title: The role of perceived control and preference for control in adherence to a chronic medical regimen.
abstract: BACKGROUND
  Poor patient adherence is a widespread problem among patients undergoing hemodialysis for end-stage renal disease.
  
  
  OBJECTIVE
  The goal of this study was to examine the joint role of perceived restriction of control and individual differences in preference for control in predicting adherence to the hemodialysis regimen.
  
  
  METHODS
  Participants were 49 patients recruited from five hemodialysis centers affiliated with the University of Iowa Hospitals and Clinics. Preference for control in the health care context was assessed using the Preference for Information and Preference for Behavioral Involvement subscales of the Krantz Health Opinion Survey, and perceived control was assessed using six items written for this study. Adherence was assessed by examining patients' interdialysis session weight gains (IWG).
  
  
  RESULTS
  Hierarchical regression analysis indicated that the interaction between preference for information and perceived control over dialysis context explained a significant proportion of variance in IWG values, change in R2 =.09, F(1, 43) = 5.26, p <.05, standardized beta = -.32. Among patients with lower levels of perceived control in the dialysis setting, a higher preference for information concerning one's own health care was associated with increasingly poorer adherence. IWG levels in these individuals reflected clinically problematic nonadherence with fluid-intake restrictions. Among patients with a higher level of perceived control, preference for information had little effect on adherence. No main or interactive effects were found involving differences in patients' preference for behavioral involvement in their own health care or for the items reflecting perceived control outside the dialysis treatment setting.
  
  
  CONCLUSIONS
  These data suggest that assessing and examining the interactive effects of patients' preferences for control and perceived control may, in some cases, be useful in identifying those individuals at risk for difficulty in adhering to the complex behavioral restrictions associated with chronic medical regimens.
authors.affiliation: Department of Psychology, University of Iowa, Iowa City 52242, USA. jamie.cvengros@uiowa.edu
authors.forename: Jamie A
authors.initials: JA
authors.lastname: Cvengros
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Christensen
authors.forename: William J
authors.initials: WJ
authors.lastname: Lawton
mesh_terms: D001294:Attitude to Health; D005260:Female; D006801:Humans; D007389:Internal-External Control; D007484:Iowa; D007676:Kidney Failure, Chronic / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000523:psychology; D012044:Regression Analysis; D006435:Renal Dialysis / Q000523:psychology