The effects of inadequate preparation quality for colonoscopy

The effects of inadequate preparation quality for colonoscopy

Eric Sherer and Michael CatlinAugust 20th, 2010

HSR&D Work-in-Progress

1

Outline

• Background– Lengthy– Adenoma detection rates– Appendix… or stand alone???

• Outcomes• Methods– Random questions

• Compliance• Costs• Mortality

• Preliminary results

ORANGE TEXT => INPUT FROM AUDIENCE2

Background

3

Detection rates - Literature• Harewood et al. 2003– 93,004 colonoscopies– Adequate vs. Inadequate– POLYPS– <10 MM

• Froechlich et al. 2005– 5,832 colonoscopies– Low vs. Intermediate quality– Low vs. High quality– POLYPS– <10 MM

4

Unanswered questions

• What about adenomas?• Diminutive (<=5mm) vs. small (<10mm)

adenomas?– “cannot exclude adenomas <=5mm”

• Adjust for individual colonoscopist• Want sensitivity NOT detection rates

5

Adenoma detection rates

Padequate vs. fair = 0.17Padequate vs. poor < 0.01

6

Adenoma detection rates

Padequate vs. fair = 0.62 Padequate vs. poor = 0.80

Padequate vs. fair = 0.28 Padequate vs. poor < 0.01

7

Adenoma detection rates

Padequate vs. fair = 0.25 Padequate vs. poor < 0.01

8

Adenoma detection rates• Medium adenomas (6-9mm)– Adequate vs. poor prep qualities• 22% relative difference; 3.2% absolute difference

– Adequate vs. fair prep qualities• 13% relative difference; 1.9% absolute difference

Padequate vs. fair = 0.16 Padequate vs. poor = 0.21

9

Adenoma detection rates• Medium adenomas (6-9mm)– Adequate vs. poor prep qualities• 22% relative difference; 3.2% absolute difference

– Adequate vs. fair prep qualities• 13% relative difference; 1.9% absolute difference

10

Surveillance colonoscopy findings

11

Outcomes• Effects of inadequate preparation quality– Missed adenomas => Δcancer

12

Recommendations after 1st colonoscopy

• 2003-2010 colonoscopy prep qualities– 1,675 (64.1%) adequate– 750 (28.7%) fair– 187 (7.1%) poor

ADEQUATE PREP QUALITY

FAIR PREP QUALITY POOR PREP QUALITY

ADEQUATE v.FAIR

FAIR v.POOR

Colonoscopy finding Mean recommended follow-up (s.d.)

Mean recommended follow-up (s.d.)

Mean recommended follow-up (s.d.)

Δ Follow-up[95% CI]

Δ Follow-up[95% CI]

No adenomas (10yrs) 8.01yrs (2.69)n = 754

5.11yrs (2.65)n = 316

1.63yrs (2.07)n = 102

2.90yrs[2.72, 3.08]

3.48yrs[3.23, 3.73]

1-2 non-advanced adenomas only (5-10yrs)

4.66yrs (1.00)n = 324

3.43yrs (1.48)n = 148

1.81yrs (1.50)n = 35

1.23yrs[1.10, 1.36]

1.62yrs[1.34, 1.90]

3+ non-advanced adenomas only (3yrs)

3.24yrs (1.03)n = 149

2.32yrs (1.21)n = 97

1.19yrs (0.53)n = 8

0.92yrs[0.77, 1.07]

1.13yrs[0.91, 1.35]

any advanced adenoma 2.05yrs (1.36)n = 135

1.48yrs (1.32)n = 72

1.19yrs (1.49)n = 12

0.57yrs[0.38, 0.76]

0.29yrs[-0.17, 0.75]

13

Effect of inadequate preparation

• Rex et al. 2002– 400 patients• 200 public hospital• 200 private hospital

– Authors assumed…• Perfect inadequacy• Perfect compliance• Procedure invariance

Number of projected colonoscopiesYear Ideal

PreparationPrivate

HospitalPublic

Hospital0 – 1 200 202 2131 – 2 0 25 402 – 3 0 0 03 – 4 20 17.5 164 – 5 0 4.7 7.25 – 6 40 35 326 – 7 0 9.4 14.4Total 260 293.6 322.6

Increase 12.9% 24.1%

Projected total costsCost $213,841 $239,068Cost $220,260 $267,566

Increase 11.8% 21.5%14

Outcomes• Effects of inadequate preparation quality– Missed adenomas => Δcancer– Earlier recalls => Δnumber of tests

