Assumptions used in estimating a population benchmark

The assumptions used in estimating a population benchmark for an endometrial ablation service of 0.058% per year are based on the following sources of information:

• Hospital episode statistics data to establish the current levels of activity commissioned
• published research on the care of women with heavy menstrual bleeding (HMB)
• expert clinical opinion of the topic-specific advisory group, based on experience in clinical practice and literature review.

Activity data - Hospital episode statistics

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 of England and care delivered by treatment centres (including those in the independent sector) funded by the NHS.

Analysis of HES data suggests that the number of endometrial ablation procedures performed for HMB has been increasing since 1997/98, with a sharp rise in more recent years. The number of hysterectomies being performed for HMB within English trusts has been declining since 1994/95^[1].

Figure 1 illustrates the rolling (3-year) averages for the numbers of endometrial ablations and hysterectomies, and the total of the two procedures, performed between 1989 and 2004 (adapted from Reid 2006 with permission).

The fall in the number of hysterectomies for the treatment of HMB is not due to the rise in endometrial ablations alone, as there has been a steady decline in the total number of procedures being performed for HMB^[1]. This decline has plateaued in more recent years.

More recent data for 2005 suggest that in England the annual rate of increase in the number of endometrial ablations over the past 3 years is around 17% each year.

HES data (see figure 2) give an indication of the rates at which endometrial ablations for HMB are being performed. Average rates do not necessarily correlate with the rate that would be expected if NICE clinical guideline CG44 on heavy menstrual bleeding was uniformly followed.

The mean directly standardised rate for endometrial ablations for all English primary care organisations for the year 2005/06 is 46 per 100,000 female population.

The average rate of endometrial ablations hides large variations. Procedure rates vary among primary care organisations from fewer than 10 per 100,000 to nearly 140 per 100,000 female population. Thus, there is a 14-fold variation in rates across England.

Some of the variation in endometrial ablation procedure rates is likely to be due to symptom prevalence, the treatment preferences held by women and other clinical reasons. However, these alone are unlikely to account for all of the variation, and there may be other factors that influence it, such as variations in service capacity and differences in the management of HMB within primary care^[2].

Published research

The relationship between medical management, referral and surgery is complex^[2]. There are wide variations in patterns of referral into secondary care for women with HMB. More effective management of HMB in primary care may reduce the number of referrals into secondary care and surgery rates^[2],^[3].

Active education in relation to good management and the promotion of effective medical management in primary care has been shown to reduce the number of referrals into secondary care by between 30%^[3] and 50%^[4].

A randomised controlled trial^[5] found that the provision of structured information around treatment options for women with HMB resulted in a significant decrease in the number of women who stated a preference for hysterectomy, from 48% to 38%.

A review of women undergoing hysterectomy found that 70% were not offered medical management by their GP and that 39% had a hysterectomy as primary treatment for HMB^[6]. In addition not all women undergoing hysterectomy for HMB are offered endometrial ablation as an alternative where it is clinically appropriate to do so^[6],^[7]; this figure is estimated to be between 50%^[7]and 56% (Owen P, Welsh J: unpublished data 2007). A midpoint of 53% is used below.

A 33% increase in the number of endometrial ablations could be expected if all women undergoing hysterectomy were offered endometrial ablation where appropriate, given that:

• 53% of women undergoing hysterectomy are not offered endometrial ablation as an alternative
• 38% of women may express an explicit preference for hysterectomy when given information around alternative treatment options.

This assumes that all women undergoing surgery first receive optimal medical management including the use of levonorgestrel-releasing intrauterine system (LNG-IUS) devices. Commissioners will need to examine their local care pathways to assess the validity of this assumption.

Expert clinical opinion

The topic-specific advisory group agreed that it is difficult to determine what may happen to rates of endometrial ablation in the future because the effects of LNG-IUS devices such as the Mirena coil on the care of women with HMB are not currently known. The optimal use of this intervention could lead to a reduction in the number of surgical procedures for HMB.

Commissioners will need to examine their own local prescribing and procedure rates to ensure that appropriate levels of endometrial ablation services are commissioned. It is expected that results from the ECLIPSE trial will inform the long-term outcomes of LNG-IUS devices.

Conclusions

Based on the epidemiological data and other information outlined above, it is concluded that the proportion by which endometrial ablation rates may increase is 25%, giving a population benchmark of 0.058% or 58 per 100,000 female population. This is based on the following assumptions:

• the current rate of endometrial ablation for the treatment of HMB is 46 per 100,000 female population
• current trends in the rates of endometrial ablation for the treatment of HMB suggests an increase of 17% per year
• a potential 33% increase in the number of endometrial ablation procedures could be expected, based on published research around patient choice
• the midpoint between the increase suggested by current trends and the increase suggested by published research on patient choice is 25%.

Therefore the population benchmark for endometrial ablation is estimated to be 0.058%.

This benchmark has not taken into account the impact of LNG-IUS on the rate of endometrial ablation, as this is not currently known. Commissioners will need to examine and monitor their own prescribing and activity levels to ensure that the appropriate levels of endometrial ablation are commissioned.

Use the endometrial ablation commissioning and benchmarking 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. Reid PC (2006) Endometrial ablation in England - coming of age? An examination of hospital episode statistics 1989/1990 to 2004/2005. European Journal of Obstetrics and Gynecology

2. Grant C, Gallier L, Fahey T et al.(2000) Management of menorrhagia in primary care - impact on referral and hysterectomy: data from the Somerset Morbidity Project. Journal of Epidemiology and Community Health 54: 709-13.

3. Nixon RM, Duffy SW, Fender GRK et al. (2001) Randomization at the level of primary care practice: use of pre-intervention data and random effects models. Statistics in Medicine 20: 1727-38.

4. Zachariah M, Fender G (2005) Managing menorrhagia in primary care. Women's Health Medicine 2: 17-20.

5. Kennedy ADM, Sculpher MJ, Coulter A et al. (2003) A multicentre randomised controlled trial assessing the costs and benefits of using structured information and analysis of women's preferences in the management of menorrhagia. Health Technology Assessment 7(8).

6. Rahman KM, Onyeka BA (2001) Treatment of menorrhagia before hysterectomy in a district general hospital. A retrospective review. Journal of Obstetrics and Gynaecology 21: 64-6.

7. Ali CR, Suchetha M, Arthur ID (2007) Compliance with published RCOG guidelines in women undergoing hysterectomy in a district general hospital. Journal of Obstetrics and Gynaecology 27: 171-3.