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Causal Analyses of Electronic Health Record Data for Assessing the Comparative Effectiveness of Treatment Regimens Romain Neugebauer, PhD Research Scientist II, Division of Research, Kaiser Permanente Northern California Romain Neugebauer


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Causal Analyses of Electronic Health Record Data for Assessing the Comparative Effectiveness of Treatment Regimens

Romain Neugebauer, PhD

Research Scientist II, Division of Research, Kaiser Permanente Northern California

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Romain Neugebauer

Disclosures

Rela latio ionship ip Company ny(ies es) Speakers Bureau Advisory Committee Board Membership Consultancy Review Panel PCORI Funding ME-1403-12506; ME-2018C1-10942 Honorarium Ownership Interests

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CER for Effective Management of Chronic Conditions

  • Long-term care requires frequent re-evaluation of treatment decisions
  • Chronic care model emphasizes personalization of care based on patient’s needs
  • Evidence most suited to inform real-world care involves the comparison of dynamic

treatment plans (as opposed to static treatment plans)

  • Example in diabetes care:
  • To avoid complications, clinicians aim to control blood glucose levels
  • Over time, glycemia tends to deteriorate prompting treatment intensification (TI)
  • TI timing is best informed by comparing dynamic treatment plans such as: “Intensify

therapy when the patient’s A1c reaches 7% versus 7.5%” instead of static plans “Intensify therapy 3 versus 6 months from now”

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Evaluation of Dynamic Treatment Plans

  • Ideally, using a trial design:
  • Randomize patients to one of several dynamic treatment plans
  • Contrast average outcomes between any two arms (e.g. survival curves)
  • Alternatively, by emulating trial inference using observational data:
  • Using a cohort study design and Causal Inference methods, such as:
  • Inverse probability weighting (IPW) estimation
  • Targeted minimum loss based estimation (TMLE)
  • Both IPW and TMLE methods can address time-dependent confounding
  • Originally, methods applied in studies with regular clinic visits (e.g., every 6 months)
  • More recently, methods applied to Electronic Health Record (EHR) data
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Evaluation of Dynamic Treatment Plans

  • IPW estimation is a propensity score (PS) method
  • Estimate the probability of exposure conditional on confounders over time
  • Use these estimated PS to construct weights
  • Compute weighted average of outcomes in each exposure group

 Correct inference relies on estimating the PS correctly

  • TMLE can provide more precise effect estimates and is doubly robust
  • Implemented by a sequence of (weighted) outcome regressions
  • PS are used to fit each regression
  • Compute average predicted values from the last regression in each exposure group

 Relies on either estimating the PS correctly or the outcome regressions

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Illustration with “Treatment Intensification” (TI) Study

  • Current recommendations specify a target A1c of <7% for most patients
  • Conflicting supporting evidence if patient on 2+ oral medications or basal insulin
  • To avoid or delay kidney disease, when should patient start an intensified therapy?
  • A retrospective cohort study using EHR of ≈ 51,000 adults from 7 US regions
  • Median follow-up of 2.5 years starting at first A1c≥7% between 2001 and 2009
  • Contrasted onset or progression of albuminuria between 4 dynamic treatment plans:

dθ: “Patient initiates TI the first time a newly observed A1c≥ θ% and continues the intensified therapy thereafter” with θ=7; 7.5; 8; 8.5%

  • Original results indicated strong evidence of risk reduction for TI at lower A1c
  • Frequency of A1c monitoring was ignored in the analyses
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Impact of A1c Monitoring on CER Evidence

  • In a trial to evaluate dynamic treatment plans, the

intervention protocol would specify an A1c monitoring schedule.

  • A patient randomized to treatment strategy d7.5 will

initiate TI when a physician first detects A1c ≥ 7.5%.

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Impact of A1c Monitoring on CER Evidence

  • In a trial to evaluate dynamic treatment plans, the

intervention protocol would specify an A1c monitoring schedule.

  • A patient randomized to treatment strategy d7.5 will

initiate TI when a physician first detects A1c ≥ 7.5%.

