ispor 11 th annual international meeting this study was funded by pfizer, inc

THOMSON SCIENTIFIC & HEALTHCARE

ISPOR 11th Annual International Meeting This study was funded by Pfizer, Inc.May 24, 2006

The Effects of Statin (HMG-CoA Reductase Inhibitor) Copayments and Statin Adherence on Medical Care and Expenditures

Teresa B. Gibson1, Ph.D.; Tami L. Mark1 Ph.D., MBA; Kirsten Axelsen2, MS; Joan A. Mackell2, Ph.D.; Heidi King2, MS; Onur Baser1, Ph.D.; Kimberly A. McGuigan2, Ph.D., MBA

1 Thomson Medstat, Ann Arbor, MI2 Pfizer, Inc., New York, NY

Copyright 2006 Thomson Medstat2


Introduction• HMG-CoA reductase inhibitor (“statin”) therapy is a widely accepted

treatment for patients with high cholesterol.

• Clinical trials report benefits such as reductions in mortality and morbidity from statin therapy (e.g., National Cholesterol Education Program(NCEP) Expert Panel 2002, and Simes et al. 2002).

• The extent of cardiovascular risk reduction can increase in proportion to the amount of time on statin therapy (Simes et al. 2002)



Introduction (continued)• Prescription drug copayments have increased as employers and other plan

managers attempt to contain prescription drug costs. (Kaiser Family Foundation and the Health Research and Educational Trust 2005)

• Cost-sharing is likely to continue to rise. Many firms intend to continue to increase cost-sharing in the near future. (Kaiser Family Foundation and the Health Research and Educational Trust 2005; PriceWaterhouseCoopers 2005)

• Higher prescription drug copayments may lead patients with chronic conditions to reduce utilization of maintenance drugs (Bierman and Bell 2004; Gibson et al. 2005)

• Higher statin copayments are associated with a reduction in compliance for new users of statins. Higher statin copayments and lower levels of statin compliance are also related to lower levels of outcomes (e.g., LDL-C goal attainment and hospitalization). (Goldman et al. 2005, Schultz et al. 2005)



Study Aims

1. To estimate the effects of statin copayments on statin adherence for statin users, and,

2. To estimate the effects of statin adherence on expenditures and utilization



Data Source• MarketScan Commercial Claims and Encounter Database and

Medicare Supplemental and Coordination of Benefits Database for services provided from January 1, 2000 through December 31, 2003.

– Contains the healthcare experience of individuals with employer-sponsored health care insurance and Medicare supplemental insurance in the United States

– Includes enrollment information and inpatient, outpatient and pharmacy claims



Inclusion Criteria and Study Sample• Inclusion Criteria:

– 18 years of age or older – Continuously-enrolled from 2000 through 2003 – At least one statin prescription fill January 2001 through June 2001– No indication of pregnancy during the study time frame

• Study Sample Construction:– Continuing users: Filled a statin prescription in 2000– New Users: Filled a statin prescription in Jan-June 2001 and at least one

year prior without a statin fill– Each patient was followed July 2001 through December 2003

• Continuing Users: n=93,296 patients

• New Users: n=24,113



Measures• Adherence to Statin Therapy (July 2001 – December 2002)

– Medication Possession Ratio (MPR) calculated by assessing whether statins were on-hand each day, % of days with statins on-hand

– Adherent if MPR > 80%

• Expenditures and Utilization (January - December 2003)– Expenditures –

• Total (Medical plus prescription drug)• Medical• Prescription Drug

– Utilization (1/0 variables)• Physician Office Visit• Emergency Room Visit• Hospitalization• Coronary Heart Disease-related (CHD) Hospitalization



Explanatory Variables• Patient Cost-Sharing

– Statin cost sharing amount (USD $ 2003 per day) – Office Visit cost sharing amount (USD $ 2003 per visit)

• Sociodemographic - Age, Gender, US Census Region, Urban Area, Household Income and % with College Degree (by ZIP code via Census information)

• Health Plan Type – (e.g., HMO, PPO, POS, Comprehensive)

• Type of Provider (prior 12 months)

• Medication (prior 12 months) - Number of prescriptions, Any use of mail order

• Severity/Comorbidity (prior 12 months)– Acute Myocardial Infarction, Angioplasty, Coronary Bypass Surgery, Chronic

Ischemic Heart Disease (IHD), Coronary Atherosclerosis, Other IHD, Hypertension– Anxiety, Dementia, Depression



Multivariate Analysis-Two Stage Residual InclusionStage 1: Adherence, Logistic Regression

• Pr(Adherencei|x) = F(0 + 1sociodemographici + 2plani + 3providerip + 4medicationip + 5severityip + 6comorbidityip + 7cost-sharingi)

Stage 2: Utilization and Expenditures

• G(Expenditurei) = ln(0 + 1sociodemographici + 2plani + 3providerip + 4severityip + 5comorbidityip + 6Adherence + 7 û1 )

• P(Utilizationi|x) = F(0 + 1sociodemographici + 2plani + 3providerip + 4severityip + 5comorbidityip + 6Adherence + 7 û1)

i is patient, p is a 12 month lag, F is the cumulative logistic function and G is the gamma distribution

^

ν



Selected CharacteristicsContinuing Users New Users

Characteristic n=93,296 n=24,113

Female (%) 44.5 50.2

Age (y) 64.1 11.2 58.8 12.6

Insurance Plan Type (%)

