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Asthma Control Test (ACT) and cACT

Asthma Control Test (ACT) and cACT - Clinical Hub, UW Health Clinical Tool Search, UW Health Clinical Tool Search, Questionnaires, Related


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Key words: Asthma control assessment, Asthma Control Test
Approximately 20 million individuals in the United
States, 7.5% of the population, have asthma, and nearly
5000 Americans die from it each year.
1,2
The prevalence
of asthma and its personal and societal tolls continue to
increase despite advances in knowledge about the patho-
physiology of asthma and the availability of effective ther-
apy.
1-4
The National Asthma Education and Prevention
Program’s (NAEPP’s) 1997 ‘‘Expert panel report: guide-
lines for the diagnosis and management of asthma’’ and
the update in 2002 were intended to help improve the qual-
ity of care of asthma and to reduce asthma-associated dis-
ability, lost productivity, emergency health care use, and
Kline. R. A. Nathan has consultant arrangements with Amgen, Altana,
AstraZeneca, Aventis, Genentech, GlaxoSmithKline, Merck, Novartis,
Pfizer, Schering/Key, Sepracor, and Viropharm; has received grants–
research support from Abbot, Altana, Aventis, AstraZeneca, Bayer, Berlex,
Boehringer Ingelheim, Bristol-Myers Squibb, Ciba-Geigy, Dura, Forest,
GlaxoSmithKline, Immunex, Janssen, Parke-Davis, Pfizer, 3-M Pharma-
ceuticals, Proctor & Gamble, Roberts, Sandoz, Sanofi, Schering/Key,
Sepracor, Sterling, Tap Pharmaceuticals, Wallace, and Wyeth; and is on
the speakers’ bureau for AstraZeneca, Aventis, Genentech/Novartis, Glaxo-
SmithKline, Pfizer, and Schering/Key. M. Kosinski—none declared. T. B.
Pendergraft is employed by GlaxoSmithKline. P. Jhingran has stock or other
equity ownership in and is employed by GlaxoSmithKline.
Received for publication July 6, 2005; revised December 22, 2005; accepted
for publication January 4, 2006.
Reprint requests: Michael Schatz, MD, MS, Kaiser-Permanente Medical
Center, 7060 Clairemont Mesa Blvd, San Diego, CA 92111. E-mail:
Michael.x.schatz@kp.org.
0091-6749/$32.00
� 2006 American Academy of Allergy, Asthma and Immunology
doi:10.1016/j.jaci.2006.01.011
Original articles
Asthma Control Test:
and responsiveness in
followed by asthma s
Michael Schatz, MD, MS,
a
Christine A. Sor
Philip Marcus, MD, MPH,
d
John J. Murray,
Kosinski, MA,
g
Trudy B. Pendergraft, MSP
Madison, Wis, Rochester, Minn, Great Neck, NY,
RI, and Research Triangle Park, NC
Background: The development of the Asthma Control Test
(ACT), a short, simple, patient-based tool for identifying
patients with poorly controlled asthma, was recently described
in patients under the routine care of an asthma specialist.
Objectives: We sought to evaluate the reliability and validity
of the ACT in a longitudinal study of asthmatic patients new
to the care of an asthma specialist.
From
a
Kaiser-Permanente Medical Center, San Diego;
b
the University of
Wisconsin School of Pharmacy, Madison;
c
Mayo Medical Center, Roches-
ter;
d
Nassau Chest Physicians, PC, Great Neck;
e
the Vanderbilt Asthma
Sinus Allergy Program, Nashville;
f
Asthma and Allergy Associates and
Research Center, Colorado Springs;
g
QualityMetric, Incorporated, Lincoln;
and
h
GlaxoSmithKline, Research Triangle Park.
The research described in this article was funded by GlaxoSmithKline.
