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Abstracts from the 28th Annual Meeting of the
Society for Medical Decision Making (October 15-18, 2006)
- ARE PATIENT CHARACTERISTICS ASSOCIATED
WITH THEIR UNDERSTANDING OF PHYSICIAN ADVICE TO CURTAIL ALCOHOL USE?
- IMPACT OF COGNITIVE DEFICITS ON HEALTH
STATE VALUATION BY DEMENTIA PATIENTS
- PERFORMANCE OF SIMPLE VS. COMPLEX MODELS
FOR RISK-ADJUSTING PRIMARY CESAREAN DELIVERY RATES
- COMPARISON OF NATIONAL VS.REGIONAL AND
STATE LEVEL MODELS FOR RISK ADJUSTING PRIMARY CESAREAN DELIVERY RATES
- USE OF COMPLIMENTARY AND ALTERNATIVE MEDICINE
(CAM) FOR HEPATITIS C (HCV): PATIENTS' INFORMATION SHARING AND DECISION
MAKING ON THE INTERNET
- USING THE WAITING LIST INFORMATION TO OPTIMIZE
THE TIMING OF LIVER TRANSPLANTATION
- IS QUITTING DRINKING THE SAME AS ABSTINENCE?
EVIDENCE FROM A MIXED METHODS STUDY OF NON-DEPENDENT DRINKERS WITH HEPATITIS
C
- VALIDATION OF AN ASTHMA COMPUTERIZED DECISION
SUPPORT SYSTEM
- ASSESSING DYNAMIC MAMMOGRAPHY SCHEDULES:
A MATHEMATICAL MODELING BASED APPROACH
- COST-EFFECTIVENESS OF A ROTAVIRUS VACCINATION
PROGRAM IN INDIA
- EMR-FACILITATED DESIGN OF A CLUSTER-RANDOMIZED
TRIAL OF CLINICAL DECISION SUPPORT FOR DIABETES
Noah J. Webster, MA, Case Western Reserve University, Cleveland,
OH, Adam T. Perzynski, MA, Case Western Reserve University, Cleveland, OH,
Richard A. McCormick, PhD, Case Western Reserve University, Cleveland, OH,
Carol E. Blixen, PhD, Cleveland Clinic, Cleveland, OH, Stephanie W. Kanuch,
MEd, Case Western Reserve University/MetroHealth Medical Center, Cleveland,
OH, Eleanor P. Stoller, Wake Forest University, Winston-Salem, NC, and Neal
V. Dawson, MD, Case Western Reserve University/MetroHealth Medical Center,
Cleveland, OH.
Purpose: Past studies have found that
even at relatively low levels of intake, long-term use of alcohol can
adversely influence the prognosis for patients chronically infected with
Hepatitis C Virus (HCV). Continued alcohol use with HCV can lead to cirrhosis
and/or hepatic cancer, suggesting abstinence is best. Research has demonstrated
differences among physicians in what they tell patients about whether
various levels of alcohol consumption are safe. Gastroenterology (GI)
specialists almost universally advise HCV patients to never drink alcohol.
Despite a strong message from a GI specialist, some patients may process
health information differently based upon socio-demographic, cultural,
or personality characteristics. The purpose of this study is to examine
the frequency and characteristics associated with HCV patients who have
seen a GI specialist and who report their physician told them to never
drink.
Methods: HCV patients (N=349) who saw a GI specialist at an urban
Midwest teaching hospital were interviewed over the telephone. Patients
answered questions about their alcohol use, healthcare behaviors, psychological
traits, and coping styles. All patients were asked if they had been
told by a physician to never drink. Standard clinical practice at this
hospital is for all GI specialists to advise HCV patients to never drink
alcohol. We assume that all patients in the sample were told by a physician
to never drink. The dependent variable for the logistic regression was
Did a physician tell you to never drink alcohol? (yes/no).
Results: Sixty-eight percent (95% CI, 63-73) of the patients reported
a physician told them to never drink. Males (OR=.46, p=.01) and patients
with lower incomes (OR=.19, p=.01) were more likely to report being
told to never drink. Likewise, individuals scoring higher on a neuroticism
scale (OR=1.11, p=.04) and those who take a planful approach to coping
(OR=1.14, p=.02) were more likely to report being told to never drink.
Future analyses will examine the conditional effects of gender and race.
Conclusions: Socio-demographic and psychological differences are associated
with patients' reports about abstaining from alcohol. Physicians need
to be sensitive to these differences to equip their patients with the
knowledge needed to make the best decision about their alcohol use.
