Objective: To determine whether there is an association in women between caffeine intake and risk for detrusor instability.
Methods: Women were included if they had symptoms of urinary incontinence, completed a 48-hour voiding diary detailing fluid and caffeine intake, and had undergone standardized multichannel urodynamics. The study group had 131 women with detrusor instability on provocative cystometry and maximum urethral closure pressure greater than 20 cm of water. The control group had 128 women without detrusor instability on provocative cystometry and maximum urethral closure pressure greater than 20 cm of water. For statistical comparison, women were divided into the following three groups on the basis of caffeine intake: minimal (< 100 mg/day), moderate (100-400 mg/day), and high (> 400 mg/day).
Results: The mean caffeine intake of women with detrusor instability (484 +/- 123 mg/day) was significantly higher than that of controls (194 +/- 84 mg/day, P =.002). On univariate analysis, significant risk factors for detrusor instability were age, smoking status, and caffeine intake. On multivariate analysis, the statistically significant association between high caffeine intake and detrusor instability persisted after controlling for age and smoking (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.1, 6.5, P =.018). When women with moderate caffeine intake were compared with those with minimal caffeine intake, the risk for detrusor instability was lower and did not reach significant levels (OR 1.5, 95% CI 0.1, 7.2, P =.093).
Conclusion: An association between high caffeine intake and detrusor instability was seen in this population. Larger studies are required to determine whether the association is causal.