Validation of a Disease-Specific Measure of Health-Related Quality of
Life for Children with Cystic Fibrosis
Avani C. Modi,1 MS, and Alexandra L. Quittner,2 PHD
1
Department of Clinical and Health Psychology, University of Florida, and 2Department of
Psychology, University of Miami
Objective The purpose of the current study was to evaluate the psychometric properties
of the Cystic Fibrosis Questionnaire (CFQ)–Child version, a disease-specific health-related
quality of life (HRQOL) measure for children with cystic fibrosis (CF). Method The CFQ
was administered to 84 children with CF, ranging in age from 7 to 13 years, and their parents.
Results Multitrait analyses indicated that a majority of items on the CFQ-Child correlated
more highly with their hypothesized scale than a competing scale. Internal consistency coefficients were acceptable for all scales (Cronbach’s α = .60 –.76), with the exception of treatment burden (Cronbach’s α = .44). Results also suggested strong convergence between child
and parent-proxy reports on several scales of the CFQ. Conclusion Results demonstrated
that the CFQ-Child is a reliable and valid measure of HRQOL for children with CF.
Key words health-related quality of life; children; Cystic Fibrosis; validation.
Cystic fibrosis (CF) is the most common fatal, autosomal
recessive disorder of Caucasian populations. The incidence is 1 in 3,400 live births in the United States
(Kosorok, Wei, & Farrell, 1996), and it is estimated that
approximately 10 million individuals are carriers of the
recessive gene worldwide (Cystic Fibrosis Foundation
[CFF], 2002). CF is a complex, progressive disease that affects the exocrine glands of major organs, including those
of the respiratory, digestive, pancreas, liver, kidney, and
reproductive systems. Treatment of the disease involves
a multicomponent regimen, including airway clearance
techniques, aerosol medications, inhalers, pancreatic enzymes, increased calorie intake, and antibiotics (Orenstein, Rosenstein, & Stern, 2000). These treatments are
complex and time-consuming and must be performed several times each day (Quittner, Opipari, Regoli, Jacobsen, &
Eigen, 1992).
Life expectancy for individuals with CF has increased
dramatically in the last few decades. Twenty years ago,
individuals with CF survived into adolescence, but today
earlier diagnosis and more aggressive treatments have ex-
tended life expectancy into adulthood. Currently, the median life span for individuals with CF is approximately
33 years (CFF, 2002). However, it is estimated that the
median life expectancy for children born in 1990 is approximately 40 years. Although life span has increased
substantially, the “quality” of these additional years has
not been assessed.
The measurement of health-related quality of life
(HRQOL) has received considerable attention over the
past 20 years. Although early on there was no consensus
about the definition of the construct (Aaronson, 1992),
significant progress has been made recently in defining
and measuring HRQOL. Over 50 years ago, the World
Health Organization (WHO, 1947) defined health as “a
state of complete physical and social well being, not just
the absence of the disease.” This definition identified key
dimensions of health that should be included, such as
physical, social, and psychological domains. Identification of these domains expanded the construct of HRQOL
and led to a set of principles which guided its measurement
(Spieth & Harris, 1996). A widely accepted definition of
All correspondence concerning this article should be addressed to Avani Modi, Department of Clinical and Health
Psychology, University of Florida, 101 South Newell Dr. (Rm. 3151), PO Box 100165, Gainesville, Florida 32610.
E-mail: [email protected].
Journal of Pediatric Psychology, Vol.  No. , , pp. – ©  Society of Pediatric Psychology
DOI: 10.1093/jpepsy/jsg044

Modi and Quittner
HRQOL specifies that it (a) is a multidimensional construct that includes the core dimensions of physical functioning and symptoms, psychological functioning, occupational functioning, and social functioning (Schipper,
Clinch, & Olweny, 1996); (b) is patient centered rather
than reliant on the physician’s view; and (c) reflects the individual’s subjective evaluation of his/her own functioning
and well-being (Quittner, 1998). The purpose of the current study was to evaluate the psychometric properties of
a new, disease-specific measure of HRQOL for children
with CF.
Why is it important to measure HRQOL in patients
with CF? First, HRQOL measures have the potential to
describe health status in a meaningful way to health care
professionals and patients and their families (Abbott,
Webb, & Dodd, 1997). A traditional health outcome measure, such as pulmonary functioning, which is the primary biological indicator of health status in patients with
CF, uses a single number to assess health. Pulmonary functioning measures provide an estimate of current lung function, which may not correspond to the patient’s perception
of illness severity. In contrast, HRQOL measures provide
a more comprehensive assessment of how this disease affects patients’ daily lives in several areas of functioning, including physical, emotional, and social. Thus, HRQOL
measures may be used to complement existing clinical
measures and provide health care professionals with a
more thorough assessment of functioning (Abbott et al.,
1997).