To achieve this goal, we will need to examine various ways to present
the same message to different types of patients.
Susie A. Sami, MA1, Neal Dawson, MD2, Marian
B. Patterson, PhD1, Mendel E. Singer, PhD3, Kathleen
A. Smyth, PhD1, Iahn Gonsenhauser, MBA1, and Peter
J. Whitehouse, MD, PhD1. (1) Case Western Reserve University,
Cleveland, OH, (2) Case Western Reserve University - MetroHealth Medical
Center, Cleveland, OH, (3) Case Western Reserve University School of Medicine,
Cleveland, OH
Purpose: The purpose of this study was to assess associations between
cognitive deficits and ability of patients with dementia (PWD) to state
their health care preferences. Method: In this cross-sectional study,
visual analog scale, time trade-off, and standard gamble health state
valuation (HSV) techniques were used. Sixty PWD were asked to provide
HSV for 2 practice states (dependence on glasses; blindness), their
current health, and 3 hypothetical disease states (mild memory problems;
mild to moderate dementia; severe dementia). The outcome variable, ability
to perform HSV, was scored dichotomously. Patients received scores of
1 if they completed and provided logically consistent responses to both
practice states and at least one additional HSV using any 1 of the 3
techniques. Those not able to perform at this level received scores
of 0. Patients completed a neuropsychological test battery to assess
4 cognitive domains: executive function, language, attention and concentration,
and verbal memory. Logistic regression was used to examine associations
between cognitive domain scores and HSV performance. Results: The sample
was 55% male and had a mean age of 74.9 (s.d.=9.4). Most participants
(87%) had at least a high school education. Participants had mild to
moderate dementia (Mini Mental State Exam mean = 22.8, s.d. =5.5). Cognitive
subscale items were standardized before computing the domain scores.
Means and standard deviations were as follows: executive function (-0.04,
1.38), language (0.12, 2.77), attention and concentration (0.03, 2.21)
and verbal memory (0.13, 2.47). Higher language and verbal memory scores
increased the odds of completing the HSV (OR=4.24, p=0.002; OR =1.79,
p=0.04, respectively). There was a trend for higher scores on attention
and concentration to be associated with a decreased odds of completing
the HSV tasks (OR=0.44, p=0.059). The association between executive
function scores and completion of the HSV tasks was not significant.
The model c statistic was 0.90 (p<0.001). Conclusion: Dementia patients
with relatively preserved language and verbal memory abilities are better
able to complete the complex tasks involved in HSV. Clinically, these
patients may still be able to state their health care preferences. The
findings regarding attention and concentration are puzzling. Further
study of the relationship between these cognitive functions and ability
to perform HSV are needed.
Jennifer L. Bailit, MD, MPH, Case Western Reserve University - MetroHealth
Medical Center, Cleveland, OH and Thomas Love, PhD, Case Western Reserve
University - MetroHealth Medical Center, Cleveland, OH.
Purpose: To assess whether the addition of splines
and interaction terms improve the performance of a validated risk-adjustment
model for primary cesarean rates.
Methods: We built several logistic regression models for primary
cesarean delivery using maternal risk factors. We utilized California
birth certificate data for 2003 linked to hospital discharge data
for mothers and babies. Model predictors included: maternal age,
race, and medical conditions, gestational age, multiple births, insurance,
nulliparity, complications of pregnancy, and the trimester in which
prenatal care began. Our initial model (validated for other states)
uses linear functions of main effects for all independent variables.
Here, we augmented this using subgrouping,
smoothing and cubic spline function techniques
to capture potential non-linearity and interaction effects. We report
bootstrap estimates of model calibration and discrimination through
C statistics (area under the receiver operating characteristic curve),
Brier scores, and calibration plots.
Results: After cleaning, our models describe 382,566 births. We report
on three logistic regressions motivated by exploratory analyses.
Model A incorporates key predictors as linear main effects (C statistic
.765). Model B uses restricted cubic splines
to capture potential non-linearity in maternal age (C statistic .766).
Model C adds interactions of maternal age with other key predictors
(C statistic .766). Brier score was 0.117 for each.

Conclusions: Despite significant differences in likelihood ratio testing
(p<.0001), all three models show comparable discrimination and calibration,
suggesting no real performance advantage for the more complex models.
In the interests of parsimony and improving clinical understanding, we
plan to focus future work on model A, which mirrors
our previously validated approaches.