Disclosure of potential conflict of interest: M. Schatz has received grants–
research support from GlaxoSmithKline and Sanofi-Aventis and is on the
speakers’ bureau for AstraZeneca and Merck. C. A. Sorkness has consultant
arrangements with GlaxoSmithKline and AstraZeneca, has received grants–
research support from GlaxoSmithKline, and is on the speakers’ bureau
for GlaxoSmithKline and Genentech. J. T. Li has had consultant arrange-
ments with GlaxoSmithKline and has received grants–research support
from GlaxoSmithKline. P. Marcus has consultant arrangements with
Altana, has received grants–research support from GlaxoSmithKline and
AstraZeneca, and is on the speakers’ bureau for GlaxoSmithKline,
Genentech, Novarits, Merck, and Aventis. J. J. Murray has consultant
arrangements with GlaxoSmithKline, has received grants–research support
from GlaxoSmithKline, and is on the speakers’ bureau for GlaxoSmith-
Reliability, validity,
patients not previously
pecialists
kness, PharmD,
b
James T. Li, MD, PhD,
c
MD, PhD,
e
Robert A. Nathan, MD,
f
Mark
H,
h
and Priti Jhingran, PhD
h
San Diego, Calif,
Nashville, Tenn, Colorado Springs, Colo, Lincoln,
Methods: Patients (n 5 313) completed the ACT and the
Asthma Control Questionnaire (ACQ) at 2 physician visits
(4-12 weeks apart). Pulmonary function was measured, and
asthma specialists rated asthma control.
Results: Internal consistency reliability of the ACT was 0.85
(baseline) and 0.79 (follow-up). Test-retest reliability was 0.77.
Criterion validity was demonstrated by significant correlations
between baseline ACT scores and baseline specialists’ ratings of
asthma control (r 5 0.52, P < .001) and ACQ scores (r 520.89,
P < .001). Discriminant validity was demonstrated, with
significant (P < .001) differences in mean ACT scores across
patients differing in asthma control, pulmonary function, and
treatment recommendation. Responsiveness of the ACT to
changes in asthma control and lung function was demonstrated
with significant correlations between changes in ACT scores
and changes in specialists’ ratings (r 5 0.44, P < .001), ACQ
scores (r 520.69, P < .001), and percent predicted FEV
1
values
(r 5 0.29, P < .001). An ACT score of 19 or less provided
optimum balance of sensitivity (71%) and specificity (71%)
for detecting uncontrolled asthma.
Conclusions: The ACT is reliable, valid, and responsive to
changes in asthma control over time in patients new to the care
of asthma specialists. A cutoff score of 19 or less identifies
patients with poorly controlled asthma.
Clinical implications: In a clinical setting the ACT should
be a useful tool to help physicians identify patients with
uncontrolled asthma and facilitate their ability to follow
patients’ progress with treatment. (J Allergy Clin Immunol
2006;117:549-56.)
549

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Abbreviations used
ACQ: Asthma Control Questionnaire
ACT: Asthma Control Test
NAEPP: National Asthma Education and Prevention
Program
ROC: Receiver operating characteristic
death.
5,6
These guidelines are broadly endorsed and were
widely disseminated among health care providers.
However, studies show that although several years have
passed since the guidelines were issued, they have not
been effectively implemented in many health care set-
tings.
7-11
Furthermore, the NAEPP-defined goals of asthma
care (ie, prevention of symptoms and exacerbations; main-
tenance of normal pulmonary function and activity levels;
provision of well-tolerated, effective pharmacotherapy;
minimization of the need for emergency department visits
or hospitalizations; and achieving patients’ expectations
of asthma care) have not been met for a substantial pro-
portion of patients with asthma.
12-14
Two nationally repre-
sentative US surveys conducted after publication of the
guidelines suggest that poor asthma control remains perva-
sive.
2,13
In a recent survey based on the 2002 Behavioral
Risk Factor Surveillance System, more than 30% of patients
reported an urgent visit to their physician for asthma in the
prior year, more than 30% reported activity limitation
caused by asthma in the prior year, and more than 50%
reported sleep disturbance caused by asthma in the prior
month.
2
Asthma control is important to assess in clinical prac-
tice, although it is multidimensional in nature, character-
ized by symptoms, changes in pulmonary function, and
effects on quality of life and functional ability.
14
Measures
of pulmonary function, symptoms, and quality of life often
correlate poorly with one another and appear to provide
independent information about clinical status, with lung
function providing a point-in-time assessment and with
questionnaires assessing status over a given time pe-
riod.
15-18
Assessing any one of these aspects alone does
not accurately gauge asthma control, but routine assess-
ment of all of these aspects individually is usually not fea-
sible given constraints on time and resources in the clinical
setting. In particular, spirometry is often not available in
the primary care setting.