Second, HRQOL measures are useful for evaluating
the impact of new treatments on individuals with CF. With
the advent of new medications and treatments, measures
of HRQOL enable us to assess the effectiveness of these
treatments in several areas of functioning. New drug therapies, such as recombinant human deoxyribonuclease
(rhDNase) and inhaled antibiotics, have been evaluated
in safety and efficacy trials and have demonstrated modest improvements in pulmonary function and improved
perception of HRQOL (Fuchs et al., 1994; Ramsey et al.,
1993). Similarly, in a recent study examining the effects on
HRQOL of a tobramycin solution for inhalation, researchers found that patients or parents of children with
CF in the treatment arm reported higher HRQOL on a
global rating question compared with control patients
(Quittner & Buu, 2002). Although the results of these
studies are promising, the use of ad hoc questions, rather
than standardized, well-validated HRQOL measurements,
limits our understanding of the impact of these treatments
on other important areas of functioning (e.g., social, emotional, vitality).
Third, measurement of HRQOL may have an impact
on adherence to complex medical regimens (Quittner,
1998). Individuals with CF are prescribed several timeconsuming treatments, which must be performed each
day in order to prevent lung infections and irreversible
lung damage. Several studies have indicated that rates of
adherence are generally low (Anthony, Paxton, Bines, &
Phelan, 1999; Passero, Remor, & Salomon, 1981; Quittner, Drotar, et al., 2000), leading to a variety of negative
health consequences, such as increased hospitalizations,
emergence of resistant bacteria and viruses, missed days at
school and work, and higher health care costs. If patients
perceive that a medication is effective and improves their
daily functioning, they are more likely to adhere to the
regimen (Bernstein, Kleinman, Barker, Revicki, & Green,
2002). In conjunction with other health outcome data,
HRQOL measures can provide individuals with information about how prescribed treatments are positively affecting various aspects of their lives (Quittner, Davis, &
Modi, 2003).
Finally, HRQOL data can inform economic planning
and decision making (Kaplan, 1989; Torrance, 1987).
Many of the drug and airway clearance therapies for CF,
such as rhDNase and the ThAIRapy(r) Vest (Advanced
Respiratory, St. Paul, Minnesota), are quite expensive,
ranging from $17,000 to $20,000. These treatments should
be evaluated for their efficacy in terms of their impact on
a broad range of outcomes, including physical, psychological, and social. This information is critical in deciding
how to distribute and spend health care dollars associated with complex, chronic illnesses such as CF (Kaplan,
1989).
Measurement of HRQOL in Children with
Cystic Fibrosis
One significant limitation of current HRQOL research is
the lack of measures for children and adolescents (Landgraf, Abetz, & Ware, 1996; Varni, Seid, & Rode, 1999).
HRQOL measures designed for children should be developmentally appropriate and assess daily functioning in
contexts that are relevant for children, such as school and
community. Prior studies of HRQOL in children with CF
relied on generic measures, such as the Child Health Questionnaire (CHQ) (Landgraf et al., 1996) and PedsQL™
(Varni et al., 1999). However, these measures have lacked
the sensitivity necessary to assess areas of functioning that
are critically important for children with CF, such as respiratory functioning and digestion. In addition, the Quality of Well-Being scale, a utility measure, has been used
with adolescents and adults with CF with mixed results
(Czyzewski, Mariotto, Bartholomew, LeCompte, & Sockrider, 1994; Orenstein, Pattishall, Nixon, Ross, & Kaplan,
1990). Note that utility measures were not originally de-
Cystic Fibrosis Questionnaire for Children
signed for use with children or adolescents. As a result,
researchers in France initiated the development of a
disease-specific HRQOL measure for children, adolescents/
adults, and parents of children with CF, the Cystic Fibrosis Questionnaire (CFQ) (Henry, Aussage, Grosskopf, &
Launois, 1996).