Jennifer L. Bailit, MD, MPH, Case Western Reserve University - MetroHealth
Medical Center, Cleveland, OH and Neal Dawson, MD, Case Western Reserve
University - MetroHealth Medical Center, Cleveland, OH.
Purpose: Obstetrical quality is measured at the national level rather
than the local level. Our study sought to compare the predicative
ability of primary cesarean delivery models at the national, regional,
and state levels.
Methods: National birth certificate data for 2003 were used to build
a standard national risk-adjustment model for primary cesarean delivery.
Variables in the model included: maternal age, gestational age, multiple
births, nulliparity, complications of pregnancy, maternal medical
conditions, and the trimester in which prenatal care began. The same
variables were then used to run models and generate beta weights at
the regional and state levels. All models were boot strapped and
c statistics and confidence intervals were determined.
Results: There were 3,475,663 births in the data set after cleaning.
C statistic were similar for all models and
95% confidence intervals show significant overlap at the national,
regional, and state levels.
Figure 1. C
statistics and 95% confidence intervals for primary cesarean risk-adjustment
models for the US,
regional and selected states.
Conclusions: Within the United
States, region specific models do not outperform
a national model for risk-adjusting primary cesarean delivery rates. These
data appear to suggest that regional models are not necessary and that
a national risk-adjustment model can safely be used by quality assessment
organizations.

Carol E. Blixen, PhD1, Noah J. Webster, MA2,
Adam T. Perzynski, MA2, Eleanor P. Stoller, PhD3,
Joshua J. Terchek, BA2, Stephanie W. Kanuch, MEd4,
Andrew J. Hund, MA2, Richard A. McCormick, PhD2, and
Neal V. Dawson, MD4. (1) Cleveland Clinic, Cleveland, OH, (2)
Case Western Reserve University, Cleveland, OH, (3) Wake Forest University,
Winston-Salem, NC, (4) Case Western Reserve University/MetroHealth Medical
Center, Cleveland, OH
Purpose: Patients often consult informal
sources, including the internet, to aid them with treatment decisions
about their disease. In light of the growing use of complimentary and
alternative medicine practices (CAM) such as the use of herbs, supplements,
acupuncture, etc, among patients with hepatitis C (HCV), we explored the
topics surrounding patients' decisions to use CAM therapies for this disease
as discussed on the internet.
Methods: Two sources of cross-sectional textual data were collected
from the internet and analyzed for this study: (1) 307 electronic illness
narratives posted on the topic of HCV from eight English language websites;
and (2) 264 threaded discussions that included 534 discussants from
four internet sites on the topic of HCV. The data were analyzed by first
importing the text files into NVIVO (qualitative data management software)
and coding any reference to CAM. Next, using the procedure of open-coding,
the researchers independently reviewed the CAM text and generated a
list of descriptive codes (topics). The researchers then met to compare
lists and agree on a final version of the codes and their sub-categories.
Results: Nine descriptive codes, related to information sharing and
decision making about the use of CAM for HCV, emerged from analysis
of the qualitative data: 1) Reasons for Using CAM (liver health, dissatisfaction
with traditional treatment, treatment of symptoms and side effects);
2) Research and Education on CAM (internet, books, seeking advice from
others); 3) Types of CAM Used (herbs, supplements, behavioral, CAM provider
based therapies); 4) Types of CAM Providers Seen (homeopaths, naturopaths,
herbalists, acupuncturists, etc); 5) Therapeutic Regimens of CAM (combinations,
dosages, frequency); 6) Perceived Results of CAM (positive, negative);
7) Cost Issues of CAM (price, insurance); 8) Re-evaluation of CAM Use
(continue, discontinue); and 9) Sharing Experiences/Giving Advice about
CAM Use.
Conclusions: The internet is a venue where a large amount of information
about CAM is shared and a powerful tool for aiding patients in the medical
decision making process. In order to assist patients with HCV in choosing
therapies that are efficacious and safe, healthcare providers need to
be aware of the wide range of topics that impact on the decision to
use CAM therapies, and be able to discuss them with their patients.

Burhaneddin Sandikci, MS, University of Pittsburgh, Pittsburgh, PA,
Oguzhan Alagoz, PhD, University of Wisconsin, Madison, WI, Lisa Maillart,
PhD, Case Western Reserve University, Cleveland, OH, Andrew Schaefer, PhD,
University of Pittsburgh, Pittsburgh, PA, and Mark S. Roberts, MD, MPP,
University of Pittsburgh, Pittsburgh, PA.
