Frequency and Prevention of Symptomless deep-vein thrombosis In long-haul flights: a randomised trial Grup 4

Case Ilustration A couple, men and women, 55 yo who wants to travel with economic class airplane and flying time > 8 hours. They heard that long haul air travel can cuses symptompless DVT. They consul to a doctor about wearing of elastic compressions stockings during long haul air travel can prevent DVT.

Wearing elastic compression stockings PATIENT/PROBLEM INDICATOR COMPARISON OUTCOME men and women, 55 yo who wants to travel with economic class airplane and flying time > 8 hours Wearing elastic compression stockings Doesn’t wearing elastic compression stockings Prevent symptomless DVT PICO: Does the usage elastic compression stockings on men and women 55 yo who wants to travel with economic class airplane and flying time > 8 hours will prevents the symptomless DVT compared to the people who do not use the the elastic compression stockings? Type of Question: Therapeutic Type of study/methodology: RCT (randomized clinical trial)

Citation Scurr J H, Machin S J, Bailey-King S, Mackie I J, McDonald S, Smith P D C. Frequency and prevention of symptomless deep-vein thrombosis in long-haul flights : a randomised trial. The Lancet 2001; 357: 1485-89.

Validity Was the assignment of patient to treatments randomised? And was the randomisation list concealed Yes, it was. In page 1486 , first line in paragraph : Randomisation :” Volunteers were randomised by sealed envelope to one ef two groups” Were all patients who enterede the trial accounted for at its conclusion? And were they analysed in the groups to which they were randomised?

Were patients and clinicians kept”blind” to which treatment was being received? No, they weren’t. In title randomisation and Evaluation said that : the passengers were aware of the treatment. Clinician know about treatment but the technician who was undertaken duplex examination unaware. Aside from the experimental treatment, were the groups treated equally? Yes, they were. In title Method of Evaluation and Results “ Passengers reattended the Stamford Hospital within 48 h of their return flight. In the “Results” paragraph 2 line 1 said that : the characteristics of the two groups were closely matched.

Were the groups similar at the start of the trial? - Yes, although number of women more in the group stocking, there are no different result between men and women for developing DVT in recent knowledge. (page 1488 first line in second column of paragraph) Are the Results of this single preventive or therapeutic trial valid? Valid

No Stockings Stockings DVT 12 + 16 0 + 15 Non DVT 88 100

Important 95% CI = Relative Risk Reduction Absolute Risk Reduction Number Needed to Treat Control Event Rate Experimental Event Rate CER - EER 1/ARR 28/116=0,24% 15/115=0,13% 0,24-0,13=0,11% 1/0,11= 95% CI =