The effects of inadequate preparation quality for colonoscopy

Eric Sherer and Michael CatlinAugust 20th, 2010

HSR&D Work-in-Progress

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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

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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

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Unanswered questions

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

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

• Adjust for individual colonoscopist• Want sensitivity NOT detection rates

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Adenoma detection rates

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

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Adenoma detection rates

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

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

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Adenoma detection rates

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

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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

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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

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Surveillance colonoscopy findings

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

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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]

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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

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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

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Methods

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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

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Functions

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Measuring patient outcomesQuality-Adjusted Life Years (QALYs)

40 yearsPerfect health (utility 1.0)40 QALYs

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Measuring patient outcomesQuality-Adjusted Life Years (QALYs)

40 yearsPerfect health (utility 1.0)40 QALYs

80 yearsPoor health (utility 0.5)40 QALYs

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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)

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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

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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

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Measuring clinic costs

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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.

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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

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Preliminary Results

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Clinic outcomes

E[colonoscopies / patient / life-year]

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

26.8% of surveillance colonoscopies due to inadequate prep

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Patient outcomes

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

E[CRC / patient]

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E[QALY / patient]

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E[colon costs / patient]

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E[CRC / patient]

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Secondary Outcome

Effect of prep quality intervention

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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

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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

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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

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