Purpose. Currently, patients waiting
for a cadaveric liver have little information regarding their position
on the waiting list. This study aims to evaluate whether knowledge of
specific location on the waiting list changes the optimal accept/reject
decision for a given donor organ and shows the value of making the waiting
list information transparent. Methods. We model the problem of accepting
or rejecting a liver offer as a Markov decision process (MDP). The state
of the system is composed of the triplets (h,k,l), where ‘h' represents
the health status of the patient, ‘k' is the rank of the patient in the
waiting list for the current liver offer, and ‘l' is the quality of the
liver as determined by the characteristics of the donor such as age, gender,
race, etc. The transition probabilities of the system are estimated using
the natural history of liver disease as well as a previously validated
national liver allocation simulation model. Optimal accept/reject decisions
are found using the policy iteration algorithm. Results. The optimal accept/reject
decisions take a ‘control-limit' form as shown in the figure. The horizontal
axis shows the health of the patient as measured by MELD score. (Higher
MELD scores represent sicker patients). The possible ranks of the patient
are displayed on the vertical axis, where a zero rank is interpreted as
the patient being off of the waiting list at the current stage. Each line
represents a different organ quality where organ quality decreases from
1 to 14. For each organ quality, the area is split into two regions by
the threshold line, where the optimal action is to ‘reject' the offer
below the line (inclusive) and to ‘accept' the offer above the line. For
the first 5 organ qualities (i.e., the top five quality organs) the optimal
action is always to ‘accept' regardless of the health/rank combination
(i.e., the lines associated for these organs coincide with the horizontal
axis). If the organ quality further decreases, the rank threshold increases.
In general, the reject region becomes larger as the quality of the organ
decreases. Conclusion. The probabilistic model used shows that the optimal
decision changes significantly if the waiting list information is known
to the decision maker (patient/surgeon).


Adam Perzynski, MA1, Stephanie Kanuch, MEd2,
Noah Webster, MS1, Richard McCormick, PhD1, Eleanor
P. Stoller, PhD1, Carol E. Blixen, PhD3, Joshua Terchek,
BA1, and Neal Dawson, MD4. (1) Case Western Reserve
University, Cleveland, OH, (2) Metrohealth Medical Center, Cleveland, OH,
(3) Cleveland Clinic, Cleveland, OH, (4) Case Western Reserve University
- MetroHealth Medical Center, Cleveland, OH
Purpose: Physicians caring for patients
with Chronic Hepatitis C Virus (HCV) need to ascertain how much their
patients are drinking. Patients with HCV may improve their prognosis by
reducing or abstaining from alcohol use, even if they are not candidates
for HCV drug treatments. A two phase investigation was employed to determine
whether patient reports of quitting drinking are the same as total abstinence.
Methods: To be eligible for the study, patients had to be HCV positive,
non-dependent drinkers. In Phase I, 42 subjects were recruited using
a sampling grid to ensure a balance of race (White, African American,
and Hispanic) and gender. Eligible patients who consented in Phase I
were interviewed using a semi-structured format. Qualitative software
was used to organize and analyze interview transcripts. In Phase II,
398 patients completed a telephone survey. Alcohol use was assessed
using the Alcohol Use Disorders Identification Test (AUDIT) and the
question “Have you quit drinking?” Both samples were drawn from the
population of HCV patients at an urban teaching hospital.
Results: In Phase I, 20 patients said that they quit drinking or were
a non-drinker. 12 of these 20 described in their interviews that they
had continued to consume some alcohol. In Phase II, of those who reported
quitting drinking 5% (95% CI, 2-7) had an AUDIT score greater than zero.
A logistic regression of 64 covariates was used to compute the propensity
score for the 398 Phase II subjects. The propensity score was used to
create ten subclasses of patients matched by their propensity to have
quit drinking. Mean scores on the AUDIT were compared within each of
the ten subclasses. Patients who reported they quit drinking (N=272)
had a weighted mean AUDIT score of .11 (95% CI, .05-.17) while patients
who did not quit drinking (N=126) had a weighted mean AUDIT score of
2.97 (95% CI, 2.69-3.25).
Conclusions: Nearly all patients who reported having quit drinking
abstained from alcohol completely in the past year. However for some
HCV patients, quitting may imply a reduced pattern of drinking behavior
rather than total abstinence. Doctors should discuss alcohol use with
their patients using unambiguous questions that address the quantity
and frequency of alcohol consumption, as well as the date of the last
drink.

