Reliability and validity of the Cystic Fibrosis Questionnaire-Revised for children and parents in Turkey: cross-sectional study.
ABSTRACT PURPOSE: The purpose of study was to translate Cystic Fibrosis Questionnaire-Revised (CFQ-R) into Turkish for children with cystic fibrosis (CF) and evaluate its reliability and validity. This is the first CF-specific health-related quality of life (HRQOL) measure validated in a Muslim country. METHODS: Fifty-one children aged 6-13 years treated at four centers in Turkey and 30 parents participated in this cross-sectional study. Demographic characteristics and disease severity parameters were recorded for all participants. All participants completed the parent or child versions of CFQ-R and KINDL questionnaires at enrollment. Reliability and construct validity analysis were carried out. RESULTS: Both children and parents endorsed a range of responses, with no evidence of floor or ceiling effects. Item-to-total correlations indicated that most items were more highly correlated with their intended scale than competing scales. Good internal consistency was found for majority of child and parent scales. CFQ-R scales correlated significantly with clinical indices of disease severity. Good evidence of convergent validity with a generic HRQOL scale was found. CONCLUSION: Turkish versions of CFQ-R Child and Parent instruments have demonstrated adequate reliability and validity and can be utilized in clinical trials or integrated into clinical evaluation and follow-up of Turkish children with CF.
- SourceAvailable from: Alexandra L Quittner[Show abstract] [Hide abstract]
ABSTRACT: 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). The CFQ was administered to 84 children with CF, ranging in age from 7 to 13 years, and their parents. 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 alpha =.60-.76), with the exception of treatment burden (Cronbach's alpha =.44). Results also suggested strong convergence between child and parent-proxy reports on several scales of the CFQ. Results demonstrated that the CFQ-Child is a reliable and valid measure of HRQOL for children with CF.Journal of Pediatric Psychology 01/2004; 28(8):535-45. · 2.91 Impact Factor
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ABSTRACT: Health related quality of life (HRQoL) measurement is important in determining the impact of disease on daily functioning and subsequently informing interventions. In cystic fibrosis (CF) generic HRQoL measures have been employed but these may not be sufficiently specific. The aim of the current work was to develop and validate a disease specific HRQoL measure for adults and adolescents with cystic fibrosis. Areas of concern to adults and adolescents with CF were identified by unstructured interviews, self-administered questionnaires, consultation with multidisciplinary specialist staff, a review of the relevant literature, and examination of other HRQoL measures. Items for the questionnaire were generated on the basis of this process. Continued evaluation and development of the Cystic Fibrosis Quality of Life (CFQoL) questionnaire was undertaken by a process of statistical analysis and continued feedback from patients. The full testing and validation of the CFQoL questionnaire took place over four phases: (1) initial item generation and testing of a preliminary questionnaire, (2) testing and validation of the second version of the questionnaire, (3) test-retest reliability of a third and final version of the questionnaire, and (4) sensitivity testing of the final version of the questionnaire. Nine domains of functioning were identified using principal components analysis with varimax rotation. Internal reliability of the identified domains was demonstrated using Cronbach alpha coefficients (range 0.72-0.92) and item to total domain score correlations. Concurrent validity (range r = 0.64-0.74), discriminatory ability between different levels of disease severity, sensitivity across transient changes in health (effect size range, moderate d = 0.56 to large d = 1.95), and test-retest reliability (r = 0.74-0.96) were also found to be robust. The CFQoL questionnaire is a fully validated disease specific measure consisting of 52 items across nine domains of functioning which have been identified by, and are of importance to, adolescents and adults with cystic fibrosis. This measure will be useful in clinical trials and longitudinal studies.Thorax 12/2000; 55(11):946-54. · 8.38 Impact Factor
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ABSTRACT: There are few health-related quality of life (HRQOL) instruments available that have been validated for use with Turkish children. The Kid-KINDL is a generic measure of children's (8-12 years) HRQOL, which contains 24 categorical items that assess 6 dimensions (physical well-being, emotional well-being, self-esteem, family, friends, and school). The Kid-KINDL is available in many languages. Following an elaborate translation procedure and cognitive focus group interviews, the Kid-KINDL was adopted into Turkish. This paper describes the psychometric properties of the new Turkish Kid-KINDL. In total, 1918 children aged 8-12 years at a school in Manisa completed the Kid-KINDL. A confirmatory approach was used for validity and reliability analysis. Using the Multi-trait/Multi-item analysis program (MAP) item-internal consistency and item-discriminant validity were calculated to confirm the instrument's structure. Likert scaling assumptions were tested and confirmatory factor analysis (CFA) was applied as well. After modification of 2 unsatisfactory items the Kid-KINDL was administered to a different group of 84 randomly selected children and the analyses were repeated. Cronbach's alpha was 0.35-0.78 before and 0.54-0.78 after the scales was modified. MAP-scaling success was 60%-100% before and 90%-100% after the modification. CFA confirmed the Kid-KINDL structure for the original version (RMSEA = 0.077) was less than the modified version (RMSEA = 0.059), although for the latter the sample was rather small. Floor effects were negligible, and ceiling effects reached 19%. The results indicate that the Turkish Kid-KINDL was a reliable and factorially valid assessment of the children's HRQOL. The modifications made to the 2 unsatisfactory items increased the psychometric quality of the scale.Turk psikiyatri dergisi = Turkish journal of psychiatry 02/2008; 19(4):409-17. · 0.43 Impact Factor
Reliability and validity of the Cystic Fibrosis Questionnaire-
Revised for children and parents in Turkey: cross-sectional study
Hasan Yuksel•Ozge Yilmaz•Deniz Dogru•
Bulent Karadag•Fatih Unal•Alexandra L. Quittner
Accepted: 1 March 2012/Published online: 11 April 2012
? Springer Science+Business Media B.V. 2012
Fibrosis Questionnaire-Revised (CFQ-R) into Turkish for
children with cystic fibrosis (CF) and evaluate its reliability
and validity. This is the first CF-specific health-related
quality of life (HRQOL) measure validated in a Muslim
Fifty-one children aged 6–13 years treated at
four centers in Turkey and 30 parents participated in this
cross-sectional study. Demographic characteristics and
disease severity parameters were recorded for all partici-
pants. All participants completed the parent or child ver-
sions of CFQ-R and KINDL questionnaires at enrollment.
