Reasons for replacement of long-term urethral catheters: implications for randomized trials.

On any given day more than 100,000 nursing home patients have indwelling urethral catheters in place. We prospectively followed 47 such patients for almost 18 patient-years and observed 249 catheter replacements. The mean number of replacements per 100 days of catheterization was 3.1 (71% of the catheters were replaced within 30 days of insertion). Nonprescribed removal by the patient or nursing staff was the most frequent cause of replacement (43%), followed by leakage (33%) and obstruction (24%). Catheter replacements followed patient-specific patterns, with each reason for replacement being associated significantly with the reason for the prior replacement (p less than 0.001). To minimize the effect of patient-specific replacement patterns, studies of complications of catheterization that may be affected by catheter obstruction or replacement should use cross-over designs.