Epidemiology of incontinence and prolapse

Authors


Dr C.J. Mayne, Leicester General Hospital, Gwendolen Road, Leicester, UK.

BACKGROUND

In 1954 Nemir and Middleton1 reported that 52% of single nulliparous college students suffered from mild incontinence. More recently, in 1993, a MORI2 poll found that one in seven women over the age of 30 suffered from urinary incontinence and on this basis they estimated that over 2.5 million women in the UK had this problem. It was with this background information that the Leicester Medical Research Council (MRC) Incontinence Study was developed.

The Leicester MRC Incontinence Study was a programme of five interconnecting studies, jointly funded by the MRC and the NHS. The aims of this study were to assess the epidemiology of urinary symptoms, to evaluate existing health provision, to undertake an economic evaluation of urinary disorders, to evaluate new models of health service provision, and to evaluate conservative treatment of urinary disorders. A quarter of a million postal questionnaires were sent to community dwelling men and women aged 40 and over in the Leicestershire area. Names and addresses were taken from general practitioner (GP) registers and 80% of GPs in Leicestershire participated in this study. The overall response rate was 65% and a separate evaluation of the nonresponders was undertaken to try and identify any potential differences between the two groups. The data presented are based on the analysis of the responders' questionnaires.

LOWER URINARY TRACT SYMPTOMS

Figure 1 shows the prevalence of urinary symptoms in men and women over the age of 40. It can be seen that there is an increase in the prevalence in both sexes related to age, but at all ages prevalence in women is greater than in men. The storage abnormality symptoms of hourly frequency, nocturia (greater than three times a night) and urgency are very similar for men and women. However, the prevalence of leakage in women is over twice that of men. In women over the age of 40, the prevalence of storage abnormality symptoms rises from 22% to 45%, and in men over the same age range from 8% to 49%. In both groups there is a tendency for the number of storage abnormality symptoms to increase with age. Using these definitions, the study identified the prevalence of clinically significant symptoms as 26.6% in men and women over the age of 40. This would suggest that within a typical GP list (approximately 1000 people aged over 40) there would be 88 men and 140 women suffering from storage abnormality symptoms. The health economic impact of these findings could be considerable if taken at face value. However, if men and women were asked to state whether or not their storage abnormality symptoms were bothersome, then this figure dropped to only 3.8%. It is likely that this more closely reflects the need within the community but excludes those in residential care.3

Figure 1.

Prevalence of urinary symptoms in men and women over the age of 40.

REPRODUCTIVE FACTORS

In women over the age of 40 the prevalence of urinary incontinence rises almost lineally from 12% in nulliparous women to 26% in women who have had five children. Urgency, nocturia and frequency only increase significantly with parities of three or greater, as does the overall prevalence of faecal incontinence. Following childbirth some women will complain of severe faecal incontinence, which was not identified in nulliparous women. Twenty-one per cent of women reported having had a forceps delivery and this was associated with mild faecal incontinence with an odds ratio of 1.5 after adjusting for age and parity. However, there was no association with urinary incontinence, voiding pattern abnormality, urinary urgency or severe faecal incontinence in women who had had a forceps delivery. Eight per cent of women had undergone a Caesarean section delivery and after adjusting for age and parity, there was a negative association of stress incontinence with an odds ratio of 1.4, but there was no association with urge incontinence, voiding pattern abnormality, urinary urgency or faecal incontinence. A total of 4.16% of the women studied had undergone a hysterectomy and these women were more likely to complain of urinary incontinence. Stress incontinence, urge incontinence and mixed incontinence are significantly more likely to be reported in women who had undergone hysterectomy than in those who had not. They were also more likely to complain of frequency, urgency and nocturia. The odds ratios for these symptoms following a hysterectomy when adjusted for age and parity are shown in Table 1.5

Table 1.  Symptoms reported by women who had undergone a hysterectomy (corrected for age and parity).
 Odds ratioP-value
Severe urinary incontinence1.260.002
Urge incontinence1.49<0.0001
Stress incontinence1.380.0003
Urgency1.610.0002
Frequency1.300.03
Nocturia1.450.003
Severe faecal incontinence1.600.0015

SERVICE USE

When men and women over the age of 40 are asked who they spoke to about their urinary symptoms, the majority stated that they still use their GP as the first professional contact. It has previously been acknowledged that urinary incontinence is one of the so-called ‘latch-key’ problems that patients will only mention at the end of a consultation for something different. Many women are embarrassed by their symptom or feel that it is their ‘lot in life’ to suffer in the same way that their mothers and grandmothers have done before them. The results from that first professional contact are therefore disappointing, with 30% of women being told by their GP to return if their symptoms got worse, and 26% of women being given antibiotics even though there were no other symptoms of urinary tract infection. This would suggest that there is considerable scope for education of all healthcare professionals in the management of urinary incontinence.

EPIDEMIOLOGY OF PROLAPSE

Despite estimates that 20% of women on gynaecological waiting lists are awaiting surgery for prolapse, and 13% of hysterectomies are undertaken because of prolapse, there are few epidemiological studies. This is probably because of the difficulty in defining terms in prolapse assessment, although this might improve if the International Continence Society POPQ staging system becomes more widely used. Also, long-term follow up is required in any proposed study.

Perhaps the best study of the epidemiology of prolapse comes from the Oxford Family Planning Association Study,6 which was set up to monitor the health of women using different contraception. Recruitment occurred between 1968 and 1974, and involved 17 family planning clinics. There were 17,032 women aged between 25 and 39 years recruited to the study, and they were followed up annually until July 1994. Although, as previously indicated, this study was initially set up to evaluate different contraception some analysis was undertaken of women admitted to hospital with prolapse. During the study period 597 women developed prolapse giving an incidence of 204 per thousand person years, of these 473 women underwent surgery for their prolapse. The study identified the major risk factor for prolapse as being parity, following the birth of her first child a woman was four times more likely to develop a prolapse. This risk then rose to 11 times with four or more deliveries.

There is considerable current interest in the problem of prolapse following hysterectomy. The Oxford study identified 2233 women who underwent hysterectomy. Analysis of this group showed that the risk of subsequent surgery for prolapse was 2.9 per thousand person years overall, but it rose to 15.8 per thousand person years if the hysterectomy had originally been performed for prolapse. In addition there was a linear increase in risk over time of women presenting with a prolapse following a hysterectomy.

It can be clearly seen, from what has previously been written, that epidemiology can increase our understanding of incontinence, identify areas for service provision and highlight areas for future research.

Ancillary