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Drug Characteristics Associated with Medication Adherence Across Eight Disease States PAWLOSKI
1. DRUG CHARACTERISTICS ASSOCIATED
WITH MEDICATION ADHERENCE
ACROSS EIGHT DISEASE STATES
Pamala A. Pawloski, PharmD1,2; Richard J Bruzek, PharmD2; Brita Hedblom1;
Steve Asche, MA1; Dana Meier, PharmD3; Cheri Rolnick, PhD, MPH1
1
HealthPartners Research Foundation, 2HealthPartners Pharmacy Services, 3Novartis Pharmaceutical
Corporation
HMORN Annual Meeting Wednesday, May 2, 2012, Seattle, WA
2. Background
Medication non-adherence shown to be universally suboptimal
and believed to be a key factor in achieving therapeutic goals
Non-adherence represents a multifaceted challenge among
patients and providers: leading to poor outcomes,
compromised health and serious economic consequences
Determinants of non-adherence previously described as health
system, social/economic, therapy-related, condition-related,
and patient-related
To date, the impact of drug characteristics on medication
adherence has not been studied across multiple disease states
3. Study Objective
To describe medication adherence by drug
characteristics across 8 different disease states:
drug class,
generic utilization,
average out-of-pocket cost/prescription
To identify potential drug-specific factors by
disease that may serve as targets for future
intervention
4. Methods
Retrospective analysis of patients with a single
diagnosis and oral medication for the following
conditions:
•Asthma/COPD
•Cancer
•Depression
•Diabetes
•Hypercholesterolemia
•Hypertension
•Multiple sclerosis (MS)
•Osteoporosis
5. Methods
This study was conducted by HealthPartners
Research Foundation
Integrated health system including 3 owned hospitals
and 27 owned clinics
15 in-clinic pharmacies and a mail order pharmacy
Serve >750,000 members
Included all patients > 18 years with 1 of 8 medical
conditions described above
6. Methods
Patient records were identified by ICD-9 DM for
diagnosis and GPI code for 128 medications of
interest through claims occurring between January
1, 2007 and March 31, 2009
• Diagnosis of interest must have occurred within 24
months of the most recent prescription fill
• A minimum of 2 prescription medication fills for at
least a 28-day supply
7. Methods
Adherence was calculated by the Medication
Possession Ratio (MPR) for each patient based on
prescription fills within a 12-month window during
the study period
Binary adherence (MPR >80%) by drug
characteristics within condition were tested with
contingency tables and chi-square tests
8. Methods
Analysis was adjusted for sex, race, age,
proportion of adults with high school education,
and median income
Logistic regression analysis was conducted to
examine predictors of adherence
9. Patient characteristics for patients with one
condition and one medication (n=14,875)
Total
%
N=14,875
Female 60.9
Race/ethnicity
White 82.8
African Am. 5.6
Asian 2.8
Hispanic 1.6
Am. Indian 0.5
Other 0.7
No answer 6.0
Age
18-49 30.4
50-59 26.2
60-69 20.7
70+ 22.7
Proportion of adults in living area
with a high school education
<88% 25.6
88-<93% 27.1
93-<96% 21.9
96%+ 25.5
Median=92.7%
Median income of families in
living area $64,500
10. Drug characteristics within condition
Asth/
Total Hyperten Depress Hyperlipid Diabetes Osteo Cancer MS
COPD
N=14,875 N=5,440 N=4,349 N=2,731 N=590 N=521 N=156 N=81
N=1,006
On
formulary 98.3 98.9 98.2 98.6 97.7 99.3 91.8 96.8 96.3
drug (%)
On
generic 75.7 91.6 74.6 66.7 22.8 85.6 78.9 41.7 0
drug (%)
Mean member amount paid per 30 days
0-$5 32.8 49.0 22.8 33.9 12.7 17.3 8.5 7.1 8.6
>$5-$12 39.1 38.2 46.4 38.0 16.2 52.4 31.5 27.6 8.6
>$12-$22 15.2 7.9 19.1 13.8 24.4 23.2 38.2 27.6 8.6
>$22-$50 11.2 4.5 10.6 12.6 39.6 6.1 18.8 31.4 45.7
>$50 1.6 0.4 1.2 1.5 7.2 1.0 3.1 6.4 28.4
15. Binary drug adherence (MPR >=80%) by drug
class, within condition
# adherent patients/
Unadjusted
Condition, Drug class (cont) # patients taking the
%
medication
Diabetes
Thiazolidinediones 41/56 73.2
Sulfonylureas 107/180 59.4
Biguanides 188/319 58.9
Antidiabetic combinations 8/15 53.3
GLP-1 receptor antagonists 8/20 40.0
Osteoporosis**
Bone density regulators 373/478 78.0
Hormone receptor modulators 15/20 75.0
Calcium 11/23 47.8
Cancer*
Antineoplastic hormonal agents/hormone 117/126 92.9
receptor modulators
Antineoplastic agents 24/30 80.0
16. Limitations
Limited population to one diagnosis/medication to
identify to evaluate least-confounded population
Small sample size occurred in some cells (across
member costs and some disease states)
Generalizability may be limited due to the study
population occurring within an integrated health
system
17. Conclusions
Variation in adherence rates by drug class
underscores the need to study adherence and
outcomes by both disease state and drug class
Future steps include a continuous analysis of
adherence to determine changes across the
adherence spectrum by disease and drug class
Correlating adherence to clinical outcomes is needed to
fully understand the meaning of adherence measures
20. MPR
Patient MPR = [(Σ Days Supplied – Days Supply of
Last Fill) / (LAST Fill Date – FIRST Fill Date)] * 100
Mean MPR = (Σ Patients’ MPR / Number of patients
in the analysis) * 100