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The Latent Structure of Medically Unexplained Symptoms and Its Relation to Functional Somatic Syndromes

  • Michael WitthöftEmail author
  • Wolfgang Hiller
  • Noelle Loch
  • Fabian Jasper
Article

Abstract

Background

Medically unexplained symptoms are the hallmark of somatoform disorders and functional somatic syndromes.

Purpose

Although medically unexplained symptoms represent a common phenomenon both in the general population as well as in medical settings, the exact latent structure of somatic symptoms remains largely unclear.

Method

We examined the latent structure of medically unexplained symptoms by means of the Patient Health Questionnaire-15 (PHQ-15) questionnaire (i.e., a popular symptom checklist) and provide support for the construct validity of our model. The data were analyzed using confirmatory factor analysis in a general population sample (study 1; N = 414) and in a sample of primary care patients (study 2; N = 308). We compared four different latent structure models of medically unexplained symptoms: a general factor model, a correlated group factor model, a hierarchical model, and a bifactor model.

Results

In study 1, a bifactor model with one general factor and four independent specific symptom factors (i.e., gastrointestinal, pain, fatigue, and cardiopulmonary symptoms) showed the best model fit. This bifactor model was confirmed in the primary care sample (study 2). Additionally, the model explained 59 % of the variance of the irritable bowel syndrome (IBS). In this structural equation model, both the general factor (14 %) as well as the gastrointestinal symptom factor (42 %) significantly predicted the IBS.

Conclusion

The findings of both studies help to clarify the latent structure of somatic symptoms in the PHQ-15. The bifactor model outperformed alternative models and demonstrated external validity in predicting IBS.

Keywords

Medically unexplained symptoms (MUS) Somatization Somatoform disorders Functional somatic syndromes Irritable bowel syndrome (IBS) Confirmatory factor analysis Nested factor model Bifactor model 

Notes

Acknowledgments

The study was supported by a research grant of the German Academic Exchange Service (DAAD) awarded to Michael Witthöft.