15

Outcomes

• Primary– Patient• Δ E[Quality adjusted life-year (QALY)]• Δ E[colon costs]• Δ lifetime CRC risk

– Clinic• Δ E[colonoscopies / patient / life-year]

– (How many more colonoscopies are done per patient each year)

• Secondary– Prep quality intervention

16

Methods

17

Calculations

Monte Carlo trials• Select patient

– Colon disease free & 50<=age<=80

• r1 Select random prep quality– f (gender, BMI, prev prep quality)

• r2 Random colonoscopy findings– History dependent

• r3 Select compliance– 40% - 80% reported in literature– Independent events vs. All-or-nothing

• r4 Determine follow-up interval– Expected vs. distributed behavior

• r5 Age > 80? Age > 100?

Implementation• All adequate prep scenario• “Normal” prep scenario

• Range of compliances– Independent & greedy assumptions

• To-do: Sensitivity analysis– Costs

18

Functions

19

Measuring patient outcomesQuality-Adjusted Life Years (QALYs)

40 yearsPerfect health (utility 1.0)40 QALYs

20

Measuring patient outcomesQuality-Adjusted Life Years (QALYs)

40 yearsPerfect health (utility 1.0)40 QALYs

80 yearsPoor health (utility 0.5)40 QALYs

21

Measuring patient outcomesQuality-Adjusted Life Years (QALYs)

40 yearsPerfect health (utility 1.0)40 QALYs

80 yearsPoor health (utility 0.5)40 QALYs

non-cancerous 0.91

local CRC 0.74

regional CRC 0.50

metastatic CRC 0.25

Utility of model states (Ness et al. 2000)

22

Measuring clinic costs

• CRC treatment• Initial costs• Continuing costs

(Ness et al. 2000)

• Colonoscopies• Colonoscopy• Polypectomy• Pathology

• Complications• Perforation

Local Regional Metastatic

Initial $16,051 / yr $18,457 / yr $21,093 / yr

Continuing $425 / yr $1,944 / yr $21,209 / yr

23

Measuring clinic costs

• CRC treatment• Initial costs• Continuing costs

(Ness et al. 2000)• Terminal care costs not included

• Colonoscopies• Colonoscopy• Polypectomy• Pathology

• Complications• Perforation

Local Regional Metastatic

Initial $16,051 / yr $18,457 / yr $21,093 / yr

Continuing $425 / yr $1,944 / yr $21,209 / yr

24

Measuring clinic costs

25

Measuring clinic costs

• CRC treatment• Initial costs• Continuing costs

• Colonoscopies• Colonoscopy• Polypectomy• Pathology

• Complications• Perforation (0.2% incidence, 0.01% mortality)

(Tafazzoli et al. 2009) 26

Measuring mortality

Discount each event by the probability of prior mortality.

27

Measuring mortality

Discount each event by the probability of prior mortality.

Patient viability with age

Patient age

Ai = age at first colonoscopy

Af = current age

28

Preliminary Results

29

Clinic outcomes

E[colonoscopies / patient / life-year]

30

E[N] of surveillance colonoscopies:Independent event assumption w/ ghosts

26.8% of surveillance colonoscopies due to inadequate prep

31

Patient outcomes

E[QALY / patient]E[colon costs / patient]

E[CRC / patient]

32

E[QALY / patient]

33

E[colon costs / patient]

34

E[CRC / patient]

35

Secondary Outcome

Effect of prep quality intervention

36

E[N] surveillance colonoscopies100% compliance

Intervention Lifetime E[N] surveillance colonoscopies

% due to prep quality

No intervention 3.57 26.8%

10% bumped 1 level 3.50

20% bumped 1 level 3.44

30% bumped 1 level 3.37

37

Big Picture• Overall project Objective:– “Best” time for a patient to receive colon tests

• Tools needed– Longitudinal predictions

• Test parameters– Cost-utility – Decision analysis 38

Adequate

First-time (Roudebush data) 2.07%

Following (model)

First-time colonoscopy 0.68%

Second-time colonoscopy 0.16%

Third-time colonoscopy 0.02%

Thank you

39

40

41

42

Limitations

Discussed in Rex et al. 2002• Correlation in prep qualities• Additional surveillance

colonoscopies

Additional• Likelihood of CRC• Intermediate preps, detection & recs• Longitudinal adenoma prevalence• Study interval bias

43