Objective: To estimate the relation of smoking status and smoking intensity with bladder symptoms.
Methods: Questionnaires were mailed to 3,000 women (aged 18-79 years) randomly identified from the Finnish Population Register. Case definitions for stress urinary incontinence (SUI), urgency, and urgency urinary incontinence (UUI) were "often" or "always" based on reported occurrence (never, rarely, often, always). Case definitions for urinary frequency were based on reporting of longest voiding interval as less than 2 hours and for nocturia reporting of at least two voids per night. Potential confounders included comorbidities, medications, sociodemographic, lifestyle, and reproductive factors.
Results: Responses totaled 2,002 (67.0%). Frequency was reported by 7.1%, nocturia 12.6%, SUI 11.2%, urgency 9.7%, and UUI 3.1%. In the multivariable analyses, smoking was associated with urgency (odds ratio [OR] 2.7, 95% confidence interval [CI] 1.7-4.2 for current and OR 1.8, CI 1.2-2.9 for former compared with never smokers) and frequency (OR 3.0, CI 1.8-5.0 for current and OR 1.7, CI 1.0-3.1 for former smokers) but not with nocturia and SUI. Adjusted prevalence differences between never and current smokers were 6.0% (3.0-9.1%) for urgency and 6.0% (3.3-8.7%) for frequency. Similarly, current heavy (compared with light) smoking was associated with additional risk of urgency (OR 2.1, CI 1.1-3.9) and frequency (OR 2.2, CI 1.2-4.3).
Conclusion: Urgency and frequency are approximately three times more common among current than never smokers. Parallel associations for urgency and frequency with smoking intensity suggest a dose-response relationship. Nocturia and SUI are not associated with smoking. These results suggest an additional rationale for smoking cessation in women seeking medical attention for bladder symptoms and highlight the diversity between such symptoms.
Level of evidence: II.