The impact of open access flexible sigmoidoscopy

The impact of open access flexible sigmoidoscopy: a comparison of two services

P.J. ARUMUGAM*, G.N. RAO†, J. WEST†, M.E. FOSTER†# and P.N. HARAY*#
*Prince Charles Hospital, Merthyr Tydfil, †East Glamorgan General Hospital, Pontypridd, # External Professor, School of Care Sciences, University of Glamorgan, Pontypridd, Wales

Introduction

Discussion

Background: Open access flexible sigmoidoscopy (OAFS) is an integral part of colorectal cancer services. This study compares the impact of two types of open-access flexible sigmoidoscopy services on the utilisation of barium enema and tumour-stage migration. Method: This was a non-randomised comparison (over two one-year periods, four years apart) of two unselected groups of patients, with different inclusion criteria, in adjacent similarly populated health districts. One offered a nurse practitioner endoscopy service while the other had a doctor-led colorectal clinic. Results: The doctor-led service with its broad inclusion criteria detected more colorectal cancers [13.2% versus 0.7%; OR = 16.05; 2.16 - 119.2]. Neither nurse practitioner (130 cases) nor doctor-led (262 cases) flexible sigmoidoscopy reduced the total number of barium enemas [Odds Ratio (OR) = 1.16 (95% CI 1.03-1.3)]. However, the doctor-led service did reduce the number of barium enemas requested by general practitioners (from 249 to 152). The total number of colorectal cancers (detected by all available methods) were similar [OR=0.82 (0.53-1.25)] and both services resulted in a similar tumour-stage migration [OR=1.39 (0.31-6.23)]. Conclusion: Open access flexible sigmoidoscopy services have minimal impact on the utilisation of radiology services. Broader inclusion criteria of doctor-led services produce a higher cancer-yield. Tumour-stage migration may be related to greater awareness of colorectal cancer symptoms rather than to the type of OAFS.

Keywords: Barium enema, colorectal cancer, general practitioner, nurse-practitioner open-access flexible sigmoidoscopy

Twenty-five percent of patients with rectal bleeding have colorectal neoplasms (carcinoma and polyps).¹ Full investigation of all rectal bleeding will fail to reveal any abnormality in 50% of cases.² This can cause considerable strain on health resources if every case of rectal bleeding underwent colonoscopy and/or barium enema. Open access flexible sigmoidoscopy (OAFS) (either as a one-stop rectal bleeding clinic or as a nurse practitioner diagnostic service) is a relatively safe solution and is now considered the first line investigation in most cases.² Total colonoscopy and/or barium enema is best reserved for high-risk cases and for those with persistent symptoms after a negative flexible sigmoidoscopy. Of the two types of OAFS services, patient-satisfaction and diagnostic-yield with the nurse practitioner service is comparable with a doctor-led service.³ This would perhaps represent a logical cost-effective way forward.

Referral criteria for the open-access service depend on available manpower and resources. Obviously, the broader the criteria, the greater the pick-up rate of significant pathology, regardless of whether the service is provided by nurses or doctors.

This study assesses the impact of two types of (OAFS) service on the use of barium enema and on tumour stage migration.

This study represents a prospective non-randomised comparison of two unselected consecutive series of patients (in two adjacent health districts), undergoing open access flexible sigmoidoscopy with different inclusion criteria. The study periods were two twelve-month periods from1 Jan 1993 to 31 Dec 1993 (with no access to flexible sigmoidoscopy service in either district) and from 1 July 1997 to 30 June 1998 (when an open access service was established in both districts).

District 1 employed a nurse practitioner open access service utilising minimal admission criteria (age >45 years and fresh rectal bleeding). The adjacent health district (District 2) used a doctor-led service utilising one or more of all possible criteria (rectal bleeding; weight loss; altered bowel habit; positive family history). Population served by both health districts was similar (190,000 for District 1 and 170,000 for District 2). The nurse practitioner open access flexible sigmoidoscopy was introduced in 1996 after a senior endoscopy nurse practitioner was trained in accordance with approved guidelines.4 The doctor-led service was established in 1997-98 in District 2. During the study period of 1997-98, general practitioners in both districts had the option of sending their patients with rectal bleeding for either an open access barium enema or an open access flexible sigmoidoscopy.

We have compared these two services by evaluating their effect on the number of barium enemas performed, diagnostic yield of colorectal cancers and any effect on stage-migration of colorectal cancers. It was not our intention to compare the diagnostic yield of polyps, because this is an issue being studied by the current multicentre population-screening studies.