Tools that reflect the multidimensional nature of asthma
control and that are easily and quickly administered and
interpreted are needed to facilitate the assessment of
asthma control in a busy clinical practice. The Asthma
Control Test (ACT), a 5-item, patient-administered survey
for assessing asthma control (Fig 1), was developed to
meet this need. In a previous study the development of
the ACT was documented in a sample of asthmatic pa-
tients under the routine care of an asthma specialist.
19
Results indicated that the ACT is a clinically valid mea-
sure that can be useful to clinicians and should be evalu-
ated in assessing asthma control in different patient
550 Schatz et al
populations. The study reported herein was conducted to
evaluate the reliability and validity of the ACT survey
and to assess its responsiveness to changes in asthma con-
trol over time in a sample of patients new to the care of
an asthma specialist. It was thought that this sample of
patients might be more likely than those being followed
by specialists to have poorly controlled asthma and to be
more representative of the patient population in which
the ACT survey might be most useful; that is, among those
for whom little or no historical data are available to assist
the physician in assessing the current level of asthma
control.
METHODS
ACT survey
The ACT survey is a patient-completed questionnaire with 5 items
assessing asthma symptoms (daytime and nocturnal), use of rescue
medications, and the effect of asthma on daily functioning (Fig 1).
Each item includes 5 response options corresponding to a 5-point
Likert-type rating scale. In scoring the ACT survey, responses for
each of the 5 items are summed to yield a score ranging from 5
(poor control of asthma) to 25 (complete control of asthma).
Details of the development of the ACT are reported elsewhere.
19
Data collection
Patients. Patients were recruited through local media advertising
of the study or by virtue of their consulting one of the participating
asthma specialty practices for the first time. Patients 12 years of age or
older were eligible if they had not consulted an asthma specialist
within 5 years before the study, had a physician diagnosis of asthma
without respiratory comorbidities, were literate in English, and were
not participating in other clinical studies at the time of enrollment. All
patients, their parents or guardians, or both provided written informed
consent.
Procedures. The protocol for this study was approved by insti-
tutional review boards for each of the 6 participating asthma specialist
practices. At 2 scheduled physician office visits separated by 4 to 12
weeks (the baseline visit and the follow-up visit), patients completed
(1) the ACT survey; (2) the Asthma Control Questionnaire (ACQ),
20
a previously validated tool for measurement of asthma control (6-item
version without pulmonary function); and (3) prebronchodilator mea-
surements of FEV
1
. Asthma specialists blinded to ACT and ACQ sur-
vey responses rated asthma control on a 5-point scale ranging from
‘‘not controlled at all’’ to ‘‘completely controlled.’’ The specialists
were instructed to base their ratings on how well the NAEPP-defined
goals of asthma were being met, as determined on the basis of infor-
mation from the patient history, physical examination, and FEV
1
measurement.
Assessments
Reliability. The reliability of ACT scores was assessed by using
internal consistency and test-retest methods. For internal consistency
reliability, the Cronbach a value was estimated from ACT item
responses at baseline and follow-up visits. Test-retest reliability was
assessed by computing the intraclass correlation between ACT scores
at the baseline and follow-up visits. The test-retest reliability analysis
was limited to a subset of patients whose asthma control was stable, as
determined by the same specialist ratings of asthma control at both
baseline and follow-up visits.
Criterion validity. Criterion validity of the ACT survey was
evaluated by computing correlations between ACT scores at the
baseline visit and (1) the specialist assessment of asthma control and
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Schatz et al 551
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(2) scores on the ACQ.
20
Correlations were also computed between
baseline ACT scores and percent predicted FEV
1
values.
Discriminant validity. The discriminant validity of the ACT was
also evaluated in clinical tests by using the methods of known-groups
validity
21
and data from the baseline visit. The method of known-
groups validity compares mean ACT scores across groups of patients
known to differ on a relevant clinical measure. In this study 3 such
measures were used. The first was the asthma specialist’s rating of
asthma control, which consisted of 5 categories: (1) not controlled
at all; (2) poorly controlled; (3) somewhat controlled; (4) well con-
trolled; and (5) completely controlled. The second measure consisted
of percent predicted FEV
1
values. Patients were categorized into 4
groups on the basis of their percent predicted FEV
1
values: (1) less
than 60%; (2) 60% to 79%; (3) 80% to 100%; and (4) greater than
100%. This stratification of percent predicted FEV
1
values was
roughly based on the NAEPP breakdown of asthma severity (mild
intermittent and mild, moderate, and severe persistent asthma).
