Introduction

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Urinary incontinence is physically debilitating and socially incapacitating, with loss of self confidence, feelings of helplessness, depression, and anxiety all related to its occurrence. ^{1 2} The prevalence among women increases during young adult life: a recent study of over 40 000 women in the community estimated a prevalence of 13% in women aged 18-22, about 35% in women aged 40-74.³

A recent report estimated that 1 835 628 women in the community older than 18 had urinary incontinence in 1998, which incurred a total annual cost of A$710.4m (£257.7m, US$367.4m, 422.5m).⁴

Although studies have proved that conservative treatment of urinary incontinence is effective, we could find no studies on preventing incontinence before its symptoms become evident. ^{5 6} Epidemiological studies have shown an association between more severe forms of urinary incontinence and assisted vaginal deliveries or deliveries of infants with a high birth weight, which suggests the potential for an intervention promoting continence that is targeted at women who have just given birth. ^{7 8}

Our study aimed to test the effectiveness of a programme for preventing urinary incontinence in women at three months after delivery.

	Methods

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We conducted a randomised controlled trial in the postpartum wards of three hospitals between August 1998 and February 2000 in the Hunter region, New South Wales, Australia. Women were eligible to join if they had had forceps or ventouse deliveries or their babies had had a birth weight of 4000 g or more.

Development of the intervention
The intervention was multifaceted and is shown in the figure. The intervention was underpinned by the framework of the health belief model (http://hsc.usf.edu/~kmbrown/Health_Belief_Model_Overview.htm), included strategies to improve compliance, and was developed by using a consensus of expert opinion and input from women in the target group. ^{9 10}

View larger version (41K): [in this window] [in a new window]   Components of intervention promoting continence

Collection of baseline data in hospital
Eligible women were approached on the ward by one of three physiotherapists, usually within 48 hours of delivery. Consenting women completed a structured interview that elicited information on sociodemographics and experiences of urinary incontinence before the pregnancy and after delivery. After this, women were randomised to either a control group receiving usual care or the group receiving the intervention.

Intervention group
The women randomised to the intervention group were seen by the physiotherapist once during their stay in hospital and 306 women were seen again for a single visit with the same physiotherapist at eight weeks after delivery. The components of the eight week intervention are shown in the figure. The intervention in hospital required about 20 minutes of the physiotherapist's time, and the follow up visit was completed in about 30 minutes.

Usual care group
The usual care group received routine postpartum care, which did not include a visit from a physiotherapist. A brochure produced by the hospital was made available to all these women while in hospital. This outlined general postpartum and pelvic floor exercises, along with an invitation to join the routine physiotherapy postnatal classes held in the wards.

Follow up survey
All participants were interviewed by telephone three months after their recruitment into the study. The interviewer was blind to the group allocation of the women being interviewed.

	Measures

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Primary end point
The primary end point for the study was urinary incontinence at three months measured as a dichotomous variable. In the follow up survey women were asked, "In the past month have you:

• leaked even small amounts of urine when you were coughing, sneezing, laughing, or lifting;
• gone to the toilet urgently for fear you would leak;
• leaked even small amounts if you had to wait to use the toilet;
• leaked even small amounts on your way to the toilet; or
• leaked even small amounts if you hadn't gone to the toilet immediately you first felt the need."

They were classified as incontinent if they responded "occasionally," "often," or "always" to any of the items.

Secondary end points
We categorised severity of incontinence as slight, moderate, or severe.¹¹ Women were asked if they were performing pelvic floor exercises ("never," "less than once weekly," "about once a week" (categorised as inadequate levels), "a couple of times a week," "daily," or "more than once a day" (categorised as adequate levels).

Confounders
The following variables were considered as potential confounders and recorded accordingly: age; body mass index; urinary incontinence since the baby was born; perineal status (intact, graze, tear, tear with sutures, episiotomy, episiotomy and tear); joint hypermobility; abdominal striae; type of delivery (instruments used or not).

Data analysis
Logistic regression, using continence status at three months as the outcome measure and including the intervention group as a predictor variable, determined the effect of the intervention while controlling for any residual confounding from variables specified a priori. Mantel-Haenszel ² statistics were used to test for a significantly increasing trend in the proportions of women exercising at adequate levels between the intervention and control groups.

