title: The natural history of untreated severe or critical limb ischemia.
abstract: OBJECTIVE
  Critical limb ischemia (CLI) is associated with high morbidity and mortality. Because most patients with CLI will eventually undergo some type of revascularization, the natural history of CLI is not well defined, although it is important to know when patients decide to pursue treatment.
  
  
  METHODS
  We systematically searched multiple databases for controlled and uncontrolled studies of patients with CLI who did not receive revascularization with a minimum follow-up of ≥1 year. Predefined outcomes of interest were mortality, major amputation, and wound healing. Random-effects meta-analysis was used to pool cumulative incidence across studies.
  
  
  RESULTS
  We identified 13 studies enrolling 1527 patients. During a median follow-up of 12 months, all-cause mortality rate was 22% (confidence interval [CI], 12%-33%) and major amputation rate was 22% (CI, 2%-42%). Worsened wound or ulcer was found at 35% (CI, 10%-62%). There was a trend toward improvement in mortality and amputation rate in studies done after 1997. The quality of evidence was low because of increased risk of bias and inconsistency.
  
  
  CONCLUSIONS
  Mortality and major amputations are common in patients who have untreated CLI during a median follow-up of 1 year, although these outcomes have improved in recent times.
authors.affiliation: Division of Preventive, Occupational, and Aerospace Medicine, Mayo Clinic, Rochester, Minn; The Knowledge Synthesis Unit, The Center for Healthcare Delivery, Mayo Clinic, Rochester, Minn.
authors.forename: Abd Moain
authors.initials: AM
authors.lastname: Abu Dabrh
authors.affiliation: Division of Preventive, Occupational, and Aerospace Medicine, Mayo Clinic, Rochester, Minn.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Steffen
authors.affiliation: The Knowledge Synthesis Unit, The Center for Healthcare Delivery, Mayo Clinic, Rochester, Minn.
authors.forename: Chaitanya
authors.initials: C
authors.lastname: Undavalli
authors.affiliation: The Knowledge Synthesis Unit, The Center for Healthcare Delivery, Mayo Clinic, Rochester, Minn.
authors.forename: Noor
authors.initials: N
authors.lastname: Asi
authors.affiliation: The Knowledge Synthesis Unit, The Center for Healthcare Delivery, Mayo Clinic, Rochester, Minn.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: The Knowledge Synthesis Unit, The Center for Healthcare Delivery, Mayo Clinic, Rochester, Minn.
authors.forename: Mohamed B
authors.initials: MB
authors.lastname: Elamin
authors.affiliation: Division of Vascular and Endovascular Surgery, University of California San Francisco, San Francisco, Calif.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Conte
authors.affiliation: Division of Preventive, Occupational, and Aerospace Medicine, Mayo Clinic, Rochester, Minn; The Knowledge Synthesis Unit, The Center for Healthcare Delivery, Mayo Clinic, Rochester, Minn. Electronic address: murad.mohammad@mayo.edu.
authors.forename: Mohammad Hassan
authors.initials: MH
authors.lastname: Murad
mesh_terms: D000671:Amputation, Surgical / Q000639:trends; D006801:Humans; D007511:Ischemia / Q000401:mortality / Q000601:surgery / Q000628:therapy*; D007866:Leg / Q000098:blood supply*; D015201:Meta-Analysis as Topic; D016896:Treatment Outcome; D014945:Wound Healing