Gender Differences in Hospital Survival Rates For Medicare Beneficiaries Undergoing Coronary Artery Bypass Graft Surgery: Does Hospital Performance Ranking Matter Steven D. Culler, PhD Associate Professor Rollins School of Public Health Emory University April Simon MRN President Cardiac Data Solutions Atlanta GA

To report on gender differences in risk- adjusted mortality rates by hospital performance classes based on CABG outcomes among Medicare beneficiaries. To identify the number of female Medicare beneficiary deaths that could be avoided by improving outcomes in bottom tier hospitals. Study Objectives

Medicare Provide Analysis and Review File (MedPAR): An administrative database containing demographic information, 9 diagnostic and 6 procedure (ICD-9-CM) codes, and the discharge status of all Medicare beneficiaries admitted to any U.S. hospital. Methods: Data Sources

Study Period: October 1, 2002 to September 30, 2004 (Fiscal Years 2003 & 2004). Methods: Study Period

Inclusion Criteria: All Medicare beneficiaries undergoing a CABG surgery (Procedure codes of and 36.2). Exclusion Criteria: Patients having any concomitant valve surgery (Procedure codes of ; ; ; & ). All patients in hospitals performing less than 52 surgeries per year or less than 17 surgeries on females per year. Methods: Study Population

Methods: Study Sample Final Study SampleFY-2003FY-2004 Number of Hospitals Average Hospital Volume167±123159±113 Number of Hospitalizations134,407122,231 % Male66.5%66.9%

Methods: Analytic Approach Step 1: Annual Risk-Adjusted Mortality: A logistic regression equation (controlling for up to 25 demographic and co-morbid conditions) was estimated to predict each Medicare beneficiary’s probability of experiencing in-hospital mortality for each fiscal year.

Methods: Analytic Approach Step 2: Annual Hospital Performance Tiers: Hospitals were annually ranked into quartiles based on the number of lives saved (or lost) - the difference between a hospital’s risk adjusted expected number of deaths and its observed number of deaths during the fiscal year.

Methods: Analytic Approach Step 3: Annual Hospital Risk-Adjusted Mortality Rate by Gender: A male and female risk-adjusted mortality rate was calculated for each hospital for each fiscal year.

Results: Risk-Adjusted CABG Mortality FY-2003FY-2004 All Study Hospitals:3.68%3.61% Male Rate3.17%3.09% Female Rate4.71%4.68% Gender Differential (M-F)-1.55%-1.59%

Results: Risk-Adjusted CABG Mortality Overall Rates FY-2003Hospital Performance Tier IIIIIIIV Male Rate1.24%2.19%3.59%5.68% Female Rate1.96%3.40%5.11%8.39% Differential (M-F)-0.72%-1.21%-1.52%-2.71% Overall Rates FY-2004 Male Rate1.12%2.16%3.49%5.52% Female Rate1.80%3.31%5.39%8.19% Differential (M-F)-0.68%-1.15%-1.90%-2.67%

Results: Gender Difference Between Top and Bottom Tier TopBottomp-Value FY-2003: Male Rate1.24%5.68%<0.001 Female Rate1.96%8.39%<0.001 Differential (M-F)-0.72%-2.71%<0.001 FY-2004:3 Male Rate1.12%5.52%<0.001 Female Rate1.80%8.19%<0.001 Differential (M-F)-0.68%-2.67%<0.001

Issues: Alternative Goals for Bottom Tier Hospitals 1.The females and males have the same risk-adjusted mortality rate in bottom tier hospitals; 2.The female risk-adjusted mortality rate in bottom tier hospitals improves to the average female risk-adjusted mortality rate; and 3.The female risk-adjusted mortality rate in bottom tier hospitals improves to the female risk-adjusted mortality rate in top tier hospitals.

Goal Three: Bottom Tier Equals Top Tiers Bottom Tier FemalesFY-2003FY-2004Both Years Female Hospitalizations12,21511,10023,325 Expected Female Deaths (Current Practice) 1, ,934 Goal: Female RA-Mortality rate the same in both tiers Expected Deaths Expected Deaths Avoided ,650 Percent Deaths Avoided85.3%85.4%85.3%

Female Medicare beneficiaries had significantly higher risk-adjusted hospital mortality rates than males. As one moves from the top quartile to the bottom quartile, the gender disparity in the risk-adjusted mortality rate increases. Summary:

Improvement Goal: 85.3% of expected female beneficiaries deaths could be avoided if bottom tier hospitals achieved the same risk- adjusted outcomes as top tier CABG hospitals. Summary:

Limitations: Risk-adjusted models are based on co-morbid conditions identified from ICD-9-CM codes reported in an administrative dataset. Gender differences for Medicare beneficiaries may not reflect gender differences for CABG surgery among younger patients.

Female Medicare beneficiaries should be much more selective in choosing where to have their CABG surgery performed! Conclusion

The End

Goal One: No Gender Difference in Bottom Tier Hospitals Bottom Tier FemalesFY-2003FY-2004Both Years Female Hospitalizations12,21511,10023,325 Expected Female Deaths (Current Practice) 1, ,934 Goal: No Gender Difference in Rates in Bottom Tier Expected Deaths ,306 Expected Deaths Avoided Percent Deaths Avoided32.4%32.6%32.5%

Goal Two: Bottom Tier Hospitals Improve to the Average Female Rate Bottom Tier FemalesFY-2003FY-2004Both Years Female Hospitalizations12,21511,10023,325 Expected Female Deaths (Current Practice) 1, ,934 Goal: Female Rate in Bottom Tier Improves to Average Expected Deaths ,094 Expected Deaths Avoided Percent Deaths Avoided43.9%42.9%43.4%

Methods: Analytic Approach Risk-Adjustment: Demographic Variables: VariablesAnswer Age GroupAge 65 to 69, Age 70 to 74, Age 75 to 79, and Age 80 or greater GenderMale or Female RaceWhite or Non-white

Methods: Analytic Approach Risk-Adjustment: History of Prior Procedures or Conditions: VariablesAnswer History of Prior CABGYes or No History of Prior PCIYes or No History of Prior MIYes or No History of HemodialysisYes or No

Methods: Analytic Approach Risk-Adjustment – Co-Morbid Conditions: VariablesAnswer ObesityYes or No DiabetesYes or No Chronic Obstructive Pulmonary DiseaseYes or No Current SmokerYes or No Chronic Renal FailureYes or No Chronic Liver DisorderYes or No HypertensionYes or No Heart FailureYes or No Cardiogenic ShockYes or No Aortic AneurysmYes or No

Methods: Analytic Approach Risk-Adjustment: Co-Morbid Conditions VariablesAnswer Atrial FibrillationYes or No Ventricular FibrillationYes or No Cardiac ArrestYes or No Type of Primary Acute MISTEMI NSTEMI