Reliability and construct validity analysis were carried out.
The purpose of study was to translate Cystic
responses, with no evidence of floor or ceiling effects.
Item-to-total correlations indicated that most items were
more highly correlated with their intended scale than
competing scales. Good internal consistency was found for
majority of child and parent scales. CFQ-R scales corre-
lated significantly with clinical indices of disease severity.
Good evidence of convergent validity with a generic
HRQOL scale was found.
Turkish versions of CFQ-R Child and Parent
instruments have demonstrated adequate reliability and
validity and can be utilized in clinical trials or integrated
into clinical evaluation and follow-up of Turkish children
Both children and parents endorsed a range of
Cystic fibrosis ? Validity ? Reliability
Cystic Fibrosis Questionnaire-Revised ?
It is critical to evaluate the impact of cystic fibrosis (CF)
and its treatment on patients’ health-related quality of life
(HRQOL) [1, 2]. HRQOL measures, which fall under the
category of patient-reported outcomes, are now being used
in descriptive studies, as well as clinical trials [3–7].
Evaluation of HRQOL in patients with CF is important
because it adds unique information that is not captured by
traditional clinical parameters. In addition, as patients’
disease trajectories improve, these traditional outcome
measures may not be sensitive indicators of the effects of
new treatments .
The Cystic Fibrosis Questionnaire-Revised (CFQ-R) is
the most widely used HRQOL instrument for CF [1, 9]. No
reliable and valid HRQOL instrument for patients with CF
H. Yuksel ? O. Yilmaz
Department of Pediatric Allergy and Pulmonology,
Medical Faculty, Celal Bayar University, Manisa, Turkey
H. Yuksel (&)
116/17 Sokak No: 7 C Blok Daire 3, 35050 Bornova,
Department of Pediatric Pulmonology, Medical Faculty,
Hacettepe University, Ankara, Turkey
Department of Pediatric Pulmonology, Medical Faculty,
Marmara University, Istanbul, Turkey
Bursa Children’s Hospital, Bursa, Turkey
A. L. Quittner
Department of Psychology, University of Miami, Coral Gables,
Qual Life Res (2013) 22:409–414
in Turkey or any other Muslim country currently exists.
Further, European Cystic Fibrosis Society (ECFS) is cur-
rently establishing a clinical trials network, with a focus on
improving the health outcomes of patients with CF across
Europe, making it essential to have measures that can be
used in all of these countries. Thus, the major aim of this
study was to translate the CFQ-R into Turkish for children
with CF and their parents, and perform an initial evaluation
of the instrument’s psychometric properties.
Subjects and study design
The CFQ-R questionnaires for children and parents were
translated into Turkish and then validated in a multicenter
cross-sectional study . Children with CF presenting to
the centers were enrolled consecutively during the study
period. Demographic characteristics and clinical indicators
of disease severity were recorded. Clinical severity
parameters recorded included number of hospitalizations
due to a CF-related health problem, number of exacerba-
tions related pulmonary findings that required treatment,
and number of presentations to the outpatient department
or emergency room due to a CF-related health problem that
was not routine other than routine control during the pre-
vious 1-year period. Data on clinical severity parameters
were collected over a 1-year period from a systematic chart
All children completed age-appropriate CFQ-R and a
general HRQOL measure, the questionnaire for measuring
HRQOL in children and adolescents (KINDL). Parents
completed CFQ-R Parent version. All instruments were
completed during a visit to the department under the
supervision of the pediatrician involved in the study.
The study was approved by the Institutional Ethics
Board of Celal Bayar University and informed consent was
obtained from participants.
