AsthmaAsthma

Leslie Boss (CDC)Carlos Camargo

Denise Dougherty (AHRQ)Virginia Taggart (NHLBI)

Sandra Wilson

With Special Thanks to:Barbara DeVinney (NIH/OD)

Lawrence Fine (NIH/OD)

Outline of Presentation

• Background

• Measures

• Design 1

• Design 2

• Trade-offs Discussion

Definition of Asthma

• Chronic lung disease characterized by:– Airway narrowing that is reversible (± completely)

either spontaneously or with treatment– Airway inflammation– Airway hyper-responsiveness to a variety of stimuli.

• Episodic dyspnea with wheezing

• National Asthma Education and Prevention Program (NAEPP)

ATS, ARRD 1987

NAEPP Guidelines, 1997

• Classification of chronic asthma:– Mild intermittent asthma– Mild persistent asthma (>2 days/wk, >2 nights/mo)– Moderate persistent asthma– Severe persistent asthma

• Inhaled corticosteroids (ICS) are “preferred treatment” for all patients with persistent asthma

• 2002 Update

Potential for Improving Asthma

• ED is often used for asthma care– 2 million ED visits per year, especially Sept-Dec– Initial PEF 46% of predicted (severe)– 20% of patients admitted overnight to hospital

• Among ED patients (EMNet/MARC data):– 74% adults use ED for all “problem” asthma care– 45% adults receive all asthma Rx from ED– With PCP: 63% for problem care; 24% for all Rx

• High-risk populationwww.EMNet-USA.org

ED Patients with Acute Asthma

1996 (n=770)

1997-98 (n=4,920)

1999-01 (n=1,248)

Ever admitted for asthma (%) 54 63 64

Ever intubated (%) 15 17 17

ED visits in past year (%) 76 90 79

Used inhaled corticosteroids in past 4 weeks (%)

42

44

46

www.EMNet-USA.org

ED-Initiated Secondary Prevention

• High-risk population

• Use of ED for “problem asthma” care + asthma Rx

• What interventions are feasible in the ED setting?

Examples from EMNet:

1. ICS initiation at discharge from ED2. Asthma education programs3. Other options?

www.EMNet-USA.org

Referral from the ED

• Bridging the gap between ED and primary care

• Pilot study - how to get patients back to PCP

(Baren et al, Ann Emerg Med 2001)

• Two randomized trials:– EMNet (9 sites, funded by ACEP/EMF)– St Louis (1 site, funded by AHRQ)

• Next steps?

Research Question

Does referral of emergency department

(ED) patients with acute asthma to “asthma

centers” (i.e., dedicated clinics with asthma

specialists, asthma educators, additional

resources) improve asthma outcomes in

this high-risk population?

Overview

• Intervention would have 3 key elements:– Facilitated referral to the Asthma Center– Asthma Center management (2+ visits in 3 months)– Shared “communication form”

• 40 urban EDs & local asthma centers

• Two study designs:– Quasi-experimental before/after design– Group randomized controlled design

Inclusion / Exclusion -- Sites

• Inclusion:Access to an “asthma center”

(with some minimal criteria – eg, certified educator)

• Exclusion:Current asthma-related quality improvement initiative

(to avoid co-interventions during trial)

Inclusion / Exclusion -- Patients

• Inclusion:– Age 18-54– Treated in ED, with/without admission to hospital for

asthma treatment (excludes “direct” admissions)– Has sought urgent medical care for their asthma at

least one other time in past year

• Exclusion:– > 20 pack-year smoking history (to avoid COPD)– No telephone or unlikely to be available at 12 months

Measures

• Outcomes

• Patient baseline characteristics(including potential effect modifiers)

• Process measures

• Key mediators

Primary Outcome

Proportion of patients with 1 ED visit during one year follow-up period

Secondary Outcomes

• Proportion with 1 unscheduled clinic visit• Proportion with 1 hospitalization• Proportion with 1 ICS dispensed:

per Rx of ED or asthma center per Rx of PCP

• Proportion using an ICS routinely• Asthma symptoms• Asthma-related Quality of Life• Etc.

Baseline Characteristics – Sitecovariates & potential effect modifiers

• Characteristics of ED Setting Staffing Patient volume

• Characteristics of AC Years of operation as an AC Setting Staffing Qualifications of educator(s)

Baseline Characteristics – Patientcovariates & potential effect modifiers

• Demographic characteristics• Prior healthcare utilization for acute asthma• Medication adherence • Routine asthma care behavior• Environmental exposures• Self-management skills

(e.g., inhaler use, peak flow meter use)

• Prior asthma education

Measures of Intervention Process

1. Facilitated Referral by ED

Contact phone numbers obtained Asthma Center (AC) appointment

communicated within 48 hours Other assistance given, by type

(eg, language, insurance, other)

Intervention Process (cont.)

