Selective prescribing led to overestimation of the benefits of lipid-lowering drugs.

OBJECTIVE: Observational studies have found beneficial effects of lipid-lowering drugs on diverse outcomes, including venous thromboembolism, hip fracture, dementia, and all-cause mortality. Selective use of these drugs in frail people may confound these relationships. STUDY DESIGN AND SETTING: We measured 1-year mortality in two cohorts of New Jersey residents, aged 65-99 years, enrolled in state-sponsored drug benefits programs: 112,463 persons hospitalized during the years 1991-1994 and 106,838 nonhospitalized enrollees. Use of lipid-lowering drugs and other medications, as well as diagnoses, were evaluated before follow-up. RESULTS: In age- and sex-adjusted analyses, users of lipid-lowering drugs had a 43% reduced death rate relative to nonusers among hospitalized enrollees and a 56% reduction in the nonhospitalized sample. Available markers of frailty and comorbidity predicted decreased use of these drugs. Control for the propensity to use lipid-lowering drugs attenuated but did not eliminate these effects. After such adjustment, users had a 30% reduction in death rate (95% confidence interval [CI]: 25%-35%) among hospitalized enrollees and a 41% reduction (95% CI: 35%-47%) in the nonhospitalized sample. Unmeasured frailty associated with a 26%-33% reduced odds of receiving lipid-lowering therapy could explain this effect. CONCLUSION: Frailty and comorbidity that influence use of preventive therapies can substantially confound apparent benefits of lipid-lowering drugs on outcomes.

Consistency of performance ranking of comorbidity adjustment scores in Canadian and U.S. utilization data.

OBJECTIVE: The performance of standard comorbidity scores to control confounding is poorly defined in health care utilization data across elderly populations. We sought to evaluate and rank the performance of comorbidity scores across selected U.S. and Canadian elderly populations using health care utilization databases. DESIGN: Cross-population validation study. PARTICIPANTS: Study participants were residents age 65 years or older who had prescription drug coverage through state-funded programs selected from several large health care utilization databases available to the investigators: British Columbia, BC (N = 141,161), New Jersey, NJ (N = 235,881), and Pennsylvania, PA (N = 230,913). MEASUREMENTS: We calculated 6 commonly used comorbidity scores for all subjects during the baseline year (1994 for NJ and PA, and 1995 for BC). These included scores based on diagnoses (Romano, Deyo, D'Hoore, Ghali) and prescription drugs (CDS-1, CDS-2). The study outcome was 1-year mortality. The performance of scores was measured by c-statistics derived from multivariate logistic regression that included age and gender. MAIN RESULTS: Across these 4 large elderly populations, we found the same rank order of performance in predicting 1-year mortality after including age and gender in each model: Romano (c-statistic 0.754 to 0.771), Deyo (c-statistic 0.753 to 0.768), D'Hoore (c-statistic 0.745 to 0.760), Ghali (c-statistic 0.733 to 0.745), CDS-1 (c-statistic 0.689 to 0.738), CDS-2 (c-statistic 0.677 to 0.718), and age and gender alone (c-statistic 0.664 to 0.681). Performance was improved by an average of 6% by adding the number of different prescription drugs received during the past year. CONCLUSIONS: Performance ranking of 6 frequently used comorbidity scores was consistent across selected elderly populations. We recommend that investigators use these performance data as one important factor when selecting a comorbidity score for epidemiologic analyses of health care utilization data.

Multivariate predictors of blood product use in cardiac surgery.

OBJECTIVE: To determine factors associated with an increased risk of post-cardiopulmonary bypass (CPB) blood product usage in adult cardiac surgical patients. DESIGN: Prospective observational study. SETTING: Academic hospital. PARTICIPANTS: Patients undergoing cardiac surgery with CPB were studied over a 7-month period. INTERVENTIONS: The outcomes studied were receipt of more than 2 U of packed red blood cells (PRBCs), receipt of any other blood component products (cryoprecipitate, fresh-frozen plasma [FFP], or platelets), or surgical re-exploration for bleeding. Preoperative and intraoperative risk factors for bleeding were analyzed. MEASUREMENTS AND MAIN RESULTS: Increased age and preoperative creatinine level, low body surface area, preoperative hematocrit, nonelective surgery, lower temperature on bypass, and duration of bypass were associated with an increased risk of transfusion of >2 U of PRBCs. Low body surface area, repeat surgery, nonelective surgery, and CPB time were associated with transfusion of platelets, fresh-frozen plasma, or cryoprecipitate and/or surgical re-exploration. The following factors were associated with neither transfusion of more than 2 U of PRBC nor transfusion of platelets, FFP or cryoprecipitate, or surgical re-exploration: gender, preoperative international normalized ratio, preoperative antiplatelet medications, and preoperative intravenous heparin. CONCLUSION: Therapies aimed at reducing transfusion of blood products should be aimed at those patients with low body surface areas, baseline anemia, and those undergoing long or repeat surgeries.