Causal Effect of Managed Care on Health Care Quality: Evidence from Cancer Screening Guideline Disco

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Causal Effect of Managed Care on Health Care
Quality Evidence from Cancer Screening
Guideline DiscontinuitiesSrikanth
KadiyalaGrant MillerHarvard
UniversityFunding Sloan Foundation, NIH
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• Dr. Sandy MacColl one of the founders of GHC
  wrote that he and his colleagues sought a system
  of family caredirected towards a goal of good
  care, health maintenance and preventive services
• Crowley,To serve the greatest number
• A History of the GHC of Puget Sound

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Managed Care

• Held Great Promise for Quality Improvements
• Lower Cost
• Appropriate Use of Medical Care
• Conventional View is that it has Failed
• We Contend Jury is Still Out

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Previous Research

• Randomized Control Trial
• Rand HI experiment (late 1970s)
• Cross-Sectional Studies
• Selection problem since assignment to insurance
  type is NOT random
• Control for observables
• Findings Equivocal

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New Empirical Strategy

• Discontinuity design using age-specific
  preventive service guidelines
• Within plan comparisons of preventive service use
  across guideline thresholds difference out
  selection effects
• Guidelines are bright lines-No discrete
  increase in cancer risk at these ages

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Cancer Screenings Recommendations

• U.S Preventive Task Force (USPSTF) and American
  Cancer Society (ACS)
• Colorectal Cancer
• USPSTF ACS Both recommend screening for
  individuals age 40
• No recommendation on screening technology
• Breast Cancer
• ACS-Recommended mammography for women ages 40
  since early 1980s
• USPSTF-Recently switched to 40, previously 50
• Thus we look for changes over both the 40 and 50
  year thresholds
• Prostate Cancer
• USPSTF-Does not recommend PSA
• ACS-Physicians should offer PSA
• Screening is Recommended for these diseases ONLY
  for asymptomatic people above a certain age
• IOM/ Quality Chasm report Cancer Screenings
  UNDERUSED

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Natural Experiment Framework
Managed Care
FFS
Pre- guideline
Post Guideline
Pre- guideline
Post Guideline
49
49
50
50
Difference-In-Difference-In-Difference
(D-B)-(C-A) (H-F)-(G-E)
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Regression Discontinuity
Managed Care
FFS
Post Guideline
Post Guideline
49
49
50
50

• Diff.-In-Diff.(D-B) (H-F)

-This assumes that (G-E)-(C-A) is zero, which
is a plausible assumption
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Data

• National Health Interview Survey(NHIS)
• National Sample of Individuals
• Breast Cancer (N6807,Years 1998-2000)
• Colorectal Cancer (N3426,Year 2000)
• Prostate Cancer(N1543,Year 2000)
• Insurance Plan Types
• Group/Staff Models, IPA, POS, PPO,
  Fee-For-Service(FFS)
• Rich Set of Covariates
• Income, Education, Race, Region, Marital Status
• Also MarketScan Data 1997-2001(these results not
  reported)

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Colorectal Cancer Any Screening in Last Year
by Plan and Age
NHIS Data-Year 2000
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Breast Cancer Mammogram Use in Last Year by
Plan and Age
NHIS Data 1998-2000
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Breast Cancer Mammogram Use in Last Year by
Plan and Age
NHIS Data 1998-2000
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Prostate CancerPSA Test Use in Last Yearby Plan
and Age
NHIS DATA Year 2000
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Regression Discontinuity Estimate using
Colorectal Cancer Means by Plan and Age Group
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Regression Estimates of Screening Use
Standard Errors in parantheses. Bold indicates
point estimate is significant at the 5 level.
Italics means significant at the 10
level. Regression models adjust for age,sex,race,
education, income,marital status, region and time
where appropriate.
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Results from Cross-Section Regressions
Standard Errors in parantheses. Bold indicates
point estimate is significant at the 5 level.
Regression models adjust for age,sex,race,
education, income,marital status, region and time
where appropriate.
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Interpretation of Results

• Change in Use across Age thresholds generally
  larger in Managed Care Plans
• Large statistically significant differences for
  Colorectal and Breast Cancer screenings
• No Statistically Significant differences for
  Prostate Cancer Screening
• Strongest Results for the Group/Staff Managed
  Care Models

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Supply or Demand

• Survey data indicates individuals dont know the
  right age cutoffs
• We know whether people were offered screening
  services in the 2000 NHIS data
• Using the same framework as above we find large
  statistically significant changes in Offer rates
  across the relevant age thresholds
• This indicates that supply side responses drive
  changes in use over the age thresholds.

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Future Work

• How does Managed Care do it?
• Plan Characteristics
• Health Effects
• Other treatments with Age Thresholds
• Ex. Cholesterol Screening