References

  1. 1.
    Hiller W, Rief W, Brähler E. Somatization in the population: from mild bodily misperceptions to disabling symptoms. Soc Psych Psych Epid. 2006;41(9):704–12. d oi: 10.1007/s00127-006-0082-y.CrossRefGoogle Scholar
  2. 2.
    American Psychiatric Association. Diagnostic and statistical manual of mental disorders—DSM-IV-TR. 4th ed. Washington: American Psychiatric Association; 2000.Google Scholar
  3. 3.
    Witthöft M, Hiller W. Psychological approaches to origins and treatments of somatoform disorders. Annu Rev Clin Psycho. 2010;6:257–83.CrossRefGoogle Scholar
  4. 4.
    Hanel G, Henningsen P, Herzog W, et al. Depression, anxiety, and somatoform disorders: vague or distinct categories in primary care? Results from a large cross-sectional study. J Psychosom Res. 2009;67(3):189–97.PubMedCrossRefGoogle Scholar
  5. 5.
    Toft T, Fink P, Oernboel E, Christensen K, Frostholm L, Olesen F. Mental disorders in primary care: prevalence and co-morbidity among disorders. Results from the Functional Illness in Primary care (FIP) study. Psychol Med. 2005;35(8):1175–84.PubMedCrossRefGoogle Scholar
  6. 6.
    Deary V, Chalder T, Sharpe M. The cognitive behavioural model of medically unexplained symptoms: a theoretical and empirical review. Clin Psychol Rev. 2007;27(7):781–97.PubMedCrossRefGoogle Scholar
  7. 7.
    Schumacher S, Rief W, Brähler E, Martin A, Glaesmer H, Mewes R. Disagreement in doctor's and patient's rating about medically unexplained symptoms and health care use. Int J Behav Med. 2011. doi: 10.1007/s12529-011-9213-2.
  8. 8.
    Deary IJ. A taxonomy of medically unexplained symptoms. J Psychosom Res. 1999;47(1):51–9.PubMedCrossRefGoogle Scholar
  9. 9.
    Kroenke K, Spitzer RL, deGruy FV, Swindle R. A symptom checklist to screen for somatoform disorders in primary care. Psychosomatics. 1998;39(3):263–72.PubMedCrossRefGoogle Scholar
  10. 10.
    Mcnemar Q. Opinion-attitude methodology. Psychol Bull. 1946;43(4):289–374.PubMedCrossRefGoogle Scholar
  11. 11.
    Wessely S, Nimnuan C, Sharpe M. Functional somatic syndromes: one or many? Lancet. 1999;354(9182):936–9.PubMedCrossRefGoogle Scholar
  12. 12.
    McGrath RE, Walters GD. Taxometric Analysis as a General Strategy for Distinguishing Categorical From Dimensional Latent Structure. Psychol Methods. 2012. doi: 10.1037/a0026973.
  13. 13.
    Fink P, Toft T, Hansen MS, Ornbol E, Olesen F. Symptoms and syndromes of bodily distress: an exploratory study of 978 internal medical, neurological, and primary care patients. Psychosom Med. 2007;69(1):30–9.PubMedCrossRefGoogle Scholar
  14. 14.
    Liu G, Clark MR, Eaton WW. Structural factor analyses for medically unexplained somatic symptoms of somatization disorder in the epidemiologic catchment area study. Psychol Med. 1997;27(3):617–26.PubMedCrossRefGoogle Scholar
  15. 15.
    Jasper FW, H.; Rist, F.; Bailer, J.; Witthöft, M. Somatic symptom reporting has a dimensional latent structure: results from taxometric analyses. J Abnorm Psych. 2012 (in press).Google Scholar
  16. 16.
    Thomas ML, Locke DEC. Psychometric properties of the MMPI-2-RF somatic complaints (RC1) scale. Psychol Assess. 2010;22(3):492–503.PubMedCrossRefGoogle Scholar
  17. 17.
    Meehl PE. Clarifications about taxometric method. Appl Prev Psychol. 1999;8(3):165–74.CrossRefGoogle Scholar
  18. 18.
    Meehl PE. What's in a taxon? J Abnorm Psych. 2004;113(1):39–43.CrossRefGoogle Scholar
  19. 19.
    Lombardi VC, Ruscetti FW, Das Gupta J. Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome. Science. 2009;326(5952):585–9.PubMedCrossRefGoogle Scholar
  20. 20.
    Robbins JM, Kirmayer LJ, Hemami S. Latent variable models of functional somatic distress. J Nerv Ment Dis. 1997;185(10):606–15.PubMedCrossRefGoogle Scholar
  21. 21.
    Taylor R, Jason LA, Schoeny ME. Evaluating latent variable models of functional somatic distress in a community-based sample. J Ment Health. 2001;10(3):335–49.CrossRefGoogle Scholar
  22. 22.
    Nimnuan C, Rabe-Hesketh S, Wessely S, Hotopf M. How many functional somatic syndromes? J Psychosom Res. 2001;51(4):549–57.PubMedCrossRefGoogle Scholar
  23. 23.
    Lee S, Ma YL, Tsang A. Psychometric properties of the Chinese 15-item patient health questionnaire in the general population of Hong Kong. J Psychosom Res. 2011;71(2):69–73.PubMedCrossRefGoogle Scholar
  24. 24.
    Mewes R, Christ O, Rief W, Brahler E, Martin A, Glaesmer H. Are depression and somatisation equivalent for migrants and native Germans? An investigation of measurement invariance for the PHQ-9 and PHQ-15. Diagnostica. 2010;56(4):230–9.CrossRefGoogle Scholar
  25. 25.
    Hu LT, Bentler PM. Cutoff criteria for fit indexes in covariance structure analysis: conventional criteria versus new alternatives. Struct Equ Modeling. 1999;6(1):1–55.CrossRefGoogle Scholar
  26. 26.
    Thurstone LL. Multiple-factor analysis. Chicago: University of Chicago Press; 1947.Google Scholar
  27. 27.
    Chen FF, West SG, Sousa KH. A comparison of bifactor and second-order models of quality of life. Multivar Behav Res. 2006;41(2):189–225.CrossRefGoogle Scholar
  28. 28.
    Yung YF, Thissen D, McLeod LD. On the relationship between the higher-order factor model and the hierarchical factor model. Psychometrika. 1999;64(2):113–28.CrossRefGoogle Scholar
  29. 29.
    Tellegen A, Ben-Porath YS. MMPI-2-RF technical manual. Minneapolis: University of Minnesota Press; 2011.Google Scholar