Cystic Fibrosis Questionnaire
French Model. In 1997, a CF-specific measure of HRQOL
was developed in France (Henry, Aussage, Grosskopf, &
Goehrs, 2003; Henry et al., 1996). In the first phase of
testing, 20 items were generated for the CFQ-Child version. Items were identified through extensive review of
the literature and interviews with experts in the field and
individuals with CF and their parents. Items on the questionnaires covered several key areas, including six generic
(e.g., physical functioning, psychological/emotional functioning, energy/fatigue) and four disease-specific domains
(e.g., eating disturbances, body image, treatment constraints). Subsequent phases of testing utilized Principal
Axis Factoring and multitrait analyses to reduce the item
pool for the final questionnaire, as well as test its initial validity. Internal consistency coefficients ranged from .46
to .71 for the CFQ-Child (Henry et al., 1998).
U.S. Model. First, a translation and linguistic validation
of the CFQ was performed in the United States (Quittner,
Sweeny, et al., 2000) following international guidelines
for the translation and validation of HRQOL measures
from one language to another (see Quittner, Sweeny, et
al., 2000, for a complete description of this process).
Next, a national validation study of the English CFQParent, CFQ-Child, and CFQ-Teen/Adult was conducted
at 18 different CF centers (Quittner, Buu, Watrous, &
Davis, 2000). Results from this study yielded good internal consistency coefficients for most scales, with the exception of the Treatment Burden and Social scales. One
item was added to each scale to improve internal consistency coefficients. Results also suggested that the measure could be downwardly extended to younger children.
In addition, two different true-false scales were evaluated
in the national validation study, with results indicating
that children had problems rating the middle of the continuum (i.e., very false, somewhat false, and somewhat true
to very true). Therefore, a simpler true-false scale was
adopted for the CFQ-Child. In sum, because a number
of changes were made to the CFQ-Child, further psychometric testing of the instrument was needed.
The purpose of the current study was to assess the
reliability and validity of a new, disease-specific HRQOL
measure for children with CF. Several predictions were
made regarding the psychometric properties of the instrument. First, items were expected to correlate more
strongly with their hypothesized than competing scales.
Second, internal consistency coefficients for the scales
were expected to be >.60, which is regarded as acceptable for newly developed scales (Ware et al., 1980). Third,
in terms of predictive validity, significant relationships
were expected between the CFQ-Child scales and health
status (e.g., pulmonary functioning). Specifically, strong associations were expected between physical domains (e.g.,
respiratory, physical, treatment burden) and pulmonary
functioning. Finally, convergence was expected between
the parent and child versions of the CFQ, particularly for
the Physical, Treatment Burden, Respiratory, Digestive,
Body Image, and Eating scales.
Method
Participants
Eighty-four participants and their parents were recruited
as part of a larger study examining the effectiveness of
three different airway clearance techniques for children,
adolescents, and adults with CF (Accurso, 1999). Participants were recruited from 22 geographically representative CF centers across the United States, comprising 4% of
participants from the West, 24% from the Midwest, 32%
from the Northeast, 39% from the South, and 1% from
Puerto Rico. (No significant differences were found between participants from these regions on pulmonary functioning and HRQOL scales, with the exception of the social scale, suggesting that the groups were homogeneous.)
Potential participants and their parents were approached
during routine clinic visits while waiting for their
appointments.
Patients were included in the study if they met the
following criteria: (a) a proven diagnosis of CF as evidenced by a positive sweat test or the presence of two
known CF mutations; (b) age 7 to 13 years; (c) forced expiratory volume in one second (FEV1) greater than 45%
predicted; and (d) willingness to participate and comply
with study procedures. Participants were excluded from the
study if they had been hospitalized for complications of CF
or any respiratory exacerbations resulting in antibiotic
treatments or were using investigational drugs.
The mean age of children was 9.5 years, ranging from
7 to 13 years of age. Forty-eight percent of the participants were female (see Table I). Illness severity, as measured by FEV1, ranged from 53% to 124% predicted, with
a majority of children (88%) falling into the mild category (≥70% predicted).
Procedure
Research coordinators completed specialized training in
order to standardize the study protocol across sites and


Modi and Quittner
Table I. Demographic Data (N = 84)
Age, y
Gender
Girls
Boys
Race (N = 83)
Caucasian
African American
Hispanic
Other
Disease Severity
(FEV1 % predicted)
Mild (≥ 70)
Moderate (40 –69.9)
Severe ( ≤ 39.9)
n
M
SD
Range
84
9.5
2.1
7–13
%
40
44
48
52
72
3
7
2
86
44
8
2
84
74
10
0
91.5
15.8
53 –124
88
12
0
FEV1= forced expiratory volume in one second
to recruit and screen participants, administer consent
forms, and instruct or administer questionnaires to both
children and their parents. The protocol and consent forms
were approved by the institutional review board at each
site.