5,6
The third measure consisted of the asthma specialist’s treatment rec-
ommendation, which was used to categorize patients into 3 groups:
(1) step up in therapy; (2) no change in therapy; and (3) step down in
therapy. For each of the above measures, mean ACT scores were
computed and compared across patient groups. One-way ANOVA
methods were used to test the significance of differences in mean
ACT scores across groups of patients who differed in specialist rat-
ings of asthma control, percent predicted FEV
1
values, and treatment
recommendation. It was hypothesized that ACT scores would be
higher (indicating better control) among groups of patients with better
asthma control reflected in specialist ratings and percent predicted
FEV
1
values compared with scores in patients with poorer control.
Similarly, ACT scores were expected to be higher among the group
of patients in whom a step down in therapy was recommended com-
pared with the group of patients for whom a step up in therapy was
recommended.
Screening accuracy. The accuracy of the ACT as a tool for
screening patients with asthma control problems was assessed with
logistic regression methods and receiver operating characteristic
(ROC) curve analyses by using baseline data. The criterion measure
for these analyses was the specialist’s rating of asthma control. In the
primary evaluation patients were categorized as having uncontrolled
asthma if the specialist rating was ‘‘somewhat controlled,’’ ‘‘poorly
controlled,’’ or ‘‘not controlled at all.’’ Patients were categorized
as having controlled asthma if the specialist rating was ‘‘well
controlled’’ or ‘‘completely controlled.’’ A separate analysis was
conducted for every possible cut-point score from 10 to 24 on the
ACT. Results were summarized in terms of sensitivity, specificity,
percentage of patients correctly classified, positive and negative
FIG 1. Asthma Control Test.

J ALLERGY CLIN IMMUNOL
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552 Schatz et al
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predictive values, and area under the ROC curve. In a secondary
evaluation to determine the lower cutoff point for somewhat
controlled asthma, the above methods were used, but patients with
somewhat controlled asthma were considered to be controlled, and
patients with well-controlled or completely controlled asthma were
excluded.
Responsiveness. The responsiveness of ACT scores was evaluated
with correlations and ANOVA methods. First, changes in ACT scores
from baseline to the follow-up visit were correlated with changes in
the specialist’s rating of asthma control, changes in lung function as
measured by the change in FEV
1
values, and changes in ACQ scores.
Second, ANOVA was used to compare mean changes in ACT scores
across groups of patients who differed in the level of change in the
specialist’s rating of asthma control, change in percent predicted
FEV
1
values, and change in ACQ scores. The patient groups for
each of these criterion measures were derived as follows:
1. Specialist control rating: Change in specialist control rating was
derived by simply subtracting the baseline rating from the follow-
up rating. Because few patients got worse on the specialist control
rating over time, it was necessary to collapse the categories of
change indicative of worsening into one category. Patients were
grouped into 4 categories of change in control ratings: (1) worse
rating by 1 or more levels; (2) same rating; (3) improved rating
by 1 level; and (4) improved rating by 2 levels.
2. Percent predicted FEV
1
values: Change in percent predicted
FEV
1
values was derived by subtracting the baseline percent pre-
dicted FEV
1
values from the follow-up percent predicted FEV
1
values and dividing by the baseline percent predicted FEV
1
value to produce an indicator of the percentage of improvement
in percent predicted FEV
1
values. Patients were categorized into
2 groups according to the working group’s recommended thresh-
old for clinical meaningful improvement in percent predicted
FEV
1
values. The first group consisted of patients who improved
by 10% or more from baseline. The second group consisted of
patients who did not improve by 10% or more from baseline.
