• An epidemiologic evaluation of hospitalizations of elderly Medicare beneficiaries due to adverse reactions to anticoagulant therapy using claims data

      Fitterman, Leslye K.; Speedie, Stuart M. (1995)
      The objective was to examine a representative population of elderly persons in the United States to (1) provide an estimate of the number of persons taking oral anticoagulants, (2) estimate the rate of anticoagulant adverse drug reaction (ADR) hospitalizations, (3) describe patient demographic and clinical characteristics, and (4) examine patient and provider characteristics in relation to an anticoagulant ADR. The retrospective case-control study used the Health Care Financing Administration's Medicare program claims and administrative data. The case-control subjects were "presumed" to be being monitored for anticoagulant treatment. The selection criteria excluded those with less than three prothrombin time tests PTs and no claim indicating one of the following diagnoses; pulmonary embolism, atrial fibrillation with embolism or, deep vein thrombosis. The number of subjects in the study was 1,135 cases and 7,133 controls. The estimated number of persons "presumed" to be monitored for anticoagulant therapy was 2 million. Incidence rates of ADR hospitalizations and anticoagulant ADR hospitalization per 1,000 hospitalizations were found to be 22.99 and 1.17. This study found that although anticoagulant ADRs are rare, the finding may be an underestimate. The only patient demographic characteristics found to be associated with ADRs was gender. Females were at risk for an ADR. The relationship between structure, process, and outcomes, (an effectiveness model) identified factors that increase the risk for an anticoagulant ADR hospitalization. Persons who had PTs done in physician office laboratories were at slightly greater risk for an adverse outcome than persons who had PTs done in commercial laboratories. Persons in the case-control group had a high mean number of interactions with the health care system, between 1 and 2 a week suggesting that persons on anticoagulant therapy account for a relatively high amount of utilization. Carcinoma, hypertension, renal insufficiency, congestive heart failure and hepatic disorders were confirmed as risk factors for an adverse outcome. But, because of the under-reporting of ADRs, it is likely that there is misclassification of cases as controls. Thus, there is bias towards the null for all the risk factors, and if anything, those factors associated with ADRs are underestimates.
    • Underutilization of cardiovascular medications by aged Medicare beneficiaries with heart disease

      Doshi, Jalpa A.; Stuart, Bruce C. (2003)
      Despite publication of evidence-based guidelines and numerous quality-improvement efforts, studies have documented under use of effective cardiovascular medications in a large proportion of elderly patients with heart disease. This study has two objectives. The first is to examine utilization of effective cardiovascular medications for four common conditions among a nationally representative sample of institutionalized and community-dwelling aged Medicare beneficiaries. These include: warfarin in atrial fibrillation, beta-blockers in myocardial infarction, statins in hyperlipidemia and coronary artery disease, and ACE-inhibitors in diabetes with concomitant cardiovascular risk factors. The second aim is to assess policy-relevant risk factors associated with under use of these cardiovascular medications; specifically, to examine whether the risk of under treatment varies with the presence, type, and generosity of drug coverage; beneficiary age; physician specialty; geographic location; and type of residential setting. The study also examined whether the risk of under treatment of elderly beneficiaries has decreased over time. The data source was the Medicare Current Beneficiary Survey (1997--2000) supplemented with data from Medicare claims. Descriptive as well as multivariate analyses were conducted. Propensity score techniques were used to compare underuse between community and nursing home residents. Substantial underuse of cardiovascular medications was found across the four diseases. While the use of these medications in the outpatient setting has increased between 1997 and 2000, there still remains ample opportunity for improvement. Older age was negatively associated with cardiovascular medication use across the disease samples. Type and generosity of prescription coverage was correlated with use of the expensive statins and ACE-inhibitors/ARBs, and uncorrelated with use of the cheaply available warfarin and beta-blockers. Significant geographic variation was observed in all four cardiovascular medications. No significant differences were observed in cardiovascular medication use among patients treated by generalists versus cardiac specialists. Similarly, the risk of under treatment was the same in nursing homes and in the community. These findings point towards the need for increased educational efforts directed toward the physicians as well as patients. The findings relating to prescription coverage have direct implications for the Medicare drug benefit design. Overall, the results of this study can provide guidance to researchers, policy makers, and clinicians concerned with improving the quality of cardiovascular medication use among aged Medicare beneficiaries with heart disease.