<qa>  What was the rate of catheter-related bloodstream infection of the group with heparinSTATISTICAL ANALYSIS Calculation of the required sample size was based on main outcomes. It was assumed that the group with heparin lock would have a rate of catheter-related bloodstream infection of 150 greater than that of catheters with TCS30 lock. With a two-sided test, and an alfa error of 5 and 80 of power, it was required 112 catheters for each group. 