      • Aldag J.C.
      A controlled study of primary fibromyalgia syndrome: clinical features and association with other functional syndromes.
      • Yunus M.
      • Masi A.T.
      • Calabro J.J.
      • et al.
      Primary fibromyalgia (fibrositis): clinical study of 50 patients with matched normal controls.
      but is lower than those obtained by Kurland et al,
      • Kurland J.E.
      • Coyle W.J.
      • Winkler A.
      • et al.
      Prevalence of irritable bowel syndrome and depression in fibromyalgia.
      who in a population study in the United States estimated a prevalence of IBS in FM of 63% by Rome I and 81% by Rome II. These differences can be explained by a lower prevalence of IBS in the general Spanish population.
      • Mearin F.
      • Badia X.
      • Balboa A.
      • et al.
      Irritable bowel syndrome prevalence varies enormously depending on the employed diagnostic criteria: comparison of Rome II versus previous criteria in general population.
      • Hungin A.P.
      • Chang L.
      • Locke G.R.
      • et al.
      Irritable bowel syndrome in the United States: prevalence, symptom patterns and impact.
      Our study describes the association between FM and anorectal functional syndromes, mainly functional fecal incontinence. Despite the fact that this symptom rarely is reported spontaneously by patients,
      • Damon H.
      • Schott A.M.
      • Barth X.
      • et al.
      The French ORALIA Group
      Clinical characteristics and quality of life in a cohort of 621 patients with faecal incontinence.
      its prevalence in our population, of both patients (56%) and controls (32%), is striking and might be related to the characteristics of our sample (a majority of women with an average age of 50), although it still is higher than the prevalence of this symptom (range, 15%–18%) reported in populations of similar age and sex.
      • Reilly W.
      • Talley N.
      • Pemberton J.
      Fecal incontinence: prevalence and risk factors in the community.
      • Kalantar J.S.
      • Howell S.
      • Talley N.J.
      Prevalence of faecal incontinence and associated risk factors; an underdiagnosed problem in the Australian community?.
      Similar to Triadafilopoulos et al,
      • Triadafilopoulos G.
      • Simms R.W.
      • Goldenberg D.L.
      Bowel dysfunction in fibromyalgia syndrome.
      who reported a higher frequency of gastrointestinal complaints in patients with FM compared with others with osteoarthritis (73% vs 37%), in our study patients with FM reported gastrointestinal symptoms more often than controls (98% vs 49%). Furthermore, we show that among individuals with digestive complaints, those with FM reported an increased number of symptoms (11.5 vs 4.2) related to more areas of the gastrointestinal tract than those without FM. In fact, up to 52% of patients with FM referred to symptoms related to the 4 gastrointestinal segments compared with only 15% of controls.
      In our sample, patients with FM presented with significantly higher scores in the psychologic distress severity index than controls, as well as higher levels of somatization, obsessivity, interpersonal sensitivity, depression, and anxiety. Wolfe et al,
      • Wolfe F.
      • Smythe H.A.
      • Yunus M.B.
      • et al.
      The American College of Rheumatology 1990 criteria for the classification of fibromyalgia Report of the multicenter criteria committee.
      in a population-based study, using the SCL-90R questionnaire, concluded that those individuals fulfilling diagnostic criteria for FM presented a strong association with somatization and had significantly abnormal scores for global severity and positive items as measures of psychologic distress severity when compared with controls. Moreover, Sperber et al
      • Sperber A.D.
      • Atzmon Y.
      • Neumann L.
      • et al.
      Fibromyalgia in the irritable bowel syndrome: studies of prevalence and clinical implications.
      reported significantly higher scores of somatization in patients with FM and IBS when compared with IBS patients, IBS nonpatients, and controls. By using logistic regression we have confirmed that the presence of somatization is related to the presence of IBS in our patients with FM and also related to the presence of unspecified abdominal pain and functional fecal incontinence. Further, we have identified other psychologic variables overexpressed in patients with FM and FGID, such as psychoticism in functional constipation, and depression in functional incontinence and in proctalgia fugax. On the other hand, the logistic regression analysis also has shown that certain features might be related inversely to the diagnosis of some FGIDs, such as the presence of interpersonal sensitivity to aerophagia and functional constipation, male sex and anxiety to unspecified functional abdominal pain, and psychoticism to functional incontinence. However, given the small number of patients fulfilling criteria for aerophagia (n = 17), functional constipation (n = 15), unspecified functional abdominal pain (n = 19), and proctalgia fugax (n = 10), our findings in these syndromes should be interpreted cautiously and confirmed in larger studies.
