title: Knee-length graduated compression stockings for thromboprophylaxis in air travellers: A meta-analysis.
abstract: OBJECTIVE
  To systematically review the randomized controlled trials that have evaluated the efficacy of knee-length (KL) compression stockings for thromboprophylaxis in air travellers.
  
  
  METHODS
  After an electronic database search, the randomized controlled trials that studied passengers on long-haul flights were selected and analyzed to generate summative data.
  
  
  RESULTS
  Nine trials studying participants using KL stockings were analyzed. Forty-six of 1261 participants randomly assigned to the control group developed deep vein thrombosis (DVT), compared with two of 1237 participants (0.16%) in the KL stockings group. The weighted risk difference was -0.034, which indicated that the absolute difference was 3.4% in the incidence of DVT, in favour of KL stockings. The number needed to treat with KL stockings to avoid one case of DVT was 29.4. However, there was significant heterogeneity among trials. The RR for DVT was 0.08 in high-risk participants and 0.14 in low- to medium-risk participants.
  
  
  CONCLUSIONS
  KL stockings are effective for thromboprophylaxis in air travellers at low, medium and high risk of DVT. The use of KL stockings should form an important part of air traveller education on lowering the burden of DVT. The results of the present meta-analysis can be used to advise travellers on their risk of DVT and preventive strategies.
authors.affiliation: Department of Vascular Surgery, Royal Free Hospital, University College, London, UnitedKingdom. surgeon1wrh@hotmail.com
authors.forename: Muhammad Shafique
authors.initials: MS
authors.lastname: Sajid
authors.forename: Mittal
authors.initials: M
authors.lastname: Desai
authors.forename: Richard
authors.initials: R
authors.lastname: Morris
authors.forename: George
authors.initials: G
authors.lastname: Hamilton