- Sample size calculation: Primary outcome of return to normal activities within 3 days of discharge. Based on previous studies, it is estimated that 70% of the control group will achieve this goal. Based on a minimum absolute difference of 15%, and a power of 0.80, the sample size calculated to be 117 in each arm. Assuming 20% lost to follow up, it is intended to recruit 150 in each arm (total 300 subjects).