Use of symptom-relieving drugs before and after surgery for urinary incontinence in women: a cohort study

OBJECTIVE: To describe the use of symptom-relieving drugs (antimuscarinic drugs or duloxetine) before and after surgery for urinary incontinence (UI); and for those with use of antimuscarinic drugs or duloxetine before surgery, to estimate the risk of being a postoperative user, relative to those without use before surgery. DESIGN: A historical population-based cohort study. SETTING: Denmark. PARTICIPANTS: Women ≥18 years with a first-time surgical procedure for UI from the county of Funen, Denmark between 1 January 1996 and 31 December 2006, extended to the Region of Southern Denmark from 1 January 2007 to the end of 2010. For these women, data on redeemed prescriptions ±365 days of date of surgery were extracted. MAIN OUTCOME MEASURES: Effect of preoperative use of antimuscarinic drugs or duloxetine on the risk of being a postoperative user of these drugs. RESULTS: Of 2151 women with a first-time surgical procedure for UI, 358 (16.6%) were preoperative users of antimuscarinic drugs or duloxetine and 1793 were not (83.4%). A total of 110 (30.7%) of the preoperative users also redeemed prescriptions for these drugs within 0–60 days after surgery, and 152 (42.5%) of the preoperative users redeemed prescriptions for these drugs within 61–365 days after surgery. Among preoperative non-users, 25 (1.4%) and 145 (8.1%) redeemed prescriptions within 0–60 and 61–365 days after surgery, respectively. Presurgery exposure to antimuscarinic drugs or duloxetine was a strong risk factor of postoperative drug use, both within 0–60 days (adjusted OR=33.0, 95% CI 20.0 to 54.7) and 61–365 days (OR=7.2, 95% CI 5.4 to 9.6). CONCLUSIONS: A substantial number of women will continue to be prescribed symptom-relieving drugs after surgery for UI within a year of follow-up. Only a minority of preoperative non-users initiated usage of symptom-relieving drugs after surgery. Compared with other factors included in the regression model, preoperative use of antimuscarinic drugs or duloxetine was the strongest risk factor for postoperative use.