Twelve studies (n=13,319) were included. Three studies (n=621) assessed nitrofurazone-coated silicone catheters and 9 studies (n=1,739) assessed silver-coated latex catheters.
Study quality: None of the studies reported the use of intention-to-treat analyses. Four of the 12 studies used alternation to randomise patients, although the actual method of randomisation was not reported by most of the trials; only one study reported the use of a computer-generated randomisation list. Eight studies had uncertain allocation concealment and four had no allocation concealment. Three studies were double-blind; other studies did not clearly report blinding. Three studies reported post-randomisation exclusions and these ranged from 21 to 27%.
Symptomatic urinary tract infections: No studies reported on urinary tract infections associated with catheter use.
Bacteriuria: Five of the 12 studies reported a statistically significant reduction in catheter-related bacteriuria associated with antimicrobial catheters. When the results were stratified by catheter type and publication year, all four pre-1995 studies of silver-coated catheters demonstrated statistically significant reductions in the risk of bacteriuria in favour of the silver-coated catheters, whereas only one of the five post-1995 studies of silver-coated catheters demonstrated a statistically significant result in favour of silver-coated catheters. The other studies reported no statistically significant difference between catheters. None of the three nitrofurazone catheter studies reported a statistically significant difference between catheters.
Antimicrobial activity: Eight studies had details of the microorganisms causing bacteriuria. None of the three nitrofurazone studies found any statistically significant difference between catheters for bacteremia-associated Gram-negative bacteriuria. Two of three evaluable pre-1995 silver-coated catheter trials found that silver catheters were associated with a statistically significant reduction in Gram-negative bacteriuria; the third study found no statistically significant difference between catheters. One of the three evaluable post-1995 silver-coated catheter studies found that the silver catheter lacked preventive activity against Gram-negative bacilli; the other two reported no statistically significant difference between catheters. None of the studies reported on the susceptibility of microbial isolates (urine or other) to the test antimicrobial compound.
Adverse effects: One nitrofurazone study reported that six test and one control catheter patients had a burning sensation. One control patient in a silver-coated catheter study experienced penile pain, and in another silver-coated study approximately 5% of the patients in each group developed haematuria. Another silver-coated catheter study reported urinary tract infections as an adverse event in five patients, but it was unclear which catheter group these related to, or how urinary tract infection was defined.