  • First time when A1c≥ 7.5%: just before quarter 9
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Impact of A1c Monitoring on CER Evidence

  • In a trial to evaluate dynamic treatment plans, the

intervention protocol would specify an A1c monitoring schedule.

  • A patient randomized to treatment strategy d7.5 will

initiate TI when a physician first detects A1c ≥ 7.5%.

  • First time when A1c≥ 7.5%: just before quarter 9
  • Detection time when A1c’s separated by
  • 1 quarter: quarter 9
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Impact of A1c Monitoring on CER Evidence

  • In a trial to evaluate dynamic treatment plans, the

intervention protocol would specify an A1c monitoring schedule.

  • A patient randomized to treatment strategy d7.5 will

initiate TI when a physician first detects A1c ≥ 7.5%.

  • First time when A1c≥ 7.5%: just before quarter 9
  • Detection time when A1c’s separated by
  • 1 quarter: quarter 9
  • 2 quarters: quarter 10
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Impact of A1c Monitoring on CER Evidence

  • In a trial to evaluate dynamic treatment plans, the

intervention protocol would specify an A1c monitoring schedule.

  • A patient randomized to treatment strategy d7.5 will

initiate TI when a physician first detects A1c ≥ 7.5%.

  • First time when A1c≥ 7.5%: just before quarter 9
  • Detection time when A1c’s separated by
  • 1 quarter: quarter 9
  • 2 quarters: quarter 10
  • 3 quarters: quarter 12
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Impact of A1c Monitoring on CER Evidence

  • In a trial to evaluate dynamic treatment plans, the

intervention protocol would specify an A1c monitoring schedule.

  • A patient randomized to treatment strategy d7.5 will initiate

TI when a physician first detects A1c ≥ 7.5%

  • First time when A1c≥ 7.5%: just before quarter 9
  • Detection time when A1c’s separated by
  • 1 quarter: quarter 9
  • 2 quarters: quarter 10
  • 3 quarters: quarter 12
  • Infrequent A1c testing leads to delayed TI for this patient.
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Impact of A1c Monitoring on CER Evidence

  • Trial inference about the comparative effectiveness of two identical dynamic plans is thus a function of

the A1c monitoring schedule chosen.

  • Similarly, CER evidence from observational data is also specific to the A1c monitoring frequency in the

cohort.

  • Methodological challenge and opportunity:
  • Generalizability problem: differences in monitoring protocols between two populations limits the

extrapolation of CER findings in one to the other

  • Generate new CER evidence to inform clinical monitoring decisions

We developed methods that can exploit the monitoring variability in EHR data to evaluate how monitoring and treatment decisions interact to impact health.

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Shortcomings of Existing Methods

  • Using EHR data from the TI study, we aimed to emulate a trial where participants would

be randomized to one of 6 arms:

dθ: “Patient initiates TI the first time a newly observed A1c≥ θ% and continues the intensified therapy thereafter” with θ=7.5; 8; 8.5% AND nX: A1c tests are separated by X quarters with X=1; 3.

  • Standard causal inference methods (IPW and TMLE) were used to evaluate

the effects of these 6 joint dynamic treatment and static monitoring interventions.

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Shortcomings of Existing Methods

  • When A1c’s are separated by one

quarter:

  • Effect of TI at lower A1c is mostly

protective

  • Wider confidence intervals

compared to original analyses without monitoring intervention

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Shortcomings of Existing Methods

  • When A1c’s are separated by 3

quarters:

  • Inconsistent and weak evidence
  • f a protective effect of TI at

lower A1c

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Shortcomings of Existing Methods

  • What explains the poor performance of standard IPW and TMLE?
  • Many patients follow the 3 dynamic treatment plans over two years.
  • Only patients with regular A1c tests contribute an outcome to standard analyses.
  • Very few patients exactly follow such rigid testing schedules over 2 years. Many

have more frequent or irregular A1c tests.

  • Example: ≈25,000 patients followed the dynamic treatment d8.5 through 1.5

years into the study but ≈1,000 did so while also having A1c tests collected every other quarter.

  • Small “sample sizes” in each exposure group explain the relative poor estimation

performance of standard analyses.