3. ACQ scores: Change scores were computed by subtracting the
baseline ACQ score from the follow-up ACQ score. Patients
were categorized into 3 groups according to the magnitude of
their ACQ score change. By using the minimal important differ-
ence established for the ACQ,
22
patients were categorized as bet-
ter if their improvement in ACQ score was equal to or better than
TABLE I. Sample characteristics
Baseline visit
(n 5 313)*
Follow-up visit
(n 5 250)*
Mean age, y (SD) 35.3 (15.3) 35.8 (15.0)
Specialist control rating, n (%)
Not controlled at all 12 (3.9) 0 (0.0)
Poorly controlled 60 (19.4) 13 (5.2)
Somewhat controlled 88 (28.5) 65 (26.1)
Well controlled 121 (39.2) 133 (53.4)
Completely controlled 28 (9.0) 38 (15.3)
Mean % predicted FEV
1
(SD) 89.0 (20.7) 91.2 (15.7)
% Predicted FEV
1
categories,
n (%)
<60% 22 (7.1) 9 (3.6)
60% to 79% 64 (20.7) 47 (18.9)
80% to 100% 140 (45.3) 127 (51.0)
>100% 83 (26.9) 66 (26.5)
*The frequencies might not add up to the total sample size because of
missing data.
0.5. Patients were categorized as worse if the decrease in ACQ
score was equal to or worse than 0.5. Lastly, patients were cat-
egorized as the same if the change in ACQ score was between
20.5 and 10.5.
It was hypothesized that ACT scores would improve on average
among patient groups whose asthma control improved, as defined
by changes in the specialists’ ratings of control, percent predicted
FEV
1
values, and ACQ scores.
RESULTS
Sample
The number of patients participating in the study was
313. The mean age of the patients was 35 years (SD, 15.3),
with a range of 12 to 84 years. At the baseline visit,
specialists rated asthma control as well controlled or
completely controlled in 48% of the 301 patients for
whom data were available, somewhat controlled in 29% of
the patients, and poorly controlled or not controlled at all
in 23% of patients. The mean percent predicted FEV
1
value at the baseline visit for the 301 patients for whom
data were available was less than 60% for 7.6% of patients,
60% to 79% for 20.6% of patients, 80% to 100% for
44.2% of patients, and more than 100% for 27.5% of
patients (Table I).
Reliability
The internal consistency reliability of the ACT survey
was 0.85 at the baseline visit (n 5 313) and 0.79 at the
follow-up visit (n 5 248). The test-retest reliability among
the 86 patients with the same specialist rating of asthma
control at the baseline and follow-up visits was 0.77.
Criterion validity
Statistically significant correlations were observed
between ACT scores at the baseline visit and baseline
values for the specialist rating of asthma control (r 5 0.52,
TABLE II. Discriminant validity tests on mean ACT scores
at baseline (n 5 301)
Mean (SD)
ACT score F statistic
Specialist assessment
Not controlled at all (n 5 11) 13.3 (4.7) 27.5*
Poorly controlled (n 5 59) 14.5 (4.8)
Somewhat controlled (n 5 87) 17.4 (4.7)
Well controlled (n 5 166) 20.3 (3.4)
Completely controlled (n 5 28) 21.5 (3.9)
Percent predicted FEV
1
<60% (n 5 23) 14.4 (4.7) 16.1*
60% to 79% (n 5 62) 15.7 (4.8)
80% to 100% (n 5 133) 19.2 (4.6)
>100% (n 5 83) 19.5 (4.1)
Therapy recommendation
Stepped down (n 5 13) 17.9 (5.6) 32.9*
No change (n 5 141) 20.4 (3.6)
Stepped up (n 5 147) 16.1 (5.0)
*P<.001.

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Schatz et al 553
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significantly lower than patients with no change in therapy
or with stepped-down therapy (F 5 32.9, P<.001).
