Thirty-seven RCTs were included in the review (n=19,434 patients; 12,368 active treatment and 7,066 placebo). Sample sizes ranged from 43 to 1,017. Twenty-six trials did not adequately describe randomisation technique. Methods of blinding were described in 15 trials. Methods of evaluating adverse events were inadequately described or relied on spontaneous reporting in 34 trials. Further individual results were published in a separate online supplement.
The use of anticholinergic agents was associated with a significantly greater rate of constipation in adults with overactive bladder (OR 2.18, 95% CI 1.82 to 2.60; I2=29.4%) compared with placebo.
When stratified by each type of anticholinergic agent, there was still a greater proportion of patients that reported constipation compared with placebo: darifenacin (OR 1.93, 95% CI 1.40 to 2.66; I2=32.6%; six RCTs); fesoterodine (OR 2.07, 95% CI 1.28 to 3.35; I2=0%; three RCTs); oxybutynin (OR 2.34, 95% CI 1.31 to 4.16; I2=0%; seven RCTs); solifenacin (OR 3.02, 95% CI 2.37 to 3.84; I2=49.1%; seven RCTs); tolterodine (OR 1.36, 95% CI 1.01 to 1.85; I2=0%; 10 RCTs); and trospium (OR 2.93, 95% CI 2.00 to 4.28; I2=46.5%; four RCTs).
Significant funnel plot asymmetry was demonstrated for fesoterodine and trospium.