title: Locus of control and frequency of physician visits: Results of a population-based longitudinal study in Germany.
abstract: To examine the role of internal and external locus of control (LOC) in the frequency of physician visits longitudinally.
  
  
  
  A nationally representative, longitudinal cohort study of German households. Data were used from the years 2005 and 2010.
  
  
  
  Data were gathered from the German Socio-Economic Panel (GSOEP). The ten internal and external LOC items in the SOEP are based on a scale by Krampen. The number of physician visits in the last 3 months was used as outcome variable. According to Andersen's behavioural model, predisposing characteristics, enabling resources, and need factors were included as control variables.
  
  
  
  Fixed-effects Poisson regressions showed that physician visits increased with increasing external LOC, whereas changes in internal LOC were not associated with changes in physician visits. Furthermore, physician visits increased with need factors (decreased self-rated health; onset of disability), whereas predisposing characteristics and the enabling resources were not associated with physician visits.
  
  
  
  Our findings emphasize the meaning of changes in external LOC for physician visits. As there is evidence that interventions can change the LOC, efforts to modify external LOC might be beneficial for the health care system. Statement of contribution What is already known on this subject? A few cross-sectional studies have investigated the association between locus of control (LOC) and health care use. Longitudinal studies are needed to get a deeper understanding of the causal relationship between these factors. What does this study add? Our longitudinal study provides insights into the impact of general internal and external LOC on physician visits. This is the first study examining the long-term relation in Germany using a population-based sample.
authors.affiliation: Department of Health Economics and Health Services Research, Hamburg Center for Health Economics, University Medical Center Hamburg-Eppendorf, Germany.
authors.forename: André
authors.identifier: 0000-0002-6886-2745
authors.initials: A
authors.lastname: Hajek
authors.affiliation: Department of Health Economics and Health Services Research, Hamburg Center for Health Economics, University Medical Center Hamburg-Eppendorf, Germany.
authors.forename: Hans-Helmut
authors.initials: HH
authors.lastname: König
mesh_terms: D015331:Cohort Studies; D005260:Female; D005858:Germany; D006296:Health Services / Q000706:statistics & numerical data*; D006801:Humans; D007389:Internal-External Control; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009819:Office Visits / Q000706:statistics & numerical data*
keywords: doctor visits; health behaviour; health care; locus of control; regression