The CFQ-Child version was administered by the research coordinator to all children. Parents of participants
were asked to complete a demographics questionnaire
and the CFQ-Parent version, a proxy measure of HRQOL
for children with CF. After completion of both versions
of the CFQ, pulmonary functioning tests and physical exams were conducted to assess health status.
Measures
Cystic Fibrosis Questionnaire–Child Version. The CFQChild is a disease-specific HRQOL measure for children
with CF between the ages of 6 and 13 (Quittner, Buu, et al.,
2000). Two versions of the CFQ-Child were established: an
interviewer-administered version for children 6 –11 years
of age and a self-report version for 12 –13 year olds. The
CFQ-Child is a 33-item instrument that assesses multiple
domains of HRQOL. This questionnaire includes three
broad domains of HRQOL, including Physical Symptoms
(6 items), Emotional Functioning (8 items), and Social
Functioning (5 items). The CFQ-Child also assesses five
domains specific to CF, which include Body Image (3
items), Eating Disturbances (3 items), Treatment Burden
(3 items), Respiratory Symptoms (4 items), and Digestive Symptoms (1 item). Seventeen items required a truefalse rating on a 4-point scale ranging from not at all true
to very true. Sixteen items required a frequency response
ranging from always to never on a 4-point scale. Children
were presented with true-false ratings on an orange card
and with frequency ratings on a blue card. They were
trained to use the response scales with two practice items
using the colored rating cards. The CFQ-Child took
approximately 15 minutes to complete. Raw scores for
each of the eight scales were converted into standardized
scores (0 –100), with higher scores representing better
HRQOL.
Cystic Fibrosis Questionnaire–Parent Version. The CFQParent is a measure of the parent’s report of their child’s
HRQOL for children aged 6 to13 (Henry et al., 2003;
Quittner, Buu, et al., 2000). It is a 43-item self-report measure that assesses four broad domains: Physical Symptoms
(9 items), Emotional Functioning (5 items), Vitality (5
items), and School Functioning (3 items); and seven CFspecific domains: Eating Disturbances (3 items), Body Image (3 items), Treatment Burden (2 items), Respiratory
Symptoms (6 items), Digestive Symptoms (3 items), and
Weight (1 item), along with an overall Health Perception
scale (3 items). The CFQ-Parent took approximately 15 –
20 minutes to complete. Raw scores were converted into
standardized scores (0 –100) for each of the 11 scales,
with higher scores indicating better HRQOL.
Health Status/Spirometry. Pulmonary function tests are
the gold standard for measuring respiratory functioning
and lung damage for individuals with CF. Specifically,
FEV1 % predicted is the primary biological indicator of
health status, using the Knudson equations for age, sex,
and weight (Knudson, Slatin, Lebowitz, & Burrows, 1976).
Illness severity ratings are based on established cutoffs
for mild (≥ 70%), moderate (40 –69%), and severe (≤ 39%)
disease (Taussig, 1995).
Statistical Analyses
Descriptive statistics (means and standard deviations)
were used to characterize the demographic variables. To
conduct item-level analyses, items were subjected to a
multitrait analysis (MAP-R program; Ware, Harris, Gandek,
Rogers, & Reese, 1997). Item-internal consistency was
evaluated by correlating each item with its own scale, corrected for overlap. Item-discriminant validity was assessed
by determining the percentage of items that correlated
higher with their hypothesized scale than a competing
scale. This was computed for each of the eight CFQ-Child
scales. Furthermore, the range of item responses was assessed by observing the percentage of respondents who
reported the maximum (ceiling effects) and minimum
(floor effects) possible responses. Ceiling and floor effects
of > 20% were considered significant (McHorney, Ware,
Lu, & Sherbourne, 1994).
For scale-level analyses, internal consistencies were
Cystic Fibrosis Questionnaire for Children
calculated using Cronbach α coefficients. Although coefficients of r = .70 are recommended to compare groups
(Nunnally & Bernstein, 1994), Ware and colleagues (1980)
have suggested that alpha coefficients ≥.60 are considered
acceptable for newly developed scales.
To examine construct validity, Pearson product moment correlation coefficients were calculated to determine
the relationship between health status (FEV1 % predicted)
and CFQ-Child scaled scores (predictive validity). Paired
correlations were used to determine the convergence of
parent and child report of the child’s HRQOL. Next,
Student t tests were conducted to examine gender differences in the child’s HRQOL. Finally, Pearson correla-
tions were conducted between CFQ-Child scores and
child’s age.
