AF-associated Stroke

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AF-associated Stroke

N D P S S

A Cost-Comparison Study:

The Economic Burden of

Atrial Fibrillation & Stroke

The North Dublin Population Stroke Study

N Hannon, S Smith, D Ní Chróinín, E Callaly,

M Marnane, Á Merwick, Ó Sheehan, J Duggan,

L Kyne, E Dolan, A Moore, S Murphy, PJ Kelly

Conflict of Interest/Disclosures: None


AF and Stroke

Substantial societal impact of Atrial Fibrillation

(AF), particularly due to stroke

AF is associated with a profile of severe,

recurrent, and disabling stroke, particularly in

older adults 1

Accurate health economics data are important

for health service planning and development of

clinical policies and national strategies

1. Hannon N, et al. Stroke associated with atrial fibrillation - incidence and early outcomes in the North

Dublin Population Stroke Study. Cerebrovasc Dis 2010; 29(1):43-49


AF and Stroke

Studies of insurance databases reported higher

total healthcare costs associated with AF 1

2 hospital-based studies in patients with AFassociated

stroke report higher inpatient costs 2,3

There is a lack of national cost of illness

estimates, and little data exist to quantify the

economic impact of AF-associated stroke

1. Caro JJ. An economic model of stroke in atrial fibrillation: the cost of suboptimal oral anticoagulation.

Am J Manag Care 2004; 10(14 Suppl):S451-58

2. Bruggenjurgen B, et al. The impact of atrial fibrillation on the cost of stroke: the Berlin acute stroke

study. Value in Health 2007; 10 (2):137-143.

3. Ghatnekar et al. The effect of atrial fibrillation on stroke-related inpatient costs in Sweden: a 3-year

analysis of registry incidence data from 2001. Value in Health 2008;11(5):862-868.


Specific Aims

In a rigorous population-based prospective cohort

study (two-year follow-up) to :

1. investigate the total healthcare costs (direct and

indirect) of AF-associated stroke

in the acute hospitalisation period (index event)

in the community post hospital-discharge

in any subsequent hospitalisations post-index

stroke

2. compare to healthcare costs of non-AF-associated

stroke


Methods – the NDPSS

Population based cohort study of TIA and Stroke

in North Dublin (using District Electoral Division

system - total population 294,529)

Multiple validated 1 overlapping (“hot” and “cold”

pursuit) hospital and community sources were

used for case ascertainment

Follow up at 7, 28 and 90 days, 1 and 2 yr

1. Feigin VL, Carter KV. Standards for an ideal stroke incidence study Stroke

(2004) 35: 2045 - 2047


Methodology

Societal perspective: costs associated with

stroke that are borne not only by healthcare

institutions but also to an extent by individuals

Direct costs: costs directly related to the

provision of healthcare

Indirect costs: cost of loss of productivity due

to stroke morbidity


Methodology - Direct Costs

Hospital:

First (index) stroke

Inpatient

Rehabilitation (after

initial hospitalisation)

Recurrent stroke

(


Methodology - Direct Costs

Hospital:

First (index) stroke

Inpatient

Rehabilitation (after

initial hospitalisation)

Recurrent stroke

(


Methods: Acute Inpatient Care

Casemix approach is a “top-down approach”:

allocates total hospital costs across all discharges on

the basis of casemix units rather than length of stay

Casemix unit measures the complexity (resource

use) by Diagnosis Related Group

adjusted per length of inpatient stay

The Irish national computerised system (HIPE)

facilitated data collection on hospitalised NDPSS

participants to calculate length of stay and casemix

unit data


Methods: Acute Inpatient Care

Cost per Casemix Unit

x

number of Casemix Units per patient

per episode

(e.g. index stroke)


Methods: Acute Inpatient

Rehabilitation Care

“bottom-up approach”:

cost per inpatient rehabilitation bed day

x

length of stay per patient

For NDPSS participants who received inpatient

rehabilitation care, the location and length of stay

was identified at post-stroke follow-up

Unit cost per bed-day was estimated from average

public nursing home cost (2007 prices)


Methods: Nursing Home Costs

“bottom-up approach”:

cost per week in public/private nursing home

x

Number of weeks in nursing home per patient

For NDPSS participants who were transferred to

nursing home care, the length of stay was identified

at post-stroke follow-up

Weekly Unit cost was calculated stratified by public

or private nursing and by dependency (2007 prices)


Morbidity

Methods: Indirect Costs

Adopted the human capital approach: amount of

earnings lost due to illness

Using pre-stroke employment data for NDPSS

participants (including homemakers), time lost from

work due to inpatient stay was calculated


Methods - Statistical Analysis

All analyses were conducted on Stata (v.9)

Univariate – chi-squared and Fisher exact

test (non-continuous), t-test and Wilcoxon

rank-sum test for continuous

parametric and non-parametric variables as

appropriate

Multivariate – linear regression


Results – Clinical Characteristics

Characteristic With AF

(n=177)

Age (years) mean

(range)

76.5

(44-96)

Without AF

(n=391)

68.5

(31-95)

P-value


Results – Cost of Stroke

without

AF

with AF

Median Cost in $ (2007 prices)

$17,951

$73,684 $35,407

Error Bars: 25-75% Interquartile Range


Results – Inpatient Costs

2007 prices ($) With AF Without AF pvalue

Inpatient Costs (Index

stroke, all types)

Median (25-75% IQR)

