Critical Appraisal “Frequency and Prevention of symptomless deep-vein thrombosis in long-haul flights: a randomised trial” Group 8

Case Illustration A Couple, Men and women , 55 yo want to travel with economy class airplane and flying time > 8 hours. They heard that long-haul travel can causes symptomless DVT and consult to you about class I elastic compression stocking which can prevent the disease. What should you do as a doctor?

PICO P : men and women 55 yo, economy class airplane passengers, flying time > 8 hours I : class I elastic compression stocking C : passengers who did not wear stocking O : prevent the development of DVT

Clinical question In men and women 55 yo who travel long-haul economy class airtravellers > 8 hours, does the use of class I elastic compression stocking prevents the development of DVT compared to those who do not use compression stockings?

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 patients to treatments randomised? And was the randomisation list concealed? - YES, in page 1486, first line in paragraph which entitled “Randomisation” : “ Volunteers were randomised by sealed enveloped to one of two groups” Were all patients who entered the trial accounted for at its conclusion? And were they analysed in the groups to which they randomised - Yes, in page 1486, Part of method which entitled Trial profile said that “All other analyses were done on intentention to treat basis, ehich included all randomised participant” and they analysed in the group which they randomised, look the chart in page 1486 explain it.

Validity? Were patients and clinicians kept “blind” to which treatment was being received? - No, in title “randomisation” said that “...the passengers were aware of the treatment. Clinician also know about treatment but investigators especially who undertaken duplex examination unaware. Aside from the experimental treatment, were the groups treated equally? - Yes, in page 1486 entitled method part evaluation “ Passengers reattended the Stamford Hospital within 48 h of their return flight...“ and in Result page 1487 paragraph 2 line 1: “The characteristic of two groups were closely matched..”

Validity? 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 man 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 the therapeutic trial valid? VALID

Randomised trial? Important Relative Risk Reduction Absolute Risk Reduction Number Needed to Treat Control Event Rate Experimental Event Rate CER - EER 1/ARR 12/116=10,34% 0/115=0% 10,34-0=10,34% 1/10,3=9,67=10 95% CI = 10,34 ±5,5= (4,8%-15,8%)

Can you apply this valid, important evidence about a treatment in caring for your patient? Is your patient so different from those in the trial that its results can’t help you? No, if inclusion and exclusion criteria match with our patient, we can apply this research. And our patient similar so it’s supposed to be apply.

Can you apply this valid, important evidence about a treatment in caring for your patient? How great would the potential benefit of therapy actually be for your individual patient? Method I: f f =1, so NNT/f=10/1=1 Method II: 1/(PEERxRRR)

Are your patient’s values and preferences satisfied by the regimen and its consequences? Do your patient and you have a clear assessment of their values and preferences - Yes Are they met by this regimen and its consequences? It’s depends on how you explained about this treatment to your patient so patient can decide.

THANK YOU