While the rates of hospitalization for Medicare fee-for-service beneficiaries with acute MI (AMI) have dropped significantly between 2002 and 2007, researchers found that these rates varied based on demographics, particularly race and gender, according to a study published online March 8 in Circulation.
“Unfortunately, the United States lacks a national surveillance system for assessing the incidence of AMI,” the authors wrote.
To alleviate this lack of data, Jersey Chen, MD, of the Yale University School of Medicine in New Haven, Conn., and colleagues used data from the Medicare Provider Analysis and Review database to evaluate whether the rate of AMI hospitalizations had dropped in the elderly population.
“Evaluating trends in AMI incidence for the elderly warrants particular attention because cardiac risk factor management is more challenging for these patients. Control of hypertension declines as patient age increases, particularly for women,” the authors wrote.
During the study, researchers controlled for age, sex and race. Additionally, rates for AMI hospitalization were determined using a beneficiary denominator file and calculated annually per 100,000 beneficiary-years with statistical analysis.
Of the beneficiaries, the denominator ranged from 28.2 million in 2002 to 27.8 million in 2007 and patients had a mean age of 75.3 years. Fifty-eight percent of the beneficiaries were women, 8 percent were black and 6 percent were reported being of a different racial or ethnic group.
Researchers found that from 2002 to 2007, the rates of hospitalization for AMI declined from 1,131 per 100,000 beneficiary-years to 866 per 100,000 beneficiary-years, respectively (absolute decline of 265 per 100,000 beneficiary-years; relative decline of 23.4 percent).
Prior to controlling for age, sex and race, the average annual decrease in rates of hospitalizations were recorded at 5.4 percent compared to 5.8 percent after adjustment. Within the five-year timeframe, AMI hospitalization rates based on sex declined 24.3 percent for men and 23.1 percent for women. Additionally, in regard to race, results showed that white men saw a greater decline in AMI hospitalizations compared to black men: 1,389 to 1,050 per 100,000 beneficiary-years and 1,073 to 880 per 100,000 beneficiary-years, respectively.
White women also saw less of a decline between 2002 and 2007, from 994 to 762 per 100,000 beneficiary-years.
“The finding that black men and women experienced a lower decline in AMI hospitalization rates than their white counterparts raises the concern that efforts to control coronary artery disease risk factors may be less effective for black patients,” the authors wrote.
The study showed that rates of recurrent hospitalization for AMI represented 6.9 percent of total AMI hospitalizations in 2002 compared to 5.1 percent in 2007.
Additionally, the rates of AMI hospitalizations decreased more rapidly than the rates of other comorbidities such as heart failure, pneumonia, chronic ischemic heart disease/atherosclerosis, cardiac dysrhythmias and osteoarthritis.
The authors provided several explanations that could be attributed to the decline rates of AMI hospitalizations: changes to the sensitivity of ICD-9-CM codes, increases in out-of-hospital sudden cardiac death, and the greater use of treatments and management of risk factors.
“Further surveillance of AMI trends is warranted to ensure that AMI incidence continues to decline and that all demographic groups benefit equally,” the authors concluded.