Accuracy in screening for poorly
controlled asthma
Table III summarizes the performance of the ACT in
screening for asthma control problems across various
cut-point scores. Classification statistics are presented
for each cut-point score on the ACT, beginning with a
score of 10. Score levels of less than 10 are not presented
because of poor classification statistics. As shown in Table
III, lower cut-point scores on the ACT yielded lower sen-
sitivity and higher specificity statistics and high positive
predictive values (fewer false-positive results). Higher
cut-point scores on the ACT yielded higher sensitivity
and lower specificity statistics and relatively lower posi-
tive predictive values (higher false-positive rate). The
highest area under the ROC curve was observed for a
cut-point score of 19, at which the sensitivity and specific-
ity of the ACT was 71.3% and 70.8% and the positive and
negative predictive values were 72.6% and 69.3%,
tions between changes in ACT scores and changes in
specialist control ratings, percent predicted FEV
1
values,
and ACQ scores. As shown, changes in ACT scores
were moderately correlated with changes in specialist con-
trol ratings (r 5 0.44, P<.001) and highly correlated with
changes in ACQ scores (r 520.81, P<.001). The corre-
lation between changes in ACT scores and percent pre-
dicted FEV
1
values was considerably lower (r 5 0.29,
P<.001).
The responsiveness of the ACT was also demonstrated
by evaluating mean changes in ACT scores across groups
of patients differing in the level of change in the special-
ist’s rating of asthma control, change in percent predicted
FEV
1
values, and minimally important changes in ACQ
scores (Table V). Mean score changes on the ACT differed
significantly across the groups of patients differing in the
level of change on the specialist control rating (F 5 24.2,
P<.001), percent predicted FEV
1
value (F 5 32.9,
P<.001), and ACQ score (F 5 71.0, P<.001). As hy-
pothesized, ACT scores improved among patient groups
whose asthma control improved, as defined by changes
P<.001) and ACQ scores (r 520.89, P<.001). Baseline
ACT scores also correlated significantly with baseline per-
cent predicted FEV
1
values (r 5 0.31, P<.001).
Discriminant validity
Significant differences in mean scores across groups of
patients who differed on each clinical measure related to
asthma control according to hypotheses lend support to the
discriminant validity of ACT scores (Table II). Mean ACT
scores were significantly lower among patients with
poorer control as judged by the specialist than among
patients with more favorable control ratings (F 5 27.5,
P<.001). Likewise, patients with poorer lung function
(percent predicted FEV
1
) scored significantly lower on
the ACT than patients with better lung function (F 5
16.1, P<.001). Finally, patients whose therapy was step-
ped up as a result of the visit with the specialist scored
TABLE III. Performance of the ACT survey at various cut poin
Cut-point
score Sensitivity (%) Specificity (%)
Positive predic
value (%)
�10 17.5 98.6 93.3
�11 22.5 98.6 94.7
�12 25.6 97.9 93.2
�13 28.8 95.9 88.5
�14 35.0 93.9 86.2
�15 41.9 90.5 82.7
�16 50.0 87.1 80.8
�17 58.8 80.9 77.1
�18 62.5 74.8 73.0
�19 71.3 70.8 72.6
�20 78.8 57.1 66.7
�21 88.1 45.6 63.8
�22 92.5 32.0 59.7
�23 96.3 19.1 56.4
�24 98.8 12.9 55.2
*Categorized by asthma specialist as somewhat controlled, poorly controlled, or
respectively, and the percentage of patients correctly clas-
sified was 71%. By using this cut point, of patients with
controlled asthma on the basis of ACT score (>19), only
8% were deemed by the specialist to have their symptoms
not controlled or poorly controlled. In contrast, of patients
with uncontrolled asthma on the basis of ACT score
(�19), 27% were rated by the specialist as having their
symptoms well controlled or completely controlled.
Table IV shows the evaluation of a cutoff for somewhat
controlled asthma versus asthma that is poorly controlled
or not controlled at all. The table shows that a cut point of
�15 yields the highest percentage of patients correctly
classified and the highest area under the ROC curve.
Responsiveness
Evidence of the responsiveness of ACT scores to
changes in asthma control was demonstrated in correla-
ts in screening for uncontrolled asthma*
tive Negative predictive
value (%)
Percent correctly
classified
Area under
ROC curve
52.4 56.4 0.581
53.9 58.9 0.606
54.8 60.3 0.618
55.3 60.9 0.623
57.0 63.2 0.644
58.9 65.2 0.662
61.5 67.8 0.685
64.3 69.4 0.698
64.7 68.4 0.687
69.3 71.0 0.710
71.2 68.4 0.679
77.9 67.8 0.669
79.7 63.5 0.622
82.3 59.3 0.577
90.5 57.7 0.558
not controlled at all.

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in the specialists’ ratings of control, percent predicted
FEV
1
values, and ACQ scores.
