Budget-impact model for colonoscopy cost calculation and comparison between 2 litre PEG+ASC and sodium picosulphate with magnesium citrate or sodium phosphate oral bowel cleansing agents

Figures & data

Table 1.  Variable inputs from audit data collected from St. Georges Hospital, London into the budget impact model questionnaire plus drug acquisition costs without fixed costs.

Model questions	Source	Answer
About sessions and procedures
On average, how many procedures (upper and lower endoscopy) are performed each week?	Audit	100
On average, how many colonoscopy procedures are performed per week (excluding emergencies)	Audit	50
In weeks, what is your current colonoscopy waiting list?	Audit	0
On how many weeks per year do you perform endoscopies?	Audit	48
About the most frequently used bowel preparation for colonoscopy
Which is your most commonly used bowel preparation product?	Audit	NaPic + MgCit
On average, how many colonoscopy patients will be prepared for colonoscopy using Picolax every week?	Audit	50
For the total no. of colonoscopy patients who receive Picolax what percentage are in-patients (not including persons admitted specifically for bowel preparation)?	Audit	10.0%
What percentage of out-patients undergoing colonoscopy do you admit for supervised administration of Picolax (e.g., who are frail, have renal insufficiency, or have other problems such as diabetes)?	Audit	3.0%
On average, how many nights before the procedure are patients from previous question admitted?	Audit	1
The cost of Picolax for one treatment is	MIMS	£3.52
For your in-patients what percentage of procedures are having to be repeated due to poor visualization?	Audit	56.0%
For your out-patients what percentage of procedures are having to be repeated due to poor visualization?	Audit	5.0%
Currently does your unit participate in performing colonoscopies as part of the National Bowel Cancer Screening Programme?	Audit	Yes
Currently, or in the future what are your expected annual numbers of patients that will require colonoscopy in your unit as a result of participating in the national Bowel Cancer Screening Programme?	Audit	20
PEG + ASC
Given the information you have been supplied about PEG + ASC, what percentage of patients undergoing colonoscopy would you expect to admit for supervised administration of PEG + ASC (e.g. who are frail, have renal insufficiency, or have other problems such as diabetes)?	Audit	2.0%
If you were to admit patients on PEG + ASC, how many nights before the procedure would you admit patients?	Audit	1
Given the clinical information you have been supplied about PEG + ASC, what percentage of in-patients would you expect to repeat due to poor visualization?	Audit	20%
Given the clinical information you have been supplied about PEG + ASC, what percentage of out-patients would you expect to repeat due to poor visualization?	Audit	3%
Cost of PEG + ASC?	MIMS	£9.87

Table 2.  Published efficacy results obtained in controlled clinical trials.

Study	Published efficacy results		Relative success ratio
	2 L PEG + ASC	Comparator	PEG + ASC: comparator
Bitoun et al.13	72.5%	64.9% (NaP)	1:0.89
Worthington et al.14	84.4%	72.8% (NaPic)	1:0.86

Table 3.  Overall cost differences (£) NaPic + MgCit (comparator) – PEG + ASC using the test data (500 colonoscopies per year).

Cost factor	Frail outpatients	Inpatients	Outpatients
First colonoscopy
Drug acquisition	−316.54	132.60*	443.94*
Bed days	127,914.50*	–	–
Procedure	−61,740.00	0.00	61,740.00*
Repeat colonoscopy
Drug acquisition	−158.27	66.30*	221.97*
Bed days	63,957.25*	–	–
Procedure	−30,870.00	0.00	30,870.00*
Overall	98,786.94*	198.90*	93,275.91*

*Indicates a budget impact benefit for PEG + ASC.

Figure 1.  Cost difference (in £) between comparator products and PEG + ASC in colonoscopy costs using test data.

Table 4.  Total and per patient cost calculations (£) using either NaPic + MgCit or PEG + ASC for the audit data collected from St. Georges Hospital, London.

	Drug acquisition costs		Procedure costs		Bed day costs		Full cost
	Total	Mean	Total	Mean	Total	Mean	Total	Mean
NaPic + MgCit	£8695.21	£3.62	£1,495,564.99	£623.15	£22,946.98	£9.56	£1,527,833.95	£636.60
PEG + Asc	£25,184.88	£10.49	£1,410,649.77	£587.77	£12,955.98	£5.40	£1,449,388.90	£603.91

Mean: Calculated values per patient (n = 2400).

Table 5.  Detailed total annual colonoscopy costs (£) from St. George’s Hospital, London.

Patient group	Cost factor	NaPic + MgCit	PEG + ASC
Frail out-patients	First acquisition drug cost (pa)	£210.60	£426.38
	Cost of bed-days (£227)	£14,709.60	£9806.40
	Cost of out-patient procedure (£504)	£32,659.20	£21,772.80
	Second acquisition drug cost	£117.94	£85.28
	Second cost of bed days	£8237.38	£1961.28
	Cost of second out-patient procedure (£504)	£18,289.15	£4354.56
	Total	£74,223.86	£38,406.70
Inpatients	First acquisition drug cost (pa)	£780.00	£2368.80
	Cost of procedure (£897)	£215,280.00	£215,280.00
	Repeat drug cost	£436.80	£473.76
	Cost of repeat procedure (£897)	£120,556.80	£43,056.00
	Total	£337,053.60	£261,178.56
Out-patients	First acquisition drug cost (pa)	£6809.40	£20,892.82
	Out-patient procedure (£504)	£1,055,980.80	£1,066,867.20
	Out-patient second acquisition drug cost	£340.47	£626.78
	Second cost out-patient procedure	£52,799.04	£32,006.02
	Total	£1,115,929.71	£1,120,392.82
Sub total cost (excluding lost revenue from Bowel Screening Programme)		£1,527,207.17	£1,419,978.08

Table 6.  Bowel cancer screening costs and revenues (UK).

Cost factor	NaPic + MgCit	PEG + ASC
Payment for the first screening series (£504)	£10,080.00	£10,080.00
Drug acquisition cost	−£65.00	−£197.40
Cost of frail outpatients admitted as inpatients (no repeat procedures assumed)	−£136.20	−£90.80
Cost of out-patient repeat procedures (£504)	−£504.00	−£302.40
Drug cost for outpatient repeat procedures	−£3.25	−£5.92
Total trust revenue from screening	£9371.55	£9483.48

Bitoun A, Ponchon T, Barthet M, et al. Results of a prospective randomised multicentre controlled trial comparing a new 2-L ascorbic acid plus polyethylene glycol solution vs. sodium phosphate solution in patients undergoing elective colonoscopy. Aliment Pharmacol Ther 2006;24:1631‐42

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Worthington J, Thyssen M, Chapman G, et al. A randomised controlled trial of a new 2 litre polyethylene glycol solution versus sodium picosulphate + magnesium citrate solution for bowel cleansing prior to colonoscopy. Curr Med Res Opin 2008;24:481‐8

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