	Results

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During data collection, 913 women were approached and 720 consented to take part. Age, number of pregnancies, marital status, and education of women in the control and intervention groups was similar. The table shows the factors identified a priori as potential confounders for the study in each of the groups. Compared with Australia's perinatal statistics, except for number of births and education, the sample characteristics are similar to the national norms. Compared with the national statistics, our sample had a higher proportion of primiparous women (54% v 40%) and a lower proportion of women with four or more births (5% v 10%).

Retention of women in the study
Between being seen in hospital and the follow up telephone call at three months, 22 women (6%) dropped out of each of the intervention group and the control group. Sixty four women in the intervention group did not attend the follow up visit at eight weeks. As we are analysing by intention to treat, these 64 women were included in the outcome analyses.

Continence status at three months
At three months post partum, the prevalence of incontinence in the intervention group was 31% (108) and in the usual care group 38% (125) (crude odds ratio 0.72 (95% confidence interval 0.52 to 0.99, P=0.044)). After residual confounding was controlled for, the odds ratio of incontinence for women in the intervention group compared with the control group was 0.65 (0.46 to 0.91, P=0.01). The experience of incontinence before the most recent pregnancy and continence status immediately after delivery also had an independent significant effect on continence status at three months (see bmj.com).

At three month follow up a significantly lower proportion of women who had mixed symptoms (symptoms of stress incontinence together with symptoms of urge incontinence) had severe symptoms in the intervention group than in the control group (10% (35 women) v 17% (55 women); a difference of 7% (2% to 12%) (P=0.01).

Adherence to pelvic floor exercises
In the usual care group 189 women (58%) and in the intervention group 292 women (84% of women reported performing pelvic floor exercises at adequate levels (difference 26%, 20% to 33%, P<0.001).

	Discussion

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Potential limitations
Firstly, the results of the main effects of the intervention are of marginal statistical significance, with comparatively wide confidence intervals. When residual confounding was controlled for in the logistic regression, however, the strength of the association increased slightly. Secondly, we need to consider the external validity of the study, as the sample was drawn from only three hospitals. But these hospitalsurban public, urban private, and ruralserved diverse population groups. Thirdly, the response rate indicated that only just over half of women who might have participated in the study actually did so (see bmj.com). The fact that women were missed is a reflection of current practice in many maternity hospitals in Australia. Women are encouraged to leave hospital within hours of delivery, with home support provided by visiting midwives; women with private health insurance usually choose to convalesce in private hospitals.

Women were not blinded to whether they were in the intervention or the control group. They were, however, explicitly told that the study was not measuring their personal individual exercise practice in any punitive fashion but rather whether the intervention helped them to remember to do their pelvic floor exercises. In spite of this, women might have felt socially pressured to admit to exercise levels above those that they performed. Another consideration is that levels of pelvic floor exercise were measured by using self report, which could lead to social desirability bias in the intervention group. There are, however, few, if any, alternatives for monitoring the performance of this type of exercise accurately.

Strengths of the study
The study also had several strengths. Firstly, we used a randomised controlled design. Secondly, the sample size was sufficient to detect a difference of around 8% between groups as significant. Randomised controlled trials are highly idealised and do not mirror real clinical practice. As this study set out to examine how effectively the exercise programme was adhered to, the lack of adherence to exercise by the women in this study gives a realistic outcome that mirrors the potential for the performance of pelvic floor exercises among women who have recently given birth.

Implications
Many women experienced incontinence after delivery. The data from the usual care group show a prevalence of urinary incontinence of 38% among women who had forceps or ventouse deliveries or whose babies had a birth weight of 4000 g or more. It is likely that the intervention was successful because it was based on established theories of behaviour change, incorporated known principles of anatomy and physiology, and included input from consumers in its development. Since dropout rates have been shown to be high among postpartum women performing pelvic floor exercises, the use of behavioural principles seems to have encouraged adherence to the exercise programme and the performance of such exercises. That the programme was designed to exercise specific muscles and fit in with the normal daily routine of the women may have added to its acceptability. The effect of these components in women who have given birth needs to be studied in the longer term, and follow up assessment is planned at 12 months post partum.

If this programme was disseminated among and taught to women by physiotherapists, this could result in the promotion of continence in the wider population. Other health professionals such as midwives and primary care physicians could be trained to carry out the different parts of the interventionmidwives immediately after the delivery and physicians or midwives at a postpartum visit.