1. Sex Differences in 30-Day Readmission Risk among Young Patients with Acute Myocardial Infarction
Medstar Washington Hospital Center
November 4th 2015
Rachel Dreyer, PhD
Yale University School of Medicine
Center for Outcomes Research and Evaluation (CORE)

2. Disclosures Statement of Financial Interest
I, Rachel Dreyer, DO NOT have any relevant financial relationships to disclose at this time.

4. 1. Background
and Objectives
Photo credits: Flickr user Dan_DC

5. Young women are still virtually invisible in cardiology
Photo credits: Flickr user JimCodePoet, Huaweioz, AHA Go Red Campaign

6. The barrier of small numbers at any single institution…
Photo credits: Flickr user Bart Luyckx

7. % In-hospital Mortality
Young Women with AMI Have Higher In-Hospital Mortality NRMI N=38,478 (40% women)
24.2
21.8
21.5
Sex-Age Interaction: P<0.001
19.1
18.4
14.4
% In-hospital Mortality
2.9
10.7
9.5
8.2
7.4
5.7
4.1
2.9
Vaccarino V et al. N Engl J Med 1999;341:

8. Australia
Europe
USA
Canada
China

9. Photo credits: Flickr user Casitalboga

10. Readmission
Photo credits: Michael S. Helfenbein

11. No data on young women

12. Study Objectives
To evaluate sex differences in the rate, timing and principal diagnoses of 30-day readmission following AMI
To examine the association of sex with 30-day readmissions
To assess whether or not there is an age-sex interaction
We hypothesized that younger women (<65 years) have a higher risk of readmission than younger men, even following extensive adjustment for covariates, and similar timing of readmission, as well, and a broad range of readmission diagnoses.

13. 2. Methods
Photo credits: Flickr user Dan_DC

14. Data Source & Study Population
Healthcare cost and Utilization Project (HCUP) - State Inpatient Dataset (SID) for California (Jan 07 – Nov 09)
Administrative dataset of 42,518 patients (26% women) with acute myocardial infarction (AMI)
Inclusion criteria:
18-65 years of age
Principal discharge diagnosis of AMI
Defined by ICD-9-CM diagnostic codes of “410.xx” with exclusion of codes 410.X2, consistent with the Medicare AMI readmission measure

15. Exclusion Criteria Exclusion criteria:
Left against medical advice
Transferred to another facility
Died in Hospital
Non California residents (as subsequent readmissions may not have been captured in the state inpatient dataset)
We considered only the 1st readmission within 30-days of the index admission, as used by the CMS criteria for reporting hospital readmission performance
Planned hospitalizations were excluded

16. Statistical Analyses
Sex differences assessed via χ² and Wilcoxon Rank Sum tests
We assessed the timing of the first unplanned readmission by day (0-30) after discharge, and the principal readmission diagnoses within 30 days
A cox proportional hazards model was utilized to assess the association between sex and risk of unplanned 30-day readmission for AMI. We sequentially adjusted for the following:
Socio-demographics
Cardiovascular risk factors/conditions/procedures
Other co-morbidities
Length of stay
Discharge disposition
In the final model we tested the interaction between age and sex on 30-day readmission

17. 3. Results
Photo credits: Flickr user Dan_DC

18. Socio-Demographics on Presentation
Characteristics
Women (N=11,215)
Men (N=31,303)
Socio-Demographics (%)*
Age (Mean±SD)
White
Black
Hispanic
Other
Private health insurance
Medicare
Medicaid
54±7.5
53%
13%
21%
47%
16%
20%
14%
53±7.6
57% 6%
58%
10%
11%
19%
*All P values <0.001
Dreyer et al. Circulation. 2015;4:

19. Cardiovascular Risk Factors on Presentation
Characteristics
Women (N=11,215)
Men (N=31,303)
Cardiovascular Risk factors (%)*
Acute coronary syndrome
Congestive Heart failure
Diabetes and complications
Stroke
Anterior AMI
Angina pectoris
Valvular/Rheumatic heart disease
Arrhythmias
10%
12%
44% 1%
16% 9% 6% 5%
32% 0%
18%
14% 4%
*All P values <0.001
Dreyer et al. Circulation. 2015;4:

