Racial Differences in the
Impact of HMO Coverage of
Diabetes Blood Glucose
Monitors on Self-Monitoring
Connie A. Mah, M.S.
Department of Ambulatory Care & Prevention
Harvard Medical School & Harvard Pilgrim Health Care
cmah@fas.harvard.edu
Acknowledgements
z Co-Authors:
z Stephen B. Soumerai, ScD
z Alyce S. Adams, PhD
z Dennis Ross-Degnan, ScD
z Funders:
z AHRQ
z Harvard Pilgrim Health Care Foundation
z Consultants:
z Fang Zhang, PhD
z John D. Piette, PhD
z James Meigs, MD, MPH
Background
Coverage Policy
z Disparities in diabetes health & health
z Objective
z To reduce cost as a barrier
z To increase access to high quality care
care use
z
z
Blacks have worse glycemic control
Blacks at greater risk of adverse outcomes
z Differences in diabetes quality of care
& self-management
z
z
Blacks receive lower quality of care
Blacks face greater barriers to self-management
z Mandated in over 38 states
z Provision of glucose monitoring devices &
supplies
z Findings from parent evaluation study*
z Increased rates of SMBG
*Soumerai, Mah, Zhang, et al., Archives of Internal Medicine 2004 (164(6):645-52)
Key Research Questions
Purpose
z Does this policy have the potential to
z To determine whether policy increased
narrow some of the racial disparity in
diabetes self-management?
z Does providing free home glucose
monitors have differential impacts on selfmonitoring for black and white diabetes
patients?
initial trials of self-monitoring among black
versus white patients
z To investigate whether patients who
initiated self-monitoring after the policy
continued to self-monitor thereafter
1
Research Design & Setting
HPHC Coverage Policy
z Research Design
z Start of Implementation: Oct 1,1993
z
Longitudinal, retrospective cohort analysis
z Study Setting
z
z
Harvard Vanguard Medical Associates (HVMA)
Harvard Pilgrim Health Care (HPHC)
Study Cohort
z Objective
z To motivate diabetes patients to start monitoring their
blood glucose
z Policy Benefits
z Provision of glucose monitoring devices
z Self-management training & education
z Lower copay for up to 3 months’ supply of test strips
(≤$5/script)
HVMA Data Sources (1992-1996)
Race
Identification
z Definition of Diabetes:
≥ 1 hospital discharge Dx; or
≥ 2 outpatient Dx; or
z ≥ 1 insulin or oral sulfonylurea Rx
z
HbA1c Lab
Results
Ambulatory
Medical Records
z
z Black or White race only
Clinical
Encounters
PATIENT
STUDY ID
z Continuous enrollment (1992-1996)
Pharmacy
Claims
Dispensed
Test Strips
Drug
Therapy
Membership/
Enrollment
z N=2,275 adult patients
Demographic
Info
Days
Enrolled
Census File
Home Address
(linked by census
block group)
Key Measures
Main Analytical Methods
z Main independent measure
z Race (black v. white)
z Outcome measures
z Incidence of SMBG (≥1 strip)
z Discontinuation of SMBG (>180 days w/out strips)
z Kaplan-Meier & Log-Rank Tests
z Covariates
z Fixed (age, sex, census-derived median HH income &
educational level, drug type, BMI, HbA1c test, primary
health site)
z TimeTime-Varying (mean HbA1c values in prior month, #
MD visits per month)
z
z
Cumulative rates of initiation of SMBG
Cumulative rates of discontinuation of SMBG
z Extended Segmented Cox Models
Adjusting for patient-level fixed & time-varying
covariates
z Relative (hazard) rates of initiation of SMBG
(blacks relative to whites)
z
2
Pre-Policy Patient Differences
Any
Insulin
Black
White
(n=264) (n=613)
Oral Sulfonylurea
Only
Black
White
(n=250) (n=739)
Female
63.3%
50.4%
57.6%
44.0%
Mean Age
52±12
52±14
53±11
60±11
Mean BMI
32.7±7.1 30.5±7.5 32.0±6.3 32.1±7.2
Mean HbA1c
9.5±1.7
9.0±1.4
9.1±1.9
8.1±1.4
% Any SMBG
64.8%
77.8%
34.0%
30.8%
Initiation of SMBG
Bold denote p<0.05
Any Pre-Policy Oral
Treatment (N=904)
Any Pre-Policy Insulin
Treatment (N=567)
0.8
phase-in
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
Est. Haz Ratio
95% CI
1.09
0.84,1.40
1.35*
1.05,1.72
Pre-Policy Difference
1
(Black vs. White)
Post-Policy Difference
(Black vs. White)
phase-in
Controlling for age, glycemic control, time-dependent drug use, and timedependent number of physician visits
Apr-95
Dec-94
Aug-94
Apr-94
Dec-93
Aug-93
Apr-93
Dec-92
Aug-92
Apr-92
Apr-95
Dec-94
Aug-94
Apr-94
Dec-93
Aug-93
Apr-93
Dec-92
Aug-92
Apr-92
Censoring at first insulin use or never initiated SMBG
* p <0.05
Black
White
Post-Policy SMBG Initiators
Discontinuation of
SMBG
% SMBG Discontinuation
% with SMBG
1
100
90
80
70
60
50
40
30
20
10
0
Black (n=59)
White (n=134)
6 Months
12 Months
18 Months
Months since SMBG Initiation
p<0.05
Discontinuation = >180 days without test strip use
3
Summary
Limitations
z Trials of self-monitoring in post-policy
z Missing race data
Î increase in SMBG
Î greater for blacks on oral therapy
z Persistence after initiation of SMBG in
post-policy
Î short-lived
z Important unmeasured factors
Socio-cultural factors (attitudes, perceptions,
cultural beliefs/values)
z Duration of illness
z Intensity of medication use
z
z Single HMO
Take Home Points
z Coverage is effective in engaging patients
in SMBG particularly blacks
z Sustainability must be addressed
z Additional interventions may be necessary
to improve long-term adherence and
clinical outcomes
4