Results
Item-Level Analyses
Multitrait analyses indicated that a majority (56%) of the
items on the CFQ-Child correlated more strongly with
their hypothesized than competing scales, using Ware’s
criteria of .40 or higher as a scaling success (Ware et al.,
1980) (see Table II). Item-to-scale correlations were low for
several items on the Emotion, Body Image, Social, and
Treatment Burden scales. At the scale level, scaling suc-
Table II. Multitrait Analyses: Cystic Fibrosis Questionnaire—Child Version (N = 84)
Itema
Physical 17
Physical 18
Physical 19
Physical 20
Physical 21
Physical 22
Emotion 33
Emotion 42
Emotion 53
Emotion 73
Emotion 93
Emotion 10
Emotion 12
Emotion 13
Social 25
Social 26
Social 27
Social 28
Social 29
Body Image 30
Body Image 31
Body Image 32
Eating 14
Eating 16
Eating 24
Treatment 15
Treatment 23
Treatment 33
Respiratory 34
Respiratory 35
Respiratory 36
Respiratory 37
Digestive 38
M
SD
Physical
Emotion
Social
Body
Image
Eating
Treatment
Respiratory
Digestive
3.32
3.46
3.49
2.98
3.56
3.56
.42
.90
.17
.26
.39
3.44
3.29
3.54
3.18
3.04
3.01
2.85
3.27
3.12
3.63
3.29
3.58
3.45
3.58
3.30
3.50
3.25
2.71
3.69
3.29
3.65
3.27
.81
.88
.83
.93
.84
.86
.78
.79
.73
.70
.68
.65
.90
.72
.89
1.05
1.16
1.05
1.00
1.20
.86
1.05
.78
.92
.79
.80
.70
.94
.77
.66
.80
.61
.80
.57
.68
.47
.44
.46
.17b
.32
.40
.10
.22
.40
.42
.40
.38
.38
.37
.34
.18
.23
.28
.14
.39
.30
.14
.34
.18
.24
.17
.13
.46
.12
.48
.39
.41
.47
.36
.37
.33
.34
.34b
.47
.43
.33
.58
.43
.19b
.38b
.35
.32
.36
.26
.37
.34
.24
.48
.41
.14
.32
.09
.10
.26
.28
.52
.28
.44
.38
.34
.33
.35
.41
.34
.10
.21
.30
.37
.25
.47
.36
.20
.31
.44
.38b
.27b
.43
.27b
.26
.36
.41
.16
–.02
.12
.09
.08
.21
0.0
.17
.01
.31
.14
.15
.22
.25
.22
.37
.22
.27
.36
.21
.16
.43
.08
.20
.43
.28
.38
.04
.24
.47
.52
.39b
.36b
.21
.27
.29
–.04
–.01
.15
.09
.26
.08
.26
.22
.06
.25
.31
.10
.35
.12
.21
.30
.17
.08
.16
.11
.23
.25
.17
–.03
.11
.07
.06
.18
.33
.21
.63
.58
.59
.17
.20
.11
.04
.36
.16
.26
.20
.22
.15
.34
.31
.05
.01
.18
.18
.29
–.01
.14
–.02
.13
.15
.18
.24
.04
.13
.01
.05
–.02
.10
.15
.09
.33
.23b
.32b
.26b
.10
.07
–.08
.18
.06
.26
.33
.19
.16
.32
.27
.36
.36
.27
.13
.40
.29
.24
.33
.09
.05
.08
–.04
.31
.07
.26
.22
.38
.06
.27
–.03
.14
.07
.47
.50
.46
.36b
.33
.29
.33
.16
.16
.24
.34
.28
.25
.13
.09
.33
.23
.14
.27
.10
.07
0.0
.11
.16
.19
.18
.12
.32
.12
.07
.13
–.01
0.0
.23
.37
.08
.30
—
Values in boldface have the item-scale correlation corrected for overlap (relevant item removed from its scale for correlation). These correlations are also hypothesized to
be the highest in the same row. Standard error = .11
a
Item refers to the scale type and item number on the CFQ measure.
b
Less than desirable item internal consistency: item-scale correlation < .40


Modi and Quittner
cesses ranged from 86% for the Emotion, Social, and Body
Image scales to 100% for the Eating scale.