Inpatient Rehabilitation

Costs (index stroke)

Mean ± SD

Inpatient Costs (Repeat

admissions) Mean ± SD

IQR=Interquartile Range

SD=Standard Deviation

NS=non-significant

14,430

(10,411-41,487)

1,574

± 10,150

3,624

±12,272

10,753

(9,597-26,559)

717

± 5,746

1,975

± 8,549

0.002

NS

NS


Results – Inpatient Costs

Inpatient Rehabilitation Costs

(Mean)

Inpatient Readmissions Costs

(Mean)

Inpatient Costs (Mean)

+54%

+46%

Non-AF Associated Stroke

AF-associated Stroke

Mean Cost in $ (2007 prices)

+25%


Results – Nursing Home Costs

2007 prices ($) With AF Without AF pvalue

Cost of Nursing Home Care

Mean ± SD

SD=Standard Deviation

NS=non-significant

24,288

±69,418

13,147

± 52,187

0.002


Results – Nursing Home Costs

2007 prices ($) With AF Without AF pvalue

Cost of Nursing Home Care

Mean ± SD

SD=Standard Deviation

NS=non-significant

24,288

±69,418

46% greater

13,147

± 52,187

0.002


Results – Cost of Stroke

$73,684

GP Care Cost

New Prescription Medicines Costs

Morbidity Cost

Out-patient Attendance Cost

In-patient Rehabilitation Costs

Repeat Admission Costs

Community Supports Cost

In-patient Costs

Cost of Long-term Institutional Care

Mean Cost in $ (2007 prices)

Non-AF Associated Stroke

AF-associated Stroke


Results – Cost of Stroke

$73,684

GP Care Cost

New Prescription Medicines Costs

Morbidity Cost

Out-patient Attendance Cost

In-patient Rehabilitation Costs

Repeat Admission Costs

Community Supports Cost

In-patient Costs

Cost of Long-term Institutional Care

Mean Cost in $ (2007 prices)

Non-AF Associated Stroke

AF-associated Stroke


Multivariate Analysis

On MV linear regression, modelling for AF

and age:

AF was an independent predictor of

total costs (p=0.02, beta 0.09)


Multivariate Analysis

On MV linear regression, modelling for AF

and age:

AF was an independent predictor of

total costs (p=0.02, beta 0.09)

On MV linear regression, modelling for AF,

and 72-hour Rankin score:

AF was an independent predictor of

total costs (p=0.04, beta 0.09)


Discussion

In a detailed population study of all stroke

types, stroke associated with AF accounted for

a greater mean total cost in a two year period;

as compared to stroke without AF

The main driver for higher costs in AF-stroke

was the cost of inpatient hospitalisation

Hospitalisation costs were 40% higher for

inpatients with AF-stroke compared to non-AF

stroke


Discussion

Previous hospital-based studies have

demonstrated that longer inpatient stay

increased the cost of stroke associated

with AF

The results of the NDPSS demonstrate

that post-discharge costs also contribute

to the higher costs of stroke in AF,

especially nursing home care


Discussion

Detailed cost of illness studies are

important to enable economic budgeting

for the provision of essential services

AF-associated stroke should be

recognised as a substantial contributor to

healthcare costs and future stroke care

guidelines should reflect this


Acknowledgments

Economic and Social

Research Institute

Dr Samantha Smith

Brian McCarthy

HIPE Coordinators

Helen Nolan (Mater)

Des O’Toole (Beaumont)

Deirdre Hogan-Lowe

(Connolly)

Mater Hospital

Christine Mitchell (IT)

Mich Vartuli (IT)

Adele McGrane (Accounts)

North Dublin Population Stroke

Study Co-investigators &

Collaborators

Prof Peter J Kelly

Prof Sean Murphy

Collaborators at 3 North

Dublin Hospitals (Mater,

Beaumont, Connolly)

Research fellows

Research Coordinators

N D P S S


Thank You


Results – Outpatient Costs

2007 prices ($) With AF Without AF pvalue

GP Care Costs

Mean ± SD

Outpatient Attendance

Costs

Mean ±SD

New Prescription

Medicines Costs

Mean ±SD

SD=Standard Deviation

NS=Non-significant

222

± 174

1,320

± 1,554

846

± 1,014

216

± 166

1,666

± 1,533

937

± 1,059

NS

0.01

NS


Results – Community Costs

2007 prices ($) With AF Without AF pvalue

Community Services Costs

Mean ± SD

Special Equipment &

Home Modification Costs

Mean ± SD

Morbidity Costs

Mean ± SD

SD=Standard Deviation

NS=non-significant

5,555

± 13,445

2,762

± 9,036

893

± 3,205

3,854

± 11,988

2,147

± 8,367

1,142

± 4,521

NS

NS

0.07


Results – Costs of Prescriptions

Alpha Blocker

Calcium Channel Blocker

Angiotensin Receptor Blocker

ACE-inhibitor

Beta-Blocker

Diuretic

Statin

Warfarin

Dipyridamole

Clopidogrel

Aspirin

Non-AF Associated

Stroke

AF-associated Stroke

Mean Cost in $ (2007 prices)


40,000

35,000

30,000

25,000

20,000

15,000

10,000

5,000

Cost per pre-stroke medication

0

34,255

No

antithrombotic

AF-associated Stroke (n=177)

37,589

31,350

MEDIAN ($)

28,968

Antiplatelet only INR2

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