20. Co-morbidities on Presentation
Characteristics
Women (N=11,215)
Men (N=31,303)
Co-morbidities (%)*
Chronic obstructive pulmonary disease
Pneumonia
Asthma
Renal failure
Cancer
History of infection
Vascular/circulatory disease
Fluid/electrolyte/acid-base disorders
Dementia/Senility
Major Psychiatric disorders
Drug/alcohol abuse
16% 9% 8%
11% 3% 6%
14% 5%
10% 1% 2% 4% 7%
*All P values <0.001
Dreyer et al. Circulation. 2015;4:

21. Discharge Disposition
Characteristics
Women (N=11,215)
Men (N=31,303)
LOS/Primary Discharge Disposition (%)*
Length of stay (Mean±SD)
Routine (home)
Transfer (Skilled nursing facility/Intermediate care) Home health care
Alive but place unknown
4.9±6.4
87% 5% 7%
0.3%
4.4±5.6
90% 3% 6%
0.2%
*All P values <0.001
Dreyer et al. Circulation. 2015;4:

22. 30-Day Readmission Rate in Young Patients with AMI
Close to 2-fold higher risk of readmission
N=4, Day All-Cause Readmissions (1,736 women)
Dreyer et al. Circulation. 2015;4:

23. 30-Day Readmission Rate in Young Patients Stratified by Age
Men
Women
Dreyer et al. Circulation. 2015;4:

24. 30-Day Readmission Rate in Young Patients Stratified by Race
Men
Women
Dreyer et al. Circulation. 2015;4:

25. 30-Day Readmission Rate in Young Patients Stratified by Payer Status
Men
Women
Dreyer et al. Circulation. 2015;4:

26. Timing of Readmission Per Day (0-30) Post AMI
Dreyer et al. Circulation. 2015;4:

27. Principal Readmission Diagnoses for Cardiac Causes
Characteristics
Women (N=11,215)
Men (N=31,303)
Readmission for cardiac diagnosis (%)
Heart failure
Myocardial infarction
UA/other acute ischemic heart disease
Chronic angina/CAD*
Other congenital heart/hypertensive disease
Arrhythmias/conduction disorders
Chest pain*
Syncope*
Acute stroke/TIA
Other peripheral vascular disease
55%
13% 8% 3% 6% 2%
11% 0% 1%
59%
12% 9%
*P value <0.01
Dreyer et al. Circulation. 2015;4:

28. Principal Readmission Diagnoses for Non-Cardiac Causes
Characteristics
Women (N=11,215)
Men (N=31,303)
Readmission for noncardiac diagnosis (%)
Pleural effusion/pneumothorax
COPD*
Pneumonia
UTI and urinary system*
Renal disorders/renal failure
Anemia
Diabetes mellitus and its complications
Septicemia/shock
Hip fracture
Gastrointestinal hemorrhage
44% 0% 2% 3% 4% 1%
40%
*P value <0.001
Dreyer et al. Circulation. 2015;4:

29. Independent Association of Sex on 30-Day Readmission
Dreyer et al. Circulation. 2015;4:

30. Discussion of Findings
4. Conclusion and
Discussion of Findings
Photo credits: Flickr user Dan_DC

31. Summary of Key Findings
We observed nearly a 2-fold greater risk of readmission in younger women with AMI in comparison to younger men
The association of sex persists even following adjustment for extensive covariates, and does not vary by age
The timing of 30-day readmission was similar between sexes, and both sexes were vulnerable for a wide range of unrelated causes for readmission, a pattern consistent with the post-hospital syndrome
The key finding is that the pattern was similar in women and men, but the rate was substantively higher in women
Dreyer et al. Circulation. 2015;4:

32. Discussion
Appreciate that younger women (<65 years) represent a unique phenotype and have a higher risk for 30-day readmission
Research efforts should be focused on identifying risk factors or opportunities in care that differ between groups and that may mediate the observed disparities- to inform effective interventions
A need for continued focus on safe discharge planning and early ambulatory intervention post discharge for AMI
There is an opportunity to focus on young women, a high risk group, who are inherently more unaware of the prevalence of CAD
Dreyer et al. Circulation. 2015;4:

33. Women’s Cardiac Health
5. New Frontiers:
Women’s Cardiac Health
Photo credits: Flickr user marionzetta

34. Re-hospitalization (%)
Young Women with AMI Have Higher 12-month Readmission TRIUMPH AMI Registry N=1414 (28% women)
Re-hospitalization (%)
Dreyer R et al In progress.

35. Contact: rachel.dreyer@yale.edu
Thank you
Contact:
@DreyerRachel