Minimal floor effects were found for the CFQ-Child
scales (0 –2%). Ceiling effects across the eight CFQ-Child
scales were generally minimal. However, a tendency to
endorse higher HRQOL scores was observed for the Eating (51%), Digestive (46%), and Body Image (40%) scales.
Scale-Level Analyses
Internal consistency coefficients are presented in Table
III. Seven of the eight CFQ-Child scales exceeded the
minimum alpha coefficients of .60 for reliability. These
reliability coefficients represent an improvement over the
national validation study. The alpha coefficient for the
treatment burden scale was .44, suggesting low internal
consistency. In order to assess whether younger children
could reliably complete the CFQ-Child, internal consistencies for the CFQ-Child scales were also computed separately for younger (7– 8 year olds) and older children
(9 –13 year olds) in the sample. There was no evidence
that younger children were less reliable in responding to
the CFQ than older children. Cronbach’s α ranged from .46
to .87 for younger children, and from .43 to .64 for older
children.
Construct Validity
Predictive Validity. Correlations between health status, as
measured by pulmonary functioning (FEV1 % predicted),
and the CFQ-Child scales were conducted. Associations
between pulmonary functioning and CFQ scores were
low due to restricted range of disease severity (r = .01–
.18). No children in this sample were severely ill and only
12% were classified as moderately ill.
Convergent Validity. To examine convergence between
parent-child dyads, paired correlations between the CFQChild and CFQ-Parent were calculated. Significant agreement was found for the Body Image (r = .34, p < .01),
Eating (r = .37, p < .01), Treatment Burden (r = .22, p <
.05), Digestion (r = .24, p < .05), and Respiratory scales (r =
.32, p < .01). Despite the generally good agreement between parent and child reports, some differences were
noted in their scores. Paired t tests were also conducted,
which indicated that children reported lower HRQOL than
their parents on the following scales: Physical, t(79) = – 4.3,
p < .001; Emotion, t(79) = –3.2, p < .01; and Digestion,
t(79) = –3.0, p < .01 (see Table IV). Conversely, parents reported lower HRQOL for their children on the scales for
Treatment Burden, t (79) = 9.8, p < .001; Body Image,
t(79) = 2.1, p < .05; and Respiratory, t(78) = 2.2, p < .05.
Gender and Age Differences
T tests were used to evaluate potential differences between
males and females on each of the eight CFQ-Child scales.
A significant difference between males and females was
found on the respiratory scale, with females scoring lower,
t(82) = 2.1, p < .05. A post hoc analysis was conducted
to examine differences in pulmonary functioning for males
and females. Females had a mean FEV1 of 92.1% predicted
and males had a mean FEV1 % predicted of 92.3, indicating no substantial difference in pulmonary functioning.
Similarly, few significant associations were found between
CFQ-Child scores and age, with the exception of the Digestion scale (r = .23, p < .05). Older children reported
higher HRQOL scores on the Digestion scale than younger
children.
Discussion
The overall purpose of this study was to evaluate the reliability and validity of an HRQOL instrument for children with CF. The CFQ-Child is a developmentally appropriate, disease-specific HRQOL measure that was
designed to account for the multisystem nature of the disease and provide health care professionals with a precise
Table III. Internal Consistency/Coefficientsa
CFQ-Child Scales
Physical
Emotion
Social
Body Image
Eating
Treatment Burden
Respiratory
Digestiveb
a
b
Cronbach’s α.
Scale contains only one item.
Total Sample
(7–13 year olds) n = 84
Younger Children
(7–8 year olds) n = 32
Older Children
(9–13 year olds) n = 52
.72
.69
.60
.60
.76
.44
.66
—
.80
.77
.57
.64
.87
.46
.76
—
.63
.60
.61
.59
.64
.43
.56
—
Cystic Fibrosis Questionnaire for Children
Table IV. Means and SDs for Cystic Fibrosis Questionnaire (CFQ)—Child and CFQ-Parent Scales (n = 80)
Child
Scales
Physical
Emotion
Body Image
Eating
Treatment Burden
Respiratory
Digestive
Parent
M
SD
M
SD
t (79)
79.4
76.4
77.5
84.7
78.8
77.8
75.4
18.8
14.1
26.3
23.2
19.1
16.4
26.9
89.6
83.4
69.7
81.0
54.2
73.3
84.6
12.0
14.0
30.9
25.7
16.5
15.3
14.7
– 4.3***
–3.2**
2.1***
1.2
9.8***
2.2***
–3.0**
*p < .001
**p < .01
***p < .05
and sensitive measure of daily functioning (Quittner, Buu,
et al., 2000).