DISCUSSION
A cornerstone of the NAEPP guidelines for managing
asthma is the ongoing assessment of asthma control,
which is crucial for optimizing care and reducing the
humanistic, economic, and societal burdens of the disease.
Data suggest that patients with asthma and their physicians
often overestimate the degree to which asthma is con-
trolled.
12
Overestimation of asthma control can result in
failure to use needed interventions or to make necessary
adjustments to medication regimens; the lack of interces-
sion in turn can result in worsening asthma-associated
pendent cross-validation of the results observed in the de-
velopmental study of the ACT in a sample of patients with
asthma who had not consulted an asthma specialist for at
least 5 years before enrollment in the study. This pop-
ulation might be more representative of patients seen in
the primary care setting than the sample of patients who
participated in the development study of the ACT. In
addition, the current study extends previous findings by
providing evidence of the responsiveness of ACT scores
to changes in asthma control over time.
The ACT survey performed well compared with 2
criterion measures, specialists’ ratings of asthma control
and ACQ scores, in defining the level of asthma control
and the need for adjustment of therapy and in detecting
changes in asthma control over time. Because the special-
ists’ ratings of asthma control were based on comparison
of the patients’ status with NAEPP-defined goals of
asthma care,
5,6
these findings suggest that the ACT survey
can help to gauge the degree to which NAEPP goals are
being met. There is no gold standard for asthma control
measurement. In lieu of a universal gold standard, we be-
lieved that the best approach was to use as our gold stan-
dard the summary judgment of experienced specialists
ACQ score
Better (n 5 93) 3.94 (3.4) 71.0*
Same (n 5 129) 0.39 (1.6)
Worse (n 5 24) 21.08 (2.2)
*P<.001.
TABLE IV. Summary of the performance of the ACT at vario
versus somewhat controlled asthma
Cut-point score Sensitivity (%) Specificity (%)
Positive p
value
�10 23.6 87.5 60.
�11 30.6 84.1 61.
�12 36.1 82.9 63.
�13 43.1 82.9 67.
�14 50.0 77.3 64.
�15 61.1 73.9 65.
�16 69.4 65.9 62.
�17 77.8 56.8 59.
�18 79.2 51.1 57.
�19 83.3 38.6 52.
�20 87.5 28.4 50.
�21 – – –
�22 – – –
�23 – – –
�24 – – –
Continuous score 50.0 77.3 64.
*Uncontrolled asthma defined by physician global assessment (not controlled p
TABLE V. Mean changes in ACT scores as a function of
changes in specialists’ ratings of asthma control and
changes in FEV
1
values and ACQ scores
Mean (SD) change
in ACT score F statistic
Specialist assessment
Worse (n 5 44) 20.02 (1.7) 24.2*
Same (n 5 85) 0.73 (2.2)
Better by 1 rating level (n 5 80) 1.88 (3.1)
Better by 2 rating levels (n 5 37) 4.8 (3.9)
FEV
1
<10% improvement (n 5 212) 1.17 (2.8) 32.9*
�10% improvement (n 5 34) 4.32 (4.0)
disability that in some cases can culminate in death.
Improving the ability to assess asthma control is impera-
tive but has proved difficult. The results of this study dem-
onstrate that the ACT, developed to facilitate rapid and
accurate assessment of asthma control, is reliable, valid,
and responsive to changes in asthma control over time
in a sample of patients new to the care of an asthma
specialist.
The results of this study corroborate those of the
developmental study of the ACT survey in which the
ACT scores were shown to be reliable and valid in
assessing asthma control in patients under the care of
asthma specialists.
19
The current study represents an inde-
us cut points in screening for uncontrolled asthma*
redictive
(%)
Negative predictive
value (%)
Percent correctly
classified
Area under
ROC curve
7 58.3 58.8 0.5556
1 59.7 60.0 0.5732
4 61.3 61.9 0.5953
4 64.0 65.0 0.6301
3 65.4 65.0 0.6364
7 70.0 68.2 0.6768
5 72.5 67.5 0.6749
6 75.8 66.3 0.6730
0 75.0 63.8 0.6515
6 73.9 58.8 0.6098
0 73.5 55.0 0.5795
– – –
– – –
– – –
– – –
3 65.4 65.0 0.6892
lus poorly controlled, n 5 72) versus somewhat controlled (n 5 88).

