Assumptions used in estimating a population benchmark

The assumptions used in estimating a population benchmark rate for new referrals into a faecal continence service are based on the following sources of information:

• epidemiological data on the prevalence of faecal incontinence (FI)
• activity data to establish current rates of surgery for the treatment of FI
• current practice on the current detection rate of FI
• expert clinical opinion of the topic-specific advisory group, based on experience in clinical practice and literature review.

Epidemiological data

It is very difficult to define a robust benchmark based on the true incidence for FI because the true incidence of FI is not known.

There is a range of prevalence estimates for FI in the adult population. This is caused by several factors, including different study populations, different ways of defining FI, different types of measurement and different survey methods used. Estimates based on symptoms of FI can range between 1% and 17%^[1].

The prevalence estimates of FI with impact on quality of life may provide a better indication of the need for services than those based on symptoms alone. This is because many people who have episodes of FI are unlikely to report it to their GP until the symptoms produce a considerable impact on their quality of life.

Perry and co-workers (2002)^[2] estimated that the prevalence of FI with impact on quality of life was 1.4% of the population aged 40 years or more, whereas the prevalence of any FI was around 2%. Figure 1 illustrates the age-specific prevalence of FI by severity, disability and request for help. Research from Edwards and Jones (2001) suggested that less then 50% of people aged 65 years or older with FI had discussed the problem with a healthcare professional in the past 2 years^[3].

Activity data - ‘Hospital episode statistics' data

The ‘Hospital episode statistics' (HES) database contains details of all admissions to NHS hospitals in England. It includes private patients treated in NHS hospitals, patients who were resident outside England and care delivered by treatment centres (including those in the independent sector) funded by the NHS.

Surgery may be indicated for a minority of people with FI. It has been suggested that sacral nerve stimulation (SNS) might become the treatment of choice in patients with FI that has not responded to conservative management^[4].

The NICE costing report for CG49 on faecal incontinence states that following implementation of NICE clinical guideline CG49 on faecal incontinence, SNS may be used in preference to sphincter repair for a percentage of patients who currently receive sphincter repair procedures.

In 2006/7 the mean rate of episodes of SNS for FI was around 4 per million population, and the rate for sphincter surgery for FI was around 20 per million population.

It can be assumed that an increase in patients receiving treatment for FI would be reflected in an increase in SNS, although quantifying the additional numbers is subject to a high degree of uncertainty.

Current practice

IMS Disease Analyser is a database that holds data from a sample of GP practice systems. Data were extracted to give a snapshot of 1 year's activity within general practice.

Results of analysis of these data suggest that around 0.1% of the adult population (aged 15 years or over) come into contact with GP services per year and have FI recognised. This is likely to be an underestimate because some people who experience episodes of FI as a symptom of some underlying conditions may not have the FI recorded in their medical records. Moreover, the topic-specific advisory group considered that older people with many comorbidities are unlikely to have FI recorded on their GP medical records.

Expert clinical opinion

The consensus opinion of the topic-specific advisory group was that:

• There is considerable under recognition and recording of FI in primary care, in particular among those with multiple comorbidities.
• Based on clinical practice an average of around 0.1% of the adult population may present to services and may require specialist intervention such as referral to a continence service (this will require investigation at a local level). However, the numbers presenting to services who may require a baseline assessment and initial management are likely to be much higher.
• The use of focused baseline assessments and active case finding may result in an increase in the detection rate of FI in the community. The estimation of this potential increase is subject to a high degree of uncertainty. However, based on clinical practice and prevalence levels of felt need in the community it should be possible to increase the detection of FI several fold.
• Communities with a higher number of residential and nursing homes are likely to have a higher prevalence of FI with significant unmet need.

Conclusions

Based on the epidemiological data and other information outlined above, it is concluded that the rate of new referrals into a specialist faecal continence service is 0.1% or 100 per 100,000 adult population, per year. This is based on the following assumptions:

• the prevalence of FI in the community population aged 40 years or more is approximately 2%
• the rate of annual detection of new cases requiring referral to a specialist continence service based on current clinical practice could be around 0.1%.

Therefore the population benchmark for new referrals of people with FI into a specialist continence service is estimated to be 0.1%.

Use the faecal continence service commissioning tool to determine the level of service that might be needed locally and to calculate the cost of commissioning the service using the indicative benchmark and/or your own local data.

References

1. Ratto C, Doglietto G, editors (2007) Faecal incontinence: diagnosis and treatment. Milan, Italy: Springer-Verlag.

2. Perry S, Shaw C, McGrother C et al. (2002) Prevalence of faecal incontinence in adults aged 40 years or more living in the community. Gut 50: 480-4.

3. Edwards NI, Jones D (2001) The prevalence of faecal incontinence in older people living at home. Age and Ageing 30: 503-7.

4. Maslekar S, Gardiner A, Maklin C et al. (2006) Investigation and treatment of faecal incontinence. Postgraduate Medical Journal 82: 363-71.