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Our Research to Address these Shortcomings

  • A five-pronged approach:
  • Develop theory to estimate the effect of a joint dynamic treatment and monitoring

intervention under a No Direct Effect assumption (NDE)

  • Empirically evaluate and illustrate resulting NDE-based IPW and TMLE estimators

with EHR data from TI study

  • Develop software to disseminate the novel estimation approaches
  • Validate theoretical findings and software implementation with simulated data
  • Seek guidance from stakeholder partners to improve practical relevance
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Results

  • Novel analytic tools can provide more precise estimates of the effects of

joint dynamic treatment and monitoring interventions.

  • Practical relevance:
  • Improve the generalizability of evidence about the comparative

effectiveness of dynamic treatment plans to population with different monitoring standards

  • Optimize clinical monitoring decisions
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Illustration with TI Study

  • No Direct Effect (NDE) assumption:
  • “A1c monitoring decisions can only impact outcomes and other covariates through

treatment decisions”

  • Potential violation: A1c testing increases subsequent health-seeking behaviors that

decrease the risk of albuminuria onset/progression.

  • If the assumption holds, we can estimate a joint dynamic treatment and static

monitoring intervention using data from patients whose A1c is monitored more frequently than what the monitoring intervention requires.

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Illustration with TI Study

  • When A1c’s are separated by one

quarter:

  • Without NDE (left):
  • Effect of TI at lower A1c is

mostly protective

  • Wide confidence intervals
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Illustration with TI Study

  • When A1c’s are separated by one

quarter:

  • Without NDE (left):
  • Effect of TI at lower A1c is

mostly protective

  • Wide confidence intervals
  • With NDE (right):
  • Effect of TI at lower A1c is

always protective

  • Tight confidence intervals
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Illustration with TI Study

  • When A1c’s are separated by three

quarters:

  • Without NDE (left):
  • Inconsistent evidence of TI

protection at lower A1c

  • Wide confidence intervals
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Illustration with TI Study

  • When A1c’s are separated by three

quarters:

  • Without NDE (left):
  • Inconsistent evidence of TI

protection at lower A1c

  • Wide confidence intervals
  • With NDE (right):
  • Effect of TI at lower A1c is

mostly protective

  • Tight confidence intervals
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Illustration with TI Study

  • If patients initiate TI at first A1c ≥

8%:

  • Without NDE (left):
  • Testing A1c more frequently

is protective

  • Wide confidence intervals
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Illustration with TI Study

  • If patients initiate TI at first A1c ≥

8%:

  • Without NDE (left):
  • Testing A1c more frequently

is protective

  • Wide confidence intervals
  • With NDE (right):
  • Testing A1c more frequently

is protective

  • Tight confidence intervals
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Limitations

  • Analytic methods developed rely on the strong assumption of “no

unmeasured confounding” (NUC) for both the effect of treatment decisions and the effect of monitoring decisions on outcome.

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Acknowledgments

Investigators Alyce Adams • Richard Grant • Julie Schmittdiel • Oleg Sofrygin • Mark van der Laan TI Study Investigators Connie Trinacty • Kristi Reynolds • Denise Boudreau • Marsha Raebel • Gregory Nichols • Patrick O’Connor • Joe Selby Patient, Provider, & Healthcare System Stakeholders Arjun Varma • Patrick O’Connor • Edward Yu • Richard Brand • Juanita Thomas • Marc Jaffe • Michael Chae Visiting Fellow Noémi Kreif

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Learn More

  • Manuscripts
  • Neugebauer, R, Schmittdiel, JA, Adams, AS, Grant, RW, van der Laan, MJ (2017). Identification of the

joint effect of a dynamic treatment intervention and a stochastic monitoring intervention under the no direct effect assumption. J Causal Inference, 5, 1.

  • Kreif, N, Sofrygin, O, Schmittdiel, JA, Adams, AS, Grant, RW, Zhu, Z, van der Laan, MJ, Neugebauer, R

(2018). Evaluation of adaptive treatment strategies in an observational study where time-varying covariates are not monitored systematically. In review. https://arxiv.org/abs/1806.11153

  • Software
  • Sofrygin O, van der Laan MJ, Neugebauer R (2016). stremr R package.

https://github.com/os9ofr/stremr.