One hundred fifty Hickman right atrial catheters were inserted into 143 patients and were followed prospectively until removal. Primary indications for their use were: cancer chemotherapy (45), parenteral nutrition (35), antibiotic therapy (63), and miscellaneous (7). The overall catheter-associated infection rate was 12.0%. Since the mean duration of catheterization was 125 days, the infection/duration rate was 1.0/1,000 days of use. The risk of infection differed significantly according to the primary indication for catheterization: parenteral nutrition > antibiotic therapy > cancer chemotherapy. The increased risk of catheter-associated infection attributable to duration of catheterization was additive, and the per day risk of such infections remained constant regardless of duration. Nearly two-thirds of patients were discharged home with catheters in place, without adversely affecting infection risk.

Nosocomial infection rates, as determined by either incidence or prevalence methods, are considered important data in infection control programs. Many factors besides infection control measures affect infection rates— eg, illness acuity of the patient population. However, there is evidence that when these factors remain constant, a lowering of the infection rate can be the result of infection control efforts. We wish to illustrate how a dramatic drop in infection rate may mislead infection control personnel into a false sense of accomplishment, when in reality it is an effect of changing medical practices.