2. Asthma Center (AC) Management

AC visits to asthma specialist by patient Asthma education provided to patient

(eg, content, duration)

Social work services provided to patient

Intervention Process (cont.)

3. Communication Form:

Initiation by ED• Completeness (eg, contains services provided,

treatment plan)• Distribution (copied to patient, PCP, AC)

Use by AC• Completeness (eg, contains services provided,

treatment plan + patient outcomes)• Distribution (copied to patient and PCP)

Intervention Process (cont.)

ED, AC, and Patient perceptions of:

Data collection procedures (all sites)

Communication form (intervention sites only)

Plans to continue facilitated referral and use of form (intervention sites only)

Key Mediators

During follow-up period:

• ICS prescription

• Regular ICS use

Study Designs

1. Quasi-experimental before/after trial

2. Group randomized controlled trial

Design 1: Quasi-Experimental Before/After Trial

• Without pretest:NR XA O1 O2 O3

NR XB O1 O2 O3

 

• With pretest:NR O1 XA O2 O3 O4

NR O1 XB O2 O3 O4 XA = usual care

XB = intervention

Assignment of Patients

• Non-random assignment based on date of entry into study during one fall season

For example, at 1 site:Sept = control group (26 pts)

Oct = intervention group (26 pts) Both groups followed for 1 year

• All 40 sites provide usual care (516 patients) then intervention (516 patients)

Design 2: Group Randomized Controlled Trial

• Without pretest:R XA O1 O2 O3

R XB O1 O2 O3

 

• With pretest:R O1 XA O2 O3 O4

R O1 XB O2 O3 O4 XA = usual care

XB = intervention

RCT flow-chart

F o llo w -u p A sse ssm e nt(1 2 m o s .)

O u tco m e s , , P roce ss M e a su res

F o llo w -u p A sse ssm e nt(6 m o s .)

O u tco m es

Facilitated Referral& Asthm a Center Mgm t.

Pro ce ss M e asu re s

B a se line A ssessm e nt(P a tie n t C h ara c te ris t ic s)

E D P a tie n t R e cru itm e n tN = 5 1 6 (2 6 /E D )

In te rve n tionN = 20

F o llo w -u p A sse ssm e nt(1 2 m o s .)

O u tco m e s , , P roce ss M e a su res

F o llo w -u p A sse ssm e nt(6 m o s .)

O u tco m es

Usual Care

B a se line A ssessm e nt(P a tie n t C h ara c te ris t ic s)

E D P a tie n t R e cru itm e n tN = 5 1 6 (2 6 /E D )

U su a l C a reN = 20

EDs (N = 40)Random ize

Design Issues

• Many design issues are same for the two proposed studies

• For RCT, randomize EDs or patients?– Randomizing patients risks leakage of

intervention to controls(e.g., increased referral to asthma center or use of communication form)

– IRB or potential/actual participants may object to perceived “denial” of services

Design Issues (cont.)

• Recruit in peak season or entire year?– Peak season recruitment (Sept-Dec) more efficient

and less costly– Peak season recruitment requires ED, AC, and PCP

cooperation with intervention over shorter time

• Obtain patient-level pretest data on outcomes vs. site characteristics only?– Patient-level allows better statistical control for

pre-intervention site differences in outcomes– Incorporates a before-after component into RCT

RCT Flow-Chart: Pretest

EDs (N = 40)Random ize

F o llo w -u p A sse ssm e nt(1 2 m o s .)

(O u tco m e s )

B a se line A ssessm e nt(P a tie n t C h ara c te ris tic s)

E D P a tie n t R e cru itm e ntN = ? ? ? (? ? /E D )

EDs (N = 40)

Year prior to RCT

Trade-offs -- Advantages

Before-After• May objections to “denial”

of services• May post-study

intervention sustainability• More information on

variable implementation of intervention (40 vs 20 sites)

• Except for ramp-up at 40 sites (not 20), easier to perform study, less costly?

• Other advantages?

Group-RCT control for potential co-

interventions (eg, changes in asthma Tx, ED services)

control for seasonal patterns of asthma that could differentially affect two groups

i.e., internal validity

• Other advantages?