In terms of item-level analyses, a majority of the
items demonstrated adequate item-internal and itemdiscriminant validity. This suggests that the CFQ-Child
exhibits both content and discriminant validity. Items on
the CFQ-Child were also able to elicit a range of responses
from the positive to the negative end of the scale, with
little pooling at the extreme ends. Negligible floor effects
were found, suggesting that the instrument is valid for
CF patients experiencing significant health problems and
thus potentially low HRQOL. Ceiling effects were noted for
three scales (eating, digestive, and body image), indicating
that respondents tended to endorse higher ratings of
HRQOL on these scales. However, in comparison with
generic HRQOL measures for children, such as the widely
used CHQ and PedsQL™, these ceiling effects were minimal. Note that substantial ceiling effects have been found
on one third of the scales on the CHQ across several
chronic disease groups, including asthma, epilepsy, and
juvenile rheumatoid arthritis (Landgraf et al., 1996).
Internal consistency coefficients indicated that this
version of the CFQ is reliable. This may be partly attributable to the adoption of a simpler true-false scale for
children. Only the Social and Treatment Burden scales
demonstrated low reliability. As a result, one item was revised in the Treatment Burden scale and one item was
added to the Social scale to increase their reliability. These
additional items will be tested in subsequent studies of
the CFQ.
The downward extension of the CFQ-Child appeared
to be successful. Internal consistency coefficients for the
younger age group (7– 8 years) were as high as those for
the older group, indicating that younger children can
reliably complete the CFQ-Child measure. Alpha coefficients for the older sample were slightly lower than
those for the younger sample, which may be explained by
the the older children’s greater tendency to respond in a socially desirable manner, particularly in the intervieweradministered version. A self-report version of the CFQChild was created for 12 –13 year olds in order to reduce
these problems and will continue to be evaluated in future
studies.
The relationship between health status variables and
HRQOL was also evaluated in this study. No associations
were found between pulmonary functioning and CFQ
scores. This was likely due to the restricted range of disease severity in younger children with CF. It is important
to note that inclusion criteria for the larger airway clearance study involved recruiting children with FEV1 > 45%
predicted, thus excluding children who were severely ill.
Average pulmonary functioning reported for the larger
national validation study was similar to the one reported
here, indicating that the sample recruited for this study
was typical with respect to pulmonary functioning for this
age group (Quittner, Buu, et al., 2000). The CFQ has been
found to discriminate between levels of disease severity in
adolescent and adult populations, for whom there is a
wider range of pulmonary functioning (Modi, Quittner,
Davis, & Buu, 2002; Quittner, Buu, et al., 2000). A recent study examining HRQOL in children with CF with
greater disease severity (e.g., children hospitalized for pulmonary exacerbations) yielded substantially lower mean
values on the CFQ (Quittner, Stack, Modi, & Davis, 2002),
indicating that the measure is sensitive to changes in pulmonary functioning.
Another important issue in HRQOL research is the
extent to which parents and children agree on the affected
child’s HRQOL. There have been mixed results in the literature regarding the importance of child versus parentproxy reports of HRQOL. Prior research has questioned the
validity and utility of parent-proxy measures of HRQOL,
since the parent’s own emotional functioning may affect the
ratings of the child’s HRQOL (Vance, Morse, Jenney, &


Modi and Quittner
Eiser, 2001). However, the parent’s report of the child’s
HRQOL is an important method for identifying changes in
health status that children may be less aware of, such as increased symptoms or changes in daily functioning. More
recently, there has been an impetus to measure HRQOL by
asking children themselves about the impact of the illness on their daily life. This is a critical perspective that,
in conjunction with the parents’ views, may more effectively guide health care professionals in their treatment
planning or evaluation of behavioral interventions (Quittner, Drotar, et al., 2000).
In the current study, results indicated strong convergence between parents (primarily mothers) and their children on the Body Image, Eating, Treatment Burden,
Digestive, and Respiratory domains. No significant associations were found for the Physical and Emotional functioning domains. Parents rated the Treatment Burden scale
lower in comparison with their children’s reports, which
may reflect the parents’ view that the treatment regimen for
CF is burdensome for them. In contrast, children reported
lower HRQOL on the Emotion scale in comparison with
parents. This finding may suggest that young children
have difficulty expressing their emotions directly to their
parents. Measures of HRQOL in other populations have
also found higher patient/proxy concordance for observable domains, such as physical functioning, and lower
agreement between children and their parents on emotional and social functioning (Landgraf et al., 1996; Verrips, Vogels, den Ouden, Paneth, & Verloove-Vanhorick,
2000). In contrast, ratings of internalizing problems may
require the child to verbally report his/her feelings. Thus,
administering an HRQOL measure such as the CFQ-Child
can provide the health care team with the child’s perspective on his/her emotional and social functioning.