      In patients with FM, the highest grades of psychologic distress were found among those presenting with functional incontinence. Koloski et al
      • Koloski N.A.
      • Talley N.J.
      • Boyce P.M.
      Epidemiology and health care seeking in the functional GI disorders: a population based study.
      previously showed that subjects from the general population who met criteria for functional fecal incontinence had higher scores of neuroticism, anxiety, and depression.
      Koloski et al
      • Koloski N.A.
      • Talley N.J.
      • Boyce P.M.
      Epidemiology and health care seeking in the functional GI disorders: a population based study.
      also described that having a FGID was associated with high levels of psychologic morbidity (neuroticism, somatic distress, and anxiety); however, the presence of these psychological conditions did not determine the health care seaking patterns (consulters/nonconsulters). Later, Locke et al
      • Locke G.R.
      • Weaver A.L.
      • Melton J.
      • et al.
      Psychosocial factors are linked to functional gastrointestinal disorders: a population based nested case control study.
      confirmed in a population-based, case-control study that psychologic factors were associated significantly with FGID, but none of the psychologic variables were associated with health-seeking behavior, suggesting that contrary to other studies that attributed the psychologic disturbances to the patient status
      • Whitehead W.E.
      • Bosmajian L.
      • Zonderman A.B.
      • et al.
      Symptoms of psychologic distress associated with irritable bowel syndrome: comparison of community and medical samples.
      • Drossman D.A.
      • McKee D.C.
      • Sandler R.S.
      • et al.
      Psychosocial factors in the irritable bowel syndrome A multivariate study of patients and nonpatients with irritable bowel syndrome.
      psychologic factors may be involved in the etiopathogenesis of FGID.
      Despite the fact that the existence of increased psychologic distress also may be attributed to the presence of a chronic and painful condition of unknown origin, community-based studies have described familial patterns of psychiatric disorder in FM.
      • Raphael K.G.
      • Janal M.N.
      • Nayak S.
      • et al.
      Familial aggregation of depression in fibromyalgia: a community-based test of alternate hypothesis.
      This enhances the view of this entity as an affective spectrum disorder, which also has been supported by Arnold et al
      • Arnold L.M.
      • Hudson J.I.
      • Hess E.V.
      • et al.
      Family study of fibromyalgia.
      and Hudson et al,
      • Hudson J.I.
      • Mangweth B.
      • Pope H.G.
      • et al.
      Family study of affective spectrum disorder.
      • Hudson J.I.
      • Arnold L.M.
      • Keck P.E.
      • et al.
      Family study of fibromyalgia and affective spectrum disorder.
      who showed the coaggregation of FM with other forms of affective spectrum disorders. Moreover, Schur et al,
      • Schur E.A.
      • Afari N.
      • Furberg H.
      • et al.
      Feeling bad in more ways than one: comorbidity patterns of medically unexplained and psychiatric conditions.
      in a cross-sectional study of a community sample of twins, found patterns consistent with comorbidity among medically unexplained conditions, which reinforced the idea that these entities could share a common pathogenetic pathway that might be determined genetically.
      Our findings support the hypothesis that FM and certain FGIDs constitute part of the same spectrum of diseases. This expression would be modulated by psychologic factors,
      • Whitehead W.E.
      • Palsson O.
      • Jones K.R.
      Systematic review of the comorbidity of irritable bowel syndrome with other disorders: what are the causes and implications?.
      although the lack of a FGID group without FM to compare and the cross-sectional design do not allow us to establish causality.
      It is fair to note that our study presented other limitations that deserve attention. First, patients were selected exclusively from a patient advocacy group and this sample might not be representative of the overall Spanish FM population. However, FIQ scores, which assess the degree of impairment related to FM, in our sample are consistent with those reported in a Spanish survey of FM outpatients (69.3 vs 63.6).