  30. 30.
    Kroenke K, Spitzer RL, Williams JB. The PHQ-15: validity of a new measure for evaluating the severity of somatic symptoms. Psychosom Med. 2002;64(2):258–66.PubMedGoogle Scholar
  31. 31.
    Loehlin JC. Latent variable models: an introduction to factor, path, and structural equation analysis. 4th Ed. ed. Mahwah: LEA; 2003.Google Scholar
  32. 32.
    Spitzer RL, Williams JB, Kroenke K. Prime MD today. Evaluation of mental disorders. manual. USA: Pfizer US; 1999.Google Scholar
  33. 33.
    Löwe B, Spitzer RL, Zipfel S, Herzog W. PHQ-D. Gesundheitsfragebogen für Patienten. Manual Komplettversion und Kurzform. Karlsruhe: Pfizer; 2002.Google Scholar
  34. 34.
    American Psychiatric Association. DSM-5 development—complex somatic symptom disorder [Internet]. Arlington: American Psychiatric Association; 2012. Available from: http://www.dsm5.org/ProposedRevisions/Pages/proposedrevision.aspx?rid=368#.
  35. 35.
    Horn JL. A rationale and test for the number of factors in factor-analysis. Psychometrika. 1965;30(2):179–85.PubMedCrossRefGoogle Scholar
  36. 36.
    Muthén LK, Muthén BO. Mplus user’s guide. Los Angeles: Muthén & Muthén; 2010.Google Scholar
  37. 37.
    Beauducel A, Herzberg PY. On the performance of maximum likelihood versus means and variance adjusted weighted least squares estimation in CFA. Struct Equ Modeling. 2006;13(2):186–203.CrossRefGoogle Scholar
  38. 38.
    Muthén B, du Toit, S. H-C., Spisic, D. Robust inference using weighted least squares and quadratic estimating equations in latent variable modeling with categorical and continuous outcomes. Unpublished manuscript. 1997.Google Scholar
  39. 39.
    Beauducel A, Wittmann WW. Simulation study on fit indexes in CFA based on data with slightly distorted simple structure. Struct Equ Modeling. 2005;12(1):41–75.CrossRefGoogle Scholar
  40. 40.
    Schermelleh-Engel K, Moosbrugger H, Müller H. Evaluating the fit of structural equation models: tests of significance and descriptive goodness-of-fit measures. Meth Psychol Res Online. 2003;8:23–74.Google Scholar
  41. 41.
    Körber S, Frieser D, Steinbrecher N, Hiller W. Classification characteristics of the Patient Health Questionnaire-15 for screening somatoform disorders in a primary care setting. J Psychosom Res. 2011;71(3):142–7.PubMedCrossRefGoogle Scholar
  42. 42.
    Drossman DA, Corazziari E, Talley NJ, et al. Rome II: The functional gastrointestinal disorders. Diagnosis, pathophysiology and treatment. A multinational consensus. Lawrence: Allen; 2000.Google Scholar
  43. 43.
    Tak LM, Rosmalen JGM. Dysfunction of stress responsive systems as a risk factor for functional somatic syndromes. J Psychosom Res. 2010;68:461–8.PubMedCrossRefGoogle Scholar
  44. 44.
    Ehlert U, Gaab J, Heinrichs M. Psychoneuroendocrinological contributions to the etiology of depression, posttraumatic stress disorder, and stress-related bodily disorders: the role of the hypothalamus–pituitary–adrenal axis. Biol Psychol. 2001;57:141–52.PubMedCrossRefGoogle Scholar
  45. 45.
    Fink P, Schröder A. One single diagnosis, bodily distress syndrome, succeeded to capture 10 diagnostic categories of functional somatic syndromes and somatoform disorders. J Psychosom Res. 2010;68:415–26.PubMedCrossRefGoogle Scholar
  46. 46.
    Moss-Morris R, Spence M. To "lump" or to "split" the functional somatic syndromes: can infectious and emotional risk factors differentiate between the onset of chronic fatigue syndrome and irritable bowel syndrome? Psychosom Med. 2006;68(3):463–9.PubMedCrossRefGoogle Scholar
  47. 47.
    Kato K, Sullivan PF, Evengård B, Pedersen NL. A population-based twin study of functional somatic syndromes. Psychol Med. 2009;39(3):497–505.PubMedCrossRefGoogle Scholar
  48. 48.
    Dimsdale JEC. F. H. The proposed diagnosis of somatic symptom disorders in DSM-V to replace somatoform disorders in DSM-IV—a preliminary report: author's response to letters from Shröder and van der Feltz-Cornelis. J Psychosom Res. 2010;68:100.CrossRefGoogle Scholar
  49. 49.
    Dimsdale J, Creed F. Disorders D-VWoSS. The proposed diagnosis of somatic symptom disorders in DSM-V to replace somatoform disorders in DSM-IV—a preliminary report. J Psychosom Res. 2009;66(6):473–6.PubMedCrossRefGoogle Scholar
  50. 50.
    Schumacher S, Rief W, Brähler E, Martin A, Glaesmer H, Mewes R. Disagreement in doctor’s and patient’s rating about medically unexplained symptoms and health care use. Int J Behav Med. 2011. doi: 10.1007/s12529-011-9213-2.
  51. 51.
    Hattie J. Methodology review—assessing unidimensionality of tests and items. Appl Psych Meas. 1985;9(2):139–64.CrossRefGoogle Scholar
  52. 52.
    Rief W, Hiller W. Screening für Somatoforme Störungen (SOMS). Manual. (2., vollständig überarbeitete und neu normierte Auflage) [Screening for somatoform disorders (SOMS), test manual, 2nd edition]. Bern: Hans Huber; 2008.Google Scholar

Copyright information

© International Society of Behavioral Medicine 2012

Authors and Affiliations

  • Michael Witthöft
    • 1
    • 2
    Email author
  • Wolfgang Hiller
    • 1
  • Noelle Loch
    • 1
  • Fabian Jasper
    • 1
  1. 1.Division of Clinical Psychology and PsychotherapyJohannes Gutenberg University of MainzMainzGermany
  2. 2.Department of Psychological Medicine, Institute of Psychiatry, Weston Education CentreKing’s College (Visiting Researcher)LondonUK

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