title: Symptom clusters in patients receiving haemodialysis: a systematic review of observational studies.
abstract: OBJECTIVE
  To systematically review the common composition and the analytical methods performed to derive symptom clusters in patients receiving haemodialysis, and to examine their common predictive and outcome variables.
  
  
  BACKGROUND
  Patients receiving haemodialysis may suffer from multiple and interactive symptoms simultaneously, which may impact their mortality, morbidity and quality of life. The composition of these symptom clusters varies depending on the different assessment tools, the variant evaluation timing points and the various statistical methodologies. A detailed review of existing studies is needed.
  
  
  METHODS
  A systematic review of observational studies.
  
  
  METHODS
  Medline from 1950, CINAHL from 1960, Embase from 1980 and PsycINFO from 1967 as well as additional sources were searched. Content analysis was conducted to identify articles assessing the interrelationships of multiple symptoms.
  
  
  RESULTS
  Five studies were identified. Several symptom clusters were identified with five common groupings being uraemic cluster, neuromuscular cluster, skin cluster, gastrointestinal cluster and energy/fatigue cluster. Four studies performed the principal component analysis with varimax rotation to extract symptom clusters and one study used correlation analysis. Different symptom assessment tools were used and each involving different array of symptoms. The predictive and outcome variables of symptom clusters also varied considerably. No studies have examined the longitudinal course and patients' subjective experiences of symptom clusters.
  
  
  CONCLUSIONS
  Inconsistencies in the composition of symptom clusters across studies were identified due to inconsistencies in symptom assessment tools and statistical methodologies. Future studies should focus on an agreement about a robust and clinically relevant definition on symptom clusters; a multidimensional, valid and reliable symptom assessment tool; and an optimal analytical method in patients receiving haemodialysis.
  
  
  CONCLUSIONS
  Knowledge of symptom clusters may contribute to understanding the aetiology and pathophysiology of multiple concurrent and interactive symptoms in patients receiving haemodialysis and exploring the effects of these symptoms on clinical outcomes.
authors.affiliation: Department of Nephrology, Hemodialysis Center, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China.
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Cao
authors.affiliation: Department of Hepatobilliary Surgery, Sichuan Cancer Hospital, Chengdu, Sichuan Province, China.
authors.forename: Lang
authors.initials: L
authors.lastname: Tian
authors.affiliation: Department of Nephrology, Hemodialysis Center, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Lin
mesh_terms: D016000:Cluster Analysis; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications* / Q000628:therapy; D064887:Observational Studies as Topic; D025341:Principal Component Analysis; D011788:Quality of Life; D006435:Renal Dialysis / Q000451:nursing; D063189:Symptom Assessment
keywords: haemodialysis; symptom perception; systematic review