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Table 3.9 shows the results of randomised controlled trial in primary care in patients with venous leg ulcers to compare a new specially impregnated bandage, called ‘Band aid’, with usual care. Usual care will be treatment by district nurses with standard bandages and wound dressings. The primary outcome for the study will be whether or not the index or reference leg ulcer has completely healed at a 12‐month post‐randomisation.

1 3.1 What proportion of patients in the Band‐aid group had a completely healed leg ulcer at 12 months?0.300.400.600.650.70

2 3.2 What proportion of patients had a completely healed leg ulcer at 12 months in the control group?0.300.400.600.650.70

3 3.3 What is the difference in response (leg ulcer healing rates at 12 months) between the Band‐aid and control groups?−0.10−0.050.000.050.10

4 3.4 Calculate the number of people needed to be treated with Band‐aid dressing in order for an additional person to have a completely healed leg ulcer at 12 months compared to people usual care?6 78810

5 3.5 What is the relative risk for the leg ulcer healing at 12 months in the Band‐aid group compared to the control group?0.640.861.171.562.33

6 3.6 What is the relative risk for the leg ulcer healing at 12 months in the control group compared to the Band‐aid group?0.640.861.171.562.33

7 3.7 What are the odds for the leg ulcer healing at 12 months in the Band‐aid group?0.640.861.501.562.33

8 3.8 What are the odds for the leg ulcer healing at 12 months in the control group?0.640.861.501.562.33

9 3.9 Calculate the odds ratio for the leg ulcer healing at 12 months in the Band‐aid group compared to the control group?0.640.861.171.562.33

10 3.10 Calculate the odds ratio for the leg ulcer healing at 12 months in the control group compared to the band‐aid group?0.640.861.171.562.33