title: The association between somatization and disability in primary care patients.
abstract: BACKGROUND
  Patient encounters for medically unexplained physical symptoms are common in primary health care. Somatization ('experiencing and reporting unexplained somatic symptoms') may indicate concurrent or future disability but this may also partly be caused by psychiatric disorders. The aim of this study was to examine the cross-sectional and longitudinal association between somatization and disability in primary care patients with and without anxiety or depressive disorder.
  
  
  METHODS
  Data were obtained from 1545 primary care patients, participating in the longitudinal Netherlands Study of Depression and Anxiety (NESDA). Somatization was assessed using the somatization scale of the Four-Dimensional Symptom Questionnaire (4DSQ). Disability was determined by the WHO Disability Assessment Schedule 2.0 (WHO-DAS II). The relationships between somatization and both the total and subdomain scores of the WHO-DAS II were measured cross-sectionally and longitudinally after one year of follow-up using linear regression analysis. We examined whether anxiety or depressive disorder exerted a modifying effect on the somatization-disability association.
  
  
  RESULTS
  Cross-sectionally and longitudinally, somatization was significantly associated with disability. Somatization accounted cross-sectionally for 41.8% of the variance in WHO-DAS disability and, longitudinally, for 31.7% of the variance in disability after one year of follow-up. The unique contribution of somatization to disability decreased to 16.7% cross-sectionally and 15.7% longitudinally, when anxiety and/or depressive disorder was added to the model.
  
  
  CONCLUSIONS
  Somatization contributes to the presence of disability in primary care patients, even when the effects of baseline demographic and health characteristics and anxiety or depressive disorder are taken into account.
authors.affiliation: Faculty of Medicine of the University of Utrecht, Utrecht, The Netherlands; College of Nursing and Health Sciences, University of Massachusetts Boston, Boston, MA, USA. Electronic address: Guusje.leeuw@umb.edu.
authors.forename: G
authors.initials: G
authors.lastname: van der Leeuw
authors.affiliation: Department of Psychiatry, EMGO Institute for Health and Care Research, VU University Medical Center and Academic Outpatient Clinic for Affective Disorders, GGZ in Geest, Amsterdam, The Netherlands; Department of General Practice and Elderly Care Medicine, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Gerrits
authors.affiliation: Department of General Practice and Elderly Care Medicine, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Terluin
authors.affiliation: Department Public Health and Primary Care, Leiden University Medical Center, The Netherlands.
authors.forename: M E
authors.initials: ME
authors.lastname: Numans
authors.affiliation: Tranzo Department, Faculty of Social Sciences of the University of Tilburg, Tilburg, The Netherlands; Topclinical Center for Body, Mind and Health, Tilburg, The Netherlands.
authors.forename: C M
authors.initials: CM
authors.lastname: van der Feltz-Cornelis
authors.affiliation: Department of General Practice and Elderly Care Medicine, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: H E
authors.initials: HE
authors.lastname: van der Horst
authors.affiliation: Department of Psychiatry, EMGO Institute for Health and Care Research, VU University Medical Center and Academic Outpatient Clinic for Affective Disorders, GGZ in Geest, Amsterdam, The Netherlands.
authors.forename: B W J H
authors.initials: BW
authors.lastname: Penninx
authors.affiliation: Department of General Practice and Elderly Care Medicine, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands; Centre for Primary Care, Institute of Population Health, University of Manchester, United Kingdom. Electronic address: harm.vanmarwijk@manchester.ac.uk.
authors.forename: H W J
authors.initials: HW
authors.lastname: van Marwijk
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001008:Anxiety Disorders / Q000150:complications / Q000523:psychology; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000150:complications / Q000523:psychology; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007398:Interpersonal Relations; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D011320:Primary Health Care; D011569:Psychiatric Status Rating Scales; D012648:Self Care; D013001:Somatoform Disorders / Q000150:complications / Q000523:psychology*; D055815:Young Adult
keywords: Anxiety disorders; Depressive disorders; Disability; Primary care; Somatization