During 1993, the relevant data was collected prospectively as part of the Welsh-Trent audit, while during 1997-98, data was collected prospectively from the computerised databases in endoscopy, pathology and radiology departments.

Statistical Methods: Comparison of non-parametric variables was with Odds ratio (95% confidence interval (CI)). Since this study is a prospective non-randomised study on unselected series of patients with possible population differences, an odds ratio of greater than 4.0 with the 95% CI not including 4.0 was considered significant.5 For the assessment of the nurse-practitioner service over two time periods, OR of more than 1.0 was considered significant.

In District 2, using the doctor-led service, there was a small statistically insignificant drop in the number of patients undergoing open access barium enemas from 249 in 1993 to 152 in 1997-98(OR=1.89; 95% CI 1.49 to 2.4). There was an increase in the number of in-hospital requests for barium enema from 877 to 928 (OR=1.16; 1.03-1.3; Figure 1), but the total number of barium enemas was reduced by 46 (statistically insignificant).

In District 1 there was a drop in the total number of cancers detected by all modalities from 87 in 1993 to 84 in 1997-98, whereas District 2 showed an increase from 80 to 94 during the same periods. These differences, however, do not achieve statistical significance (OR=0.92; 95% CI 0.6 to 1.4, Figure 1). The doctor-led endoscopy service in District 2, on the other hand, led to a higher cancer yield in 1997-98 (29 cancers out of 262 endoscopies, 13.2%), compared with 1 cancer detected out of 130 procedures in the nurse-led service in District1 (0.7%). This is statistically significant (OR=16.05; 95% CI 2.16-119.2, Figure 2). Both the districts registered similar stage migration towards the more favourable Dukes' stage A as shown in Figure 3. This is not statistically significant with an (OR=1.39; 95 % CI 0.31 to 6.23). It was noted there was a reduction in the number of patients presenting with Dukes'stage B,C, and distant metastasis (OR=0.87; 95 % CI 0.55 to 1.37, Figure 3).

Figure 1 : This documents the referral pattern in the two districts studied.

Figure 2 :This demonstrates a higher cancer detection rate with a doctor-led service during 1997-98(13.2% vs 0.7%) compared with using a nurse practitioner service

Figure 3: This figure shows that both hospitals demonstrate similar stage migration in the two time periods studied; 1993; 1997-98

Open access flexible sigmoidoscopy leads to increased detection of colorectal cancers.^6,7 While this study demonstrates a similar result, the improved detection rate of colorectal cancers and favourable tumour-stage migration occurred irrespective of whether a nurse practitioner or doctor-led service was used. Furthermore, this increase was similar in both the districts despite the nurse practitioner OAFS detecting a negligible number of colorectal cancers, in comparison with the doctor-led service which detected twelve percent more colorectal cancers. This would suggest that factors other than OAFS might be responsible for the rising numbers of colorectal cancers presenting at an early stage. Perhaps a greater awareness of the colorectal cancer symptoms has led to earlier referral for specialist care and OAFS probably plays only a minimal role in this process.

Nurses have been performing flexible sigmoidoscopy at many centres in the United States,⁸ and a similar trend is beginning to be observed in the United Kingdom. There is no demonstrable difference in effectiveness or patient satisfaction for flexible sigmoidoscopy performed by a registered nurse, general surgeon or a gastroenterologist.3 The aim of a nurse-led service is primarily to reduce the waiting time for diagnostic investigations (thus making it perhaps more cost effective) and secondarily to reduce the outpatient workload. The cancer yield-rate with this service has remained low with no apparent effect on the radiological diagnostic services. This may be due to a reluctance by general practitioners to accept a nurse led service and may also account for the increase in open access barium enemas seen in District 1, in comparison with the decrease noted in District 2 with the doctor-led service. This study has not shown a significant decrease in the utilisation of barium enema. It remains unclear whether this is due to a lower threshold for radiological investigations or due to an increase in the total number of patients being investigated. The true impact of OAFS can only be evaluated by studying the decrease in outpatient and radiological workload.

An open access flexible sigmoidoscopy service is a reflection of a sub-specialist approach in any district and does lead to a favourable stage migration of newly diagnosed colorectal cancers. It is debatable as to whether this is a direct effect of such a service or a part of the overall improvement due to a specialist approach. This study, however, has not shown a significant decrease in the utilisation of existing diagnostic modalities. Whether this is due to a lack of impact of the OAFS service or due to a lowered threshold for investigation, or due to an increase in the total number of patients being investigated, is unclear.

Correspondence: Prof. P.N. Haray, Consultant Surgeon, Prince Charles Hospital, Merthyr Tydfil CF47 9DT, U.K.