In terms of gender differences in HRQOL, epidemiological studies have indicated that female patients with
CF have a significantly poorer prognosis and shorter life
span than age-matched males. Generally, females with CF
have a more rapid decline in pulmonary functioning each
year beginning soon after puberty, which decreases their
median survival age by approximately 4 years in comparison with males (Davis, 1999; O’Connor et al., 2002). Although several reasons for this gender difference have
been explored (e.g., nutritional status, airway microbiology), this “gender gap” in survival has not yet been explained. Differential patterns in HRQOL might shed light
on the underlying causes of this gender difference. In the
current study, females reported significantly lower on the
Respiratory HRQOL scale than males. One explanation
for these results is that the CFQ-Child may be sensitive to
early changes in pulmonary functioning, such as increased
coughing and wheezing, that may not be detected in a
standard pulmonary functioning test.
Despite the generally strong psychometric findings
of this study, several limitations were noted. First, the
sample size was relatively small and it is possible that
stronger evidence of reliability and convergent validity
might have been found with a larger sample size and increased power. In addition, a substantial proportion of
items did not meet the criteria for item-level scaling success. Although many of these items were close to meeting
the .40 standard, problems were identified for items on
the Emotion, Social, and Treatment Burden scales. Additional items were revised or added to these scales. Moderate ceiling effects were found for the Body Image, Eating,
and Digestive scales; however, the restricted range of disease severity in this sample may have contributed to these
effects.
This new, disease-specific HRQOL measure for CF
has wide applicability for basic research, as well as for behavioral and pharmacological intervention trials. There
is an increasing focus on international drug trials, which
require validated HRQOL measures in several languages.
The CFQ has now been translated into German, Dutch,
Portuguese, Spanish, Italian, and Greek. It has also been
used in several national studies to examine the impact of
antibiotics and airway clearance techniques on HRQOL
(Modi et al., 2001; Quittner et al., 2002; Saiman et al., in
press). HRQOL data, in conjunction with traditional health
outcome measures such as FEV1 % predicted, should further our understanding of the impact of these treatments
on the lives of patients with CF.
An important next step is to establish national norms
for the CFQ. The CFQ is now being added to the data
collected annually for a national database in the United
States (Quittner, Modi, & Davis, 2003). Establishment of
a normative database would enable health care professionals to compare an individual’s reports of HRQOL with
those of other children who are similar in age, gender,
and disease severity. This information could be used to
identify areas of risk for an individual patient, document
the benefits of new treatments, and inform medical decision making. For example, if a child reported a decrease in
physical and respiratory functioning on the CFQ, physicians might choose to prescribe rhDNase to increase respiratory functioning.
Another area for future research is determination of
the minimal clinically important difference (MCID) for
the CFQ. The MCID is defined as “the smallest difference
in score, in the domain of interest, which patients perceive as beneficial and which would mandate, in the absence of troublesome side-effects and excessive cost, a
Cystic Fibrosis Questionnaire for Children
change in the patient’s management” (Jaeschke, Singer,
& Guyatt, 1989).
Finally, integrating the assessment of HRQOL into
clinical practice has considerable promise (Drotar et al.,
1998; Williams & Williams, 2003). For example, the CFQ
could be completed during yearly clinic visits to monitor
functioning in a variety of domains. This process could
be computerized so that the health care team could examine the patients’ scores or HRQOL profile in real time,
which may alert them to recent changes in functioning.
These data would enable health care providers to tailor
treatment needs to the individual and provide him /her
with comprehensive medical and psychological care.
The CFQ measures and scoring manual may be obtained
free of charge by contacting the authors.
Acknowledgments
This study was funded in part by the Cystic Fibrosis Foundation. We also acknowledge the support of our colleagues
on the larger national Airway Clearance Study, Dr. Frank
Accurso, Ms. Marci Sontag, and Ms. Joni Koenig. Finally,
we extend our deepest appreciation to the children with
cystic fibrosis and their families who participated in this
study, as well as the nurses and research coordinators at the
22 CF centers across the United States who recruited participants and collected the data.
Received December 19, 2002; revisions received February
12, 2003; accepted March 31, 2003
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