RACIAL DISPARITIES IN PRESCRIPTION DRUG UTILIZATION AN ANALYSIS OF BETA-BLOCKER AND STATIN USE FOLLOWING HOSPITALIZATION FOR ACUTE MYOCARDIAL INFARCTION

JEROME WILSON, MA, Ph.D. Associate Professor Department of Family Medicine and the National Center for Primary Care Morehouse School of Medicine Atlanta, GA June 24, 2004

BACKGROUND Long-term beta-blocker drug treatment is recommended following acute myocardial infarction (AMI) (Ryan 1999 For many patients, lipid-lowering therapy is also recommended for secondary prevention (Ryan 1999; Qurishi 2001) Disparities in the use of cardiovascular procedures have been observed by gender and race/ethnicity (Ding 2003; Giles 1995; Petersen 1194) Research on disparities in drug use for cardiovascular conditions is more limited

OBJECTIVE To assess whether the use of beta-blockers and statins following hospitalization for an acute myocardial infarction (AMI) varies by race/ethnicity among Medicaid recipients

METHODS PATIENTS Patients were selected if they were: > 18+ years of age > Hospitalized with AMI (ICD-9-CM 410.XX) between January 1, 1998 and December 31, 2000 and > Eligible for non-capitated medical and pharmacy services for at least 3 months after their hospitalization

DATA SOURCES Study patients were drawn from a 20% random sample of California Medicaid “Medi- Cal” recipients (approximately 1.3 million recipients) from four files: > Inpatient medical services > Prescription drugs > Outpatient medical services > Eligibility (e.g., age, gender, race, monthly eligibility status)

OUTCOME MEASURES The likelihood of being treated with beta- blockers or statins within 30, 60, and 90 days following a live discharge after AMI

DATA ANALYSIS Unadjusted odds ratios for treatment with beta- blockers or statins within 30, 60, and 90 days of the inpatient stay were assessed descriptively by race/ethnicity Adjusted odds ratios for treatment with beta-blockers or statins within 90 days for each race/ethnicity category (versus white recipients) were estimated via logistic regression controlling for patient demographics and comorbidities

RESULTS Patient Characteristics We identified 2,069 patients who met the cohort selection criteria, with a mean age of 71 years; 14% were African-American, 23% were Asian, 5% were Hispanic, and 58% were white

Table 1. Sociodemographic characteristics of patients hospitalized for myocardial infarction CharacteristicStudy Patients (n=2,069) Age Less than % % % % Mean ± SD 71.3 ± 13.0 Percent male 45.5 Race/Ethnicity African American 13.9 Asian/Pacific Islander 22.6 Hispanic 5.2 White 58.3

RESULTS (2) The mean Charlson comorbidity index was 1.8, The most common Charlson conditions included CHF (26%), diabetes (25%), COPD (18%), vascular disease (14%), and renal disease (6%) Hypertension was diagnosed in approximately one-third of the study patients

Table 2. Comorbid conditions for patients hospitalized for myocardial infarction MeasureStudy Patients (n=2,069) Selected Charlson Comorbidities (%): Congestive heart failure 26.0% Vascular Disease 14.0% COPD 17.8% Diabetes 25.0% Renal disease 6.2% Any malignancy 2.3% Hypertension 32.1% Hyperlipidemia 6.1%

RESULTS (3) Between 30% and 50% of patients were treated with beta-blockers and fewer (13% to 36%) with statins, depending on race/ethnicity and the number of days post hospitalization For both therapies, African American and Hispanic patients had lower treatment rates relative to Asians and whites

Figure 1. Percent of patients receiving beta- blocker therapy following MI, by race/ethnicity Source: California Medicaid program 1998 to 2000.

Figure 2. Percent of patients receiving a statin medication following MI, by race/ethnicity Source: California Medicaid program 1998 to 2000

RESULTS (4) Factors associated with a decreased likelihood of beta-blocker therapy included being African American and increasing age Beta-blocker therapy was more likely among patients diagnosed with hypertension and hyperlipidemia and those with higher Charlson comorbidity scores

Relative Odds (95% CI) Less likely to be treated Figure 3. Factors associated with beta-blocker therapy within 90 days following MI More likely to be treated Source: California Medicaid program 1998 to * Charlson comorbidity index

RESULTS (5) Factors associated with a decreased likelihood of statin therapy included being African American or Hispanic and increasing age Statin therapy was more likely among patients diagnosed with hyperlipidemia

Relative Odds (95% CI) Less likely to be treated Figure 4. Factors associated with statin therapy within 90 days following MI More likely to be treated Source: California Medicaid program 1998 to * Charlson comorbidity index

LIMITATIONS Validity of ICD-9CM codes to confirm diagnosis Limited geographical diversity Further research on pharmacotherapy is needed to better understand the observed disparities

SUMMARY In this Medicaid population, a relatively low proportion of patients were dispensed beta- blockers or statins following an AMI hospitalization African-Americans and to a lesser extent, Hispanics were the least likely to receive treatment