Hysterectomy and risk of stress-urinary-incontinence surgery: nationwide cohort study

Summary

Background

Hysterectomy for benign indications has been associated with an increased risk for lower-urinary-tract sequela, but results have been inconclusive. We aimed to establish the risk for stress-urinary-incontinence surgery after hysterectomy for benign indications.

Methods

We did a nationwide, population-based, cohort study from 1973 to 2003 in Sweden. We identified our population from the Swedish Inpatient Registry. We selected 165 260 women who had undergone hysterectomy (exposed cohort) and a control group of 479 506 individuals who had not had this procedure (unexposed cohort), matched by year of birth and county of residence. In both cohorts, occurrence of stress-urinary-incontinence surgery was established from the Swedish Inpatient Registry. Hazard ratios with 95% CIs were calculated by Cox's proportional-hazards regression.

Findings

During the 30-year observational period, the rate of stress-urinary-incontinence surgery per 100 000 person-years was 179 (95% CI 173–186) in the exposed cohort versus 76 (73–79) in the unexposed cohort. Correspondingly, individuals in the exposed cohort were at increased risk for stress-urinary-incontinence surgery compared with those in the unexposed cohort (hazard ratio 2·4; 95% CI 2·3–2·5), irrespective of surgical technique. Risk for stress-urinary-incontinence surgery varied slightly with time of follow-up: the highest overall risk was recorded within 5 years of surgery (2·7; 2·5–2·9) and the lowest risk was seen after an observation period of 10 years or more (2·1, 1·9–2·2).

Interpretation

Hysterectomy for benign indications, irrespective of surgical technique, increases the risk for subsequent stress-urinary-incontinence surgery. Women should be counselled on associated risks related to hysterectomy, and other treatment options should be considered before surgery.

Introduction

Hysterectomy is a preferred treatment option in women because of its low perioperative morbidity and effectiveness in bringing a definitive cure to disorders such as menometrorrhagia, leiomyoma, uterine prolapse, adenomyosis, and postmenopausal bleeding.¹ By age 55 years, about one in five British women will have undergone a hysterectomy.² In the USA, 600 000 procedures are undertaken every year,³ of which 90% are done for benign indications.⁴

Large variations exist in rates of hysterectomy between and within countries and between populations with similar characteristics.2, 5 Although health-economic factors and differences in morbidity can account for some of the variation, rates of hysterectomy for benign indications are largely affected by differences in medical practice and attitudes.6, 7 Considering the generally high hysterectomy rates in premenopausal and perimenopausal women,³ increased knowledge of the long-term outcomes associated with undertaking hysterectomy for benign indications is essential.

For decades, the effects of hysterectomy on lower-urinary-tract function have been controversial. One theory suggests that hysterectomy could initiate stress urinary incontinence by interruption of the local nerve supply to the urethra,⁸ and the procedure might cause changes in urethral pressure dynamics by distortion of pelvic-organ anatomy.⁹ Results from many previous studies relating hysterectomy to adverse effects of the lower urinary tract have been inconsistent. The conflicting evidence could be attributed to methodological shortcomings including inadequate statistical precision owing to small sample sizes, scarcity of controls who have not had hysterectomy, short durations of follow up, and systematic errors, such as ascertainment, selection, or recall bias.¹⁰

Female stress urinary incontinence, defined as involuntary leakage of urine on effort or exertion,¹¹ has a population-based prevalence of nearly 40% in most industrialised countries, usually with severe implications for daily function, social interactions, sexuality, and psychological wellbeing.¹² Stress urinary incontinence also has a major effect on health economy¹² and is increasingly recognised as a global health concern.¹³ Identification and possible reduction of risk factors for stress urinary incontinence is, therefore, of importance for women at risk and for society's direct health-care costs. The primary aim of this nationwide, population-based, cohort study was to assess short-term and long-term risk for stress-urinary-incontinence surgery after hysterectomy for benign indications.