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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