Thomas Stern, MD, MS, Carolinas Medical Center, Charlotte, NC, Asha
Garg, MD, MPH, Case Western Reserve University School of Medicine, Cleveland,
OH, Neal V. Dawson, MD, Metrohealth Medical Center, Cleveland, OH, Nancy
Messina, RRT, Division of Pulmonary, Critical care, and Sleep Medicine,
MetroHealth Medical Center, Cleveland, OH, and E. Regis McFadden, MD, Center
for Academic Clinical Research, General Clinical Research Center, Case Western
Reserve University, Cleveland, OH.
Purpose: Primary care practitioners
have had difficulty implementing published guidelines for the diagnosis
and management of asthma. Computerized decision support systems are tools
that have been proven to improve compliance with published guidelines.
This study's objective is to assess the accuracy of a computerized asthma
decision support system in recognizing severe asthma using expert asthma
clinicians as the reference standard.
Methods: This study is an accuracy assessment of 69 consecutive patients
seen in an urban asthma subspecialty clinic between August 1 and November
30, 2004. Patients' asthma was classified as “severe” or “mild” both
by the decision support system and expert asthma clinicians who were
blinded to the assessment of the decision support system. Accuracy was
quantified using percent accuracy, sensitivity, specificity, positive
predictive value, negative predictive value, and positive and negative
likelihood ratios using the expert asthma clinicians as the reference
standard.
Results: The decision support system had a 91% accuracy of recognizing
severe asthma defined by expert asthma clinicians. The sensitivity of
the decision support system for severe asthma was 96%, the specificity
was 73%, the positive predictive value was 93%, the negative predictive
value was 85%, the positive likelihood ratio was 3.6 (95% CI: 1.6, 8.4),
and the negative likelihood ratio was 0.05 (95% CI: 0.012, 0.21).
Conclusions: The asthma decision support system was able to discern
“mild” from “severe” asthma in a similar fashion to expert asthma clinicians.
The effect of the decision support system on patient outcomes should
be assessed.

Lisa Maillart, PhD, Case Western Reserve University, Cleveland, OH,
Julie S. Ivy, PhD, University of Michigan, Ann Arbor, MI, Scott Ransom,
DO, MBA, MPH, University of Michigan, Ann Arbor, MI, and Kathleen M. Diehl,
M.D., FACS, University of Michigan, Ann Arbor, MI.
Purpose: Although the potential for
mammography screening to reduce breast cancer mortality risk is generally
accepted for older women, some authors argue the benefits for younger
women are less certain, because disease incidence and screening test accuracy
are lower in younger women. Alternatively, the American Cancer Society
Guidelines for Breast Cancer Screening state annual screening is more
important for younger women since the disease is more aggressive in younger
women. The primary objective of this research is to resolve these opposing
viewpoints on selecting mammogram screening intervals for both life phases.
Method(s): We formulate a partially observed Markov decision process
(POMDP) model exploring the relationship between mammography screening
frequency and lifetime mortality risk. This approach incorporates the
unobservable disease progression, the possibility of false results,
and the possibility of unsuccessful treatment upon detection. We use
this model to evaluate different screening policies and to construct
tradeoff curves that plot “policy effort” versus mortality risk.
Results: We conduct a numerical study for a 25 year-old patient without
cancer. By our analysis, we determine which policies are dominant, draw
conclusions regarding the interaction between problem parameters (disease
incidence, disease aggression, comorbidities, screening efficacy, screening
start age, switch age, and stop age) and answer open questions concerning
the value of dynamic (two-phase), versus routine (single-phase), screening
policies.
Conclusions: A patient can achieve an intermediate breast cancer mortality
risk using a dynamic policy rather than a “routine” policy. Our analysis
provides the following preliminary insights: (i) annual screening beginning
at 40 is efficient (ii) most switch ages for efficient two-phase policies
are in the 50s; (iii) the most common screening start ages are 30 and
35, these policies also require the highest policy effort; (iv) two-phase
policies prescribing more frequent screening early in life and policies
prescribing more frequent screening later in life are both on the frontier;
and (v) screening policies that stop screening early tend to result
in higher mortality risk.

Johnie Rose, MD, Rachel Molnar, Brook Watts, MD, and Mendel E. Singer,
PhD. Case Western Reserve University School of Medicine, Cleveland, OH
Purpose: To estimate the cost-effectiveness
and mortality reduction associated with implementation of a rotavirus
vaccination program in India.
Methods: We compared three strategies: no vaccination, 1- and 2-dose
vaccination with Rotarix - a new live attenuated rotavirus vaccine.
