title: The association between critical illness and changes in bone turnover in adults: a systematic review.
abstract: CONCLUSIONS
  Critical illness may lead to altered bone turnover and associated adverse health outcomes. This systematic review found moderate evidence for a positive association between critical illness and increased bone turnover. Prospective cohort studies that identify the extent and risk factors for critical illness related bone loss are required.
  
  
  BACKGROUND
  Intensive care patients face health issues that extend beyond their critical illness and result in significant morbidity and mortality. Critical illness may result in altered bone turnover due to associated immobilisation, inflammation, exposure to medications that effect bone and calcium metabolism, and endocrine dysfunction. The aim of this study was to synthesise the existing evidence for altered bone turnover in adults admitted to intensive care.
  
  
  METHODS
  A literature search using MEDLINE and EMBASE was performed from 1965 to March 2013. Reviewed studies investigated the relationship between critical illness and evidence of altered bone turnover (bone turnover markers, bone mineral density, or fracture). Studies were rated upon their methodological quality, and a best-evidence synthesis was used to summarise the results.
  
  
  RESULTS
  Four cohort and seven case-control studies were identified for inclusion, of which five studies were rated as being of higher methodological quality. Ten of the studies measured bone turnover markers, and one study fracture rate. Findings were consistent across studies, and best-evidence analysis resulted in a conclusion that moderate evidence exists for an association between critical illness requiring admission to intensive care and altered bone turnover.
  
  
  CONCLUSIONS
  A positive association between critical illness requiring intensive care admission and bone turnover exists, although data are limited, and the risk factors and the nature of the relationship are not yet understood. Prospective cohort studies that identify risk factors and extent of critical illness related bone turnover changes are required.
authors.affiliation: Australian and New Zealand Intensive Care Research Centre (ANZIC-RC), Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia, orfords@me.com.
authors.forename: N
authors.initials: N
authors.lastname: Orford
authors.forename: C
authors.initials: C
authors.lastname: Cattigan
authors.forename: S L
authors.initials: SL
authors.lastname: Brennan
authors.forename: M
authors.initials: M
authors.lastname: Kotowicz
authors.forename: J
authors.initials: J
authors.lastname: Pasco
authors.forename: D J
authors.initials: DJ
authors.lastname: Cooper
mesh_terms: D015519:Bone Density / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology*; D003422:Critical Care; D016638:Critical Illness; D006801:Humans; D010024:Osteoporosis / Q000209:etiology* / Q000503:physiopathology