title: Studying psychosocial adaptation to end-stage renal disease: the proximal-distal model of health-related outcomes as a base model.
abstract: OBJECTIVE
  Studying psychosocial adaptation in end-stage renal disease (ESRD) is increasingly important, as it may explain the variability in health outcomes unaccounted for by clinical factors. The Brenner et al. proximal-distal model of health-related outcomes provides a theoretical foundation for understanding psychosocial adaptation and integrating health outcomes, clinical, and psychosocial factors (Brenner MH, Curbow B, Legro MW. The proximal-distal continuum of multiple health outcome measures: the case of cataract surgery. Med Care. 1995;33(4 Suppl):AS236-44). This study aims to empirically validate the proximal-distal model in the dialysis population and examine the impact of psychosocial factors on the model.
  
  
  METHODS
  A cross-sectional observational study was conducted with a sample of long-term dialysis patients (n=201). Eleven factors: quality of life (QoL), depression, positive affect, comorbidity, symptoms, physical functioning, disease accommodation, loss, self-efficacy, illness acceptance, and social support were measured by standardized psychometric scales. A three-month average of hemoglobin was used. Latent composite structural equation modeling was used to examine the models.
  
  
  RESULTS
  The proximal-distal model with slight modification was supported by fit statistics [χ(2)=16.04, df=13, P=.25, root mean square error of approximation (RMSEA)=0.024], indicating that the impact of clinical factors on QoL is mediated through a range of functional and psychological factors, except for hemoglobin which impacts directly on QoL. The model with additional psychosocial factors was also supported by fit statistics (χ(2)=43.59, df=41, P=.36, RMSEA=0.018). These additional factors mainly impact on symptom status, psychological states, and QoL components of the model.
  
  
  CONCLUSIONS
  The present study supported the proximal-distal model in the dialysis population and demonstrated the considerable impact of psychosocial factors on the model. The proximal-distal model plus psychosocial factors as a biopsychosocial model can be applied to studying psychosocial adaptation in ESRD.
authors.affiliation: Consultation Liaison Psychiatry, Liverpool Hospital, Sydney, Australia. ramony.chan@sswahs.nsw.gov.au
authors.forename: Ramony
authors.initials: R
authors.lastname: Chan
authors.forename: Robert
authors.initials: R
authors.lastname: Brooks
authors.forename: Jonathan
authors.initials: J
authors.lastname: Erlich
authors.forename: Martin
authors.initials: M
authors.lastname: Gallagher
authors.forename: Paul
authors.initials: P
authors.lastname: Snelling
authors.forename: Josephine
authors.initials: J
authors.lastname: Chow
authors.forename: Michael
authors.initials: M
authors.lastname: Suranyi
mesh_terms: D000223:Adaptation, Psychological; D000328:Adult; D000339:Affect; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D003863:Depression / Q000523:psychology; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D011788:Quality of Life / Q000523:psychology*; D006435:Renal Dialysis; D020377:Self Efficacy; D012944:Social Support