We assumed the doses would be administered through an existing immunization
program with known coverage rates. Published cumulative incidences of
infection were used to generate interval-specific probabilities of infection.
These probabilities were revised according to vaccination status using
efficacies from a clinical trial. Since no trials of Rotarix in Asia
have been completed, efficacies were estimated using India-specific
strain distributions and known strain-specific vaccine efficacies. Conditional
probabilities for hospitalization and mortality were derived from population
figures. Baseline vaccine cost used was $7/dose, the wholesale price
recently paid by Brazil. We varied this parameter from $1 to $50. A
recent trial evaluating treatment of diarrhea in Indian children provided
most treatment cost data. Since the quality-of-life impact was over
such a short period of time in relation to life expectancy of an infant,
we used life-years saved (LYS) as our effectiveness measure. The conservative
cost-effectiveness criterion used was $3,300 US (1 x India's estimated
2005 per capita GDP) per LYS.
Results: Baseline analysis yielded an incremental cost-effectiveness
ratio (ICER) of $170.56 per LYS for moving from a strategy of no vaccination
to a strategy of one dose of Rotarix, and an ICER of $350.77 per LYS
for moving from one to two doses. This corresponded to estimated annual
mortality reduction of 25,555 (27.0%) for one dose and 37,369 (39.5%)
for two doses. Estimated India-specific vaccine efficacies used were
50.6% against any infection and 59.7% against severe infection (versus
72% and 85%, respectively, from a trial in Finland). 2-dose vaccination
was preferred in one-way sensitivity analyses of all variables. Threshold
vaccine costs per dose for 1- and 2-dose strategies were $133.13 and
$65.25. For a 2-dose strategy, vaccination remained cost-effective at
efficacies as low as 6.25% against any infection and 7.35% against severe
infection.
Conclusions: Until there is a Rotavirus vaccine made from strains
isolated in India, Rotarix appears to be a cost-effective and lifesaving
intervention. This is despite the fact that differences in endemic strains
would likely make Rotarix less effective in India than trial data might
suggest.

Thomas Love, PhD1, Douglas Einstadter, MD, MPH1,
Neal Dawson, MD1, Scott Husak1, Anil Jain, MD2,
and Randall D. Cebul, MD1. (1) Case Western Reserve University
- MetroHealth Medical Center, Cleveland, OH, (2) The Cleveland Clinic Foundation,
Cleveland, OH
Purpose: In cluster-randomized trials
(CRTs), identifying clusters that are balanced on key features before
assigning them to study groups is critical for fair and powerful comparisons.
The key measure of balance in CRTs is the intra-cluster correlation coefficient
(ICC), with better values being closer to zero, and larger values associated
with significantly reduced power relative to a randomized controlled trial
of the same size (where treatment allocation occurs at the patient level.)
This report demonstrates the use of EMR data in executing a well-balanced
design for a CRT of clinical decision support (CDS).
Methods: The Diabetes Improvement Group – Intervention Trial (DIG-IT)
compares the impact of alternative approaches to CDS on the care and
outcomes of 15,000 diabetic patients cared for by 220 primary care physicians
(PCPs) in 24 diverse clinical practices of 2 health care systems. DIG-IT
interventions apply to practices, but outcomes (diabetes-related parameters,
rates of appropriate tests, treatments, immunizations, and resource
use) occur at the patient level. We considered all feasible groupings
of System A's 10 practice sites into two clusters and System B's 14
sites into three clusters. Before assigning clusters to study groups,
we assembled practice-level data from each System's EMR to examine these
groupings along an array of baseline clinical, demographic, and utilization
characteristics, including trends in diabetes-related parameters. Blinded
to site identifiers, DIG-IT investigators reached consensus about the
groupings that most effectively balanced these pre-specified characteristics.
Interventions were then randomly allocated to clusters in those groupings.
Results: System A's 10 practices were split into two clusters of 5
practices (pre-intervention, 2085 and 2281 patients, respectively);
System B's 14 practices were split into three groups of 4, 6, and 4
practices (2069, 3115, and 3185 patients). ICCs for most pre-specified
characteristics within each System were below 0.005, including A1c trend
and mean, last systolic blood pressure, current smoking, "no show" rates,
and percent with ED visits in the past year. The achieved balance was
superior to that of potential groupings by demographics alone, by geography,
or unstratified practice-level randomization, and it also was excellent
for characteristics not explicitly accounted for in the design.
Conclusions: Rich data available through EMRs provide opportunities
for designing state-of-the-art community-based CRTs, including health
care delivery trials of clinical decision support.

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