      • Ubago Linares M.D.
      • Ruiz-Pérez I.
      • Bermejo Pérez M.J.
      • et al.
      Analysis of the impact of fibromyalgia on quality of life: associated factors.
      Other limitations come from the survey nature of our study; subjects who agree to participate in a study could be more likely to communicate symptoms of any nature and this factor could overestimate the results.
      • Drossman D.A.
      Psychosocial factors and the disorders of GI function: what is the link?.
      In addition, given that our population was not evaluated clinically and structural diseases were not ruled out, is not known definitively if these subjects have a particular FGID or only present with a higher frequency of individual gastrointestinal symptoms that also could be related to side effects of certain drugs commonly used in FM, such as narcotics or nonsteroidal anti-inflammatory drugs. Unfortunately, these potential biases were not considered in our study design.
      An interesting hypothesis that could support the striking prevalence of FGID in patients with FM would be an increased visceral sensitivity added to the somatic hypersensitivity characteristic of FM in certain patients,
      • Wolfe F.
      • Smythe H.A.
      • Yunus M.B.
      • et al.
      The American College of Rheumatology 1990 criteria for the classification of fibromyalgia Report of the multicenter criteria committee.
      • Granges G.
      • Littlejohn G.
      Pressure pain threshold pain-free subjects in patients with chronic regional syndromes, and in patients with fibromyalgia syndrome.
      which may make them more vulnerable to report gastrointestinal symptoms. Previous studies have shown enhanced visceral sensitivity in patients with IBS when compared with FM and healthy subjects, in contrast to patients with FM who present with increased somatic sensitivity. Patients with IBS and FM show both visceral hypersensitivity and somatic hypersensitivity.
      • Chang L.
      • Mayer E.A.
      • Johnson T.
      Difference in somatic perception in female patients with irritable bowel syndrome with and without fibromyalgia.
      • Caldarella M.P.
      • Giamberardino M.A.
      • Sacco F.
      • et al.
      Sensitivity disturbances in patients with irritable bowel syndrome and fibromyalgia.
      Brain regions involved in the processing and/or modulation of both visceral and somatic afferent input as the anterior cingulated cortex have been implied in the pathogenesis of these sensitivity disturbances found in IBS and FM.
      • Mertz H.
      • Morgan V.
      • Tanner G.
      • et al.
      Regional cerebral activation in irritable bowel syndrome and control subjects with painful and nonpainful rectal distension.
      Previously conducted studies using functional magnetic resonance neuroimaging and positron emission tomography have noted a greater activation of the anterior cingulated cortex after visceral stimulation in patients with IBS, somatic stimulation in patients with FM, and both somatic and visceral stimuli in patients with FM and IBS.
      • Chang L.
      • Berman S.
      • Mayer E.A.
      • et al.
      Brain responses to visceral and somatic stimuli in patients with irritable bowel syndrome with and without fibromyalgia.
      • Verne N.
      • Himes N.
      • Robinson M.
      • et al.
      Central representation of visceral and cutaneous hypersensitivity in the irritable bowel syndrome.
      Given that the anterior cingulated cortex can be divided into 3 functional subregions: one activated during painful stimuli, another during attentional tasks, and the last one during emotional tasks,
      • Petrovic P.
      • Kalso E.
      • Peterson K.M.
      • et al.
      Placebo and opioid analgesia-imaging a shared neuronal network.
      it would not be illogical to consider that the 3 factors aforementioned might interact together in the pathogenesis and/or perception of symptoms in patients with coexisting FM and FGID. Such a hypothesis could explain the high rates of gastrointestinal symptoms as well as the increased levels of psychologic distress, but needs to be tested in an appropriately designed study.
      To summarize, despite its limitations, our study of the Spanish population reports the overall and individual prevalences of FGID in patients with FM; describing in patients not only a higher prevalence of gastrointestinal symptoms but also a wider distribution of such symptoms along the gastrointestinal tract when compared with controls. Furthermore, we have confirmed an increased degree of psychologic distress in patients with FM, and the potential role that psychologic features can play in patients with FM related to the presence of certain FGIDs, which seems to be especially significant for anorectal syndromes.

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