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who were aware of both the National Heart, Lung, and
Blood Institute goals of therapy, as well as all relevant
aspects of their patient’s clinical status.
The correlations between ACT scores and FEV
1
values
were substantially lower than the correlations between
ACT scores and the above criterion measures. This obser-
vation is consistent with the findings from other studies
that suggest that asthma control cannot be inferred from
single measures of lung function.
16,20
The prior observa-
tion
19
that ACT scores correlate better with specialist
global assessments of asthma control than do FEV
1
measurements confirms that specialists’ assessments of
asthma control are based on more than just lung function
measurements.
Assessments of the ACT’s screening accuracy for
poorly controlled asthma suggest that patients with an
ACT score of 19 or less might be experiencing control
problems. This score provided the optimum balance of
sensitivity (71%) and specificity (71%) for detecting
patients with uncontrolled asthma (Table II). A cut-point
score of 19 also yielded the largest area under the ROC
curve, which replicates the findings from the developmen-
tal study.
19
A score of 19 or less on the ACT might signal
the need for further evaluation of the patient to determine
whether adjustments to asthma treatment regimens or
other measures are required to improve asthma control.
Depending on the specific objectives of the user, other
cut points could be considered for screening poorly con-
trolled asthma. In general, the higher the ACT scores on
the range of 5 to 25, the better the control. For example,
if it is important to maximize specificity (fewer false-
positive results), then cut-point scores of less than 19
might be appropriate. However, if the intent is to improve
asthma symptoms, maintain asthma symptoms, or both
at a minimum well-controlled level and with the goal of
achieving complete asthma control, then cut-point scores
of 20 or more are appropriate with the goal of reaching
an ideal score of 25. Our data also suggest that scores of
15 or less are particularly of concern because they predict
asthma that is poorly controlled or not controlled at all.
Increasingly, physicians are seeing a higher volume of
patients within the same limited time. Given the limited
physician-patient interaction time, an accurate, reliable,
and easy-to-use control tool might be essential in the
management of asthmatic patients. The ACT was specif-
ically designed for use in physician practices. Therefore it
provides a more simplified assessment of control by not
requiring FEV
1
values, which might not always be avail-
able, and by providing a meaningful and easy-to-use scor-
ing method, which is simpler than the ACQ and yet more
comprehensive than the Asthma Therapy Assessment
Questionnaire for evaluating the range of asthma control.
Besides being useful as a screener for uncontrolled
asthma, the ACT survey is suitable for periodic monitor-
ing of patients with asthma, as demonstrated by the finding
that ACT scores were responsive to changes in asthma
control over time. In this study ACT scores were respon-
sive to changes in asthma control, as determined by
changes in specialist ratings, lung function, and ACQ
VOLUME 117, NUMBER 3
scores. Repeatedly administered to the individual patient
over time, the ACT survey might be useful in gauging
the success of therapeutic interventions and in identifying
deterioration in asthma control and therefore could be
considered a useful tool in clinical research, as well as in
clinical practice.
In conclusion, the results of this longitudinal validation
study show that the ACT is reliable, valid, and responsive
to changes in asthma control over time in patients naive to
asthma specialty care. The ACT is an easily administered
and scored survey that measures asthma control accurately
compared with specialist ratings on the basis of history,
physical examination, and lung function tests and with
the previously validated ACQ. The ACT survey should
facilitate efforts to improve assessment of asthma control
in the busy clinical practice setting.
We thank Sidney S. Braman, MD, Brown University School
of Medicine; Douglas C. Cline, MD, Broadway Family Practice
& Trenton Family Practice; Matthew L. Mintz, MD, George
Washington University Medical Center; Russel J. T. Perry, MD,
New York Medical College; and Maureen George, MSN, RN, CS,
University of Pennsylvania Health System, for their participation
as part of the working group. We would also like to thank
Jacqueline Carranza Rosenzweig, PharmD, MS; Laura Sutton,
PharmD; Bill Lincort, BS; Sharon Srebro, MD; and Richard
Stanford, PharmD, MS, GlaxoSmithKline, for their input, comments,
and discussions.
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