Comprehensive 28.9 26.2

HMO 3.2 3.9

Capitated POS 33.0 26.3

Non-Capitated POS/EPO 6.4 8.5

Preferred Provider Org. 28.8 35.1

Statin Copayment ($/day) $0.40 0.20 $0.43 0.17



Selected Characteristics (continued)Continuing Users New Users

Characteristic (%) (12 month lag)

n=93,296 n=24,113

AMI 1.6 1.4

Angina 18.9 17.8

CABG 0.9 0.7

Chronic IHD 5.0 2.9

Coronary Atherosclerosis

24.8 15.3

Other IHD 3.4 2.5

PCTA 0.6 0.5



Measures of Adherence, Utilization and ExpenditureMeasure n=93,296 n=24,113

Adherence/MPR (July 2001-Dec 2002)

0.58 0.49 0.28 0.45

Utilization and Expenditures (2003)

Total Expenditures $6,589.70 7893.24 $5,798.63 8485.10

Medical Expenditures $3,513.53 6866.97 $3,323.55 7438.78

Prescription Drug Expenditures $3,076.17 2598.15 $2,475.08 2767.20

Office Visits 0.93 0.26 0.90 0.30

ER Visits 0.22 0.41 0.21 0.41

Hospitalizations 0.14 0.35 0.12 0.32

CHD-Related Hospitalizations 0.05 0.23 0.04 0.20



Effects of Copayments on Adherence-Continuing Users

54

55

56

57

58

59

60

61

LowCopayment($.19/day)

MediumCopayment

($.42)

HighCopayment

($.63)

Pred

icte

d Pr

obab

ility

of A

dher

enceSelected

EffectsAdjusted Odds Ratio 95% CI

Female (0.863, 0.914)

Age, y <=65 (1.025, 1.03)

Age, y over 65 (0.982, 0.988)

Statin Copayment

(0.632, 0.735)

Higher copayments are associated with lower levels of adherence

All p<.01, n=93,296



Effects of Copayments on Adherence-New Users

24

25

26

27

28

29

30

31

LowCopayment($.19/day)

MediumCopayment

($.42)

HighCopayment

($.63)

Pred

icte

d Pr

obab

ility

of A

dher

enceSelected

EffectsAdjusted Odds Ratio 95% CI

Female (0.717, 0.813)

Age, y <=65 (1.03, 1.04)

Age, y over 65 (0.962, 0.976)

Statin Copayment

(0.621, 0.918)

Higher copayments are associated with lower levels of adherence

All p<.01, n=24,113



Effects of Adherence on ExpendituresContinuing Users

Expenditures Coefficient Standard Error p-value

Total Expenditures 0.179 0.117 0.125

Medical Expenditures

-0.256 0.199 0.197

Prescription Drug Expenditures

0.703*** 0.069 0.000

Higher levels of adherence are associated with higher prescription drug expenditures, lower (nonsignificant) medical expenditures and no change in total medical expenditures.

* p<.10,** p<.05, *** p<.01



Effects of Adherence on ExpendituresNew Users

Expenditures Coefficient Standard Error p-value

Total Expenditures -0.088 0.109 0.423

Medical Expenditures

-0.150 0.179 0.402

Prescription Drug Expenditures

0.065 0.081 0.426



Effects of Adherence on Utilization – Continuing Users

Coefficient Adjusted Odds Ratio 95% CI

Office Visits 0.349 (0.688, 2.876)

ER Visits -1.514*** (0.133, 0.364)

Hospitalizations -.566* (0.308, 1.048)

CHD-Related Hospitalizations

-1.688*** (0.072, 0.480)

* p<.10,** p<.05, *** p<.01

Higher levels of adherence are associated with a decreased likelihood of ERvisits, hospitalizations and CHD-related hospitalizations



Effects of Adherence on Utilization – New Users

Coefficient Adjusted Odds Ratio 95% CI

Office Visits 0.927** (1.228, 5.195)

ER Visits 0.059 (0.648, 1.737)

Hospitalizations -0.076 (0.497, 1.729)

CHD-Related Hospitalizations

-0.882* (0.158, 1.082)

* p<.10,** p<.05, *** p<.01

Higher levels of adherence are associated with an increased likelihood of an office visit, no change in ER visits or hospitalizations and a decreased likelihood of CHD-related hospitalizations



Effects of Adherence on Utilization – Continuing Users

0

0.2

0.4

0.6

0.8

1

Physician OfficeVisits

ER Visits Hospitalization CHD-RelatedHospitalization

25% Adherent Adherent



Effects of Adherence on Utilization – New Users

0

0.2

0.4

0.6

0.8

1

Physician OfficeVisits

ER Visits Hospitalization CHD-RelatedHospitalization

25% Adherent Adherent



Limitations• Administrative Data

• Continuously-enrolled population with employer-sponsored insurance

• Selection

• Sensitivity Analysis



Summary and Conclusions• In this large cohort of statin users enrolled in employer-sponsored

plans, prescription drug copayments are a financial barrier to statin adherence.

• For continuing/prevalent users of statins, statin adherence is related to higher prescription drug expenditures and a nonsignificant offset in medical expenditures. Total expenditures are not significantly different.

• For new/incident users of statins, statin adherence is not associated with changes in medical or prescription drug expenditures.



Summary and Conclusions• For continuing users of statins, lower statin copayments are associated

with higher levels of statin adherence. Total costs may not change, but fewer negative events (ER visits, hospitalizations and CHD-related hospitalizations) occur.

• Reducing patient cost-sharing for a maintenance drug regime may be an effective intervention.

ispor 11 th annual international meeting this study was funded by pfizer, inc

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