Cystic Fibrosis Questionnaire-Revised questionnaire
The CFQ-R is a disease-specific HRQOL questionnaire [2,
11]. CFQ-R Child version consists of 35 questions on the
following scales: Physical Functioning, Emotional Func-
tioning, Social Functioning, Body Image, Eating Distur-
bances, Treatment Burden, and Respiratory and Digestive
symptoms. The CFQ-R Parent version is a self-report
instrument composed of 44 items grouped into 11 domains
that assess Physical Functioning, Emotional Functioning,
Vitality, School Performance, Eating Disturbances, Body
Image, Treatment Burden, Health Perceptions, Respiratory
and Digestive Symptoms, and Weight. Both instruments
have well-established reliability and validity [11, 12].
Items for both child and parent CFQ-R are rated according
to a 4-point scale. Higher scores indicate better HRQOL.
The KINDL Questionnaire is a generic HRQOL [13–15]. It
consists of 24 items rated on Likert-type scales evaluating
six domains of HRQOL: physical well-being, emotional
well-being, self-esteem, family, friends, and everyday
Translation of CFQ-R’s into Turkish
The translation process consisted of initial forward trans-
lation from English into Turkish by two independent,
native Turkish speakers. Translations were discussed with
the developer of CFQ-R in several conference calls and
‘‘consensus’’ translation in Turkish was developed. Next,
Turkish version was back-translated into English by two
independent translators, followed by discussion with the
developer. Minor revisions were made to the Turkish ver-
sions of CFQ-R. Finally, cognitive debriefing was per-
Statistical analyses were performed using SPSS 13.0
(Chicago, IL, USA), with p values less than 0.05 consid-
ered statistically significant. Kruskal–Wallis test and
Mann–Whitney U and student’s t test were used to com-
pare CFQ-R scores in different sociodemographic groups.
To assess reliability, we calculated item-to-total corre-
lations using Pearson correlations; we evaluated internal
consistency using Cronbach’s alpha. We assessed construct
validity by examining correlations between CFQ-R and
KINDL, as well as between CFQ-R scores and clinical
Sociodemographic characteristics of the participants
A total of 51 children with CF and 30 parent caregivers
participated. Mean age of children was 9.8 years ± 2.6
Few gender differences were found on the CFQ-R
domain scores; girls scored significantly higher on Emo-
tional Functioning, indicating better functioning, than boys
(78.7 ± 13.9 vs 68.4 ± 11.9, p = 0.003).
Mean age of parents was 35.5 ± 5.3 years, with a range
of 26–47. Most parents were mothers (83.3 %) (Table 1).
410 Qual Life Res (2013) 22:409–414
There were no significant associations between age of
the child or parent and CFQ-R scores (p’s[0.05). CFQ-R
scores did not change significantly in relation to level of
parental education (p’s C 0.05). Parents working outside
the home scored significantly higher (68.6, SD = 9.2) than
non-working parents (52.2, SD = 21.6) on Vitality scale
(p = 0.03).
There was no evidence of floor or ceiling effects on any
scales (defined as \10 or [90 %). Item-to-total correla-
tions supported the item structure of the CFQ-R, with a
majority of items correlating more highly with their
intended scale (Table 2). Two items on the CFQ-R Child
version demonstrated slightly lower correlations: item 13
(r = 0.29) and item 21 (r = 0.33). For the CFQ-R Parent
version, all items correlated better with their intended scale
than competing scales.
Internal consistency was adequate for most of CFQ-R
Child scales (Cronbach’s alpha above 0.60) exception for
Treatment Burden (alpha = 0.55) (Table 2) . Good
internal consistency was also found for all CFQ-R Parent
Scales (alphas 0.63–0.88), except School Functioning
(alpha = 0.37) (Table 2).
As hypothesized, scores on the CFQ-R Child instrument
were correlated with several clinical parameters in the
expected direction; children with lower lung function, for
example, reported more Respiratory Symptoms (Table 3).
For the CFQ-R Parent version, significant correlations were
also found between clinical indices of disease severity and
the CFQ-R scores (Table 3).
In terms of convergence between the CFQ-R, which is a
disease-specific instrument, and the KINDL, scores on the
Physical Functioning scale of the CFQ-R were correlated
with all domains of KINDL except the School domain
(r’s[0.31, p\0.03 for all scales; r = 0.27 p = 0.08 for
KINDL school domain). Emotional Functioning on both
scales was significantly correlated (r = -0.57, p\0.001)
and Emotional Functioning scale of the CFQ-R was also
significantly correlated with physical, self-esteem, friends,
and chronic disease domains of KINDL (r = 0.52 p\
0.001, r = 0.41 p = 0.003, r = 0.39 p = 0.005, r = 0.38
p = 0.008, respectively). The CFQ-R scales, including
Symptoms, and Digestion, were all significantly correlated
with physical domain of KINDL (r[0.38 p\0.008 for
all), demonstrating good convergent validity (Table 4).
This is the first study to translate and evaluate the psy-
chometric properties of the CFQ-R in a predominantly
Muslim country. It is critically important to have reliable
and valid disease-specific HRQOL instruments for all
European countries, as efforts are being made to develop a
Table 1 Sociodemographic characteristics of the children and par-
ents enrolled in the study
Child CFQ-R 6–13 years
Mean ± SD9.8 ± 2.6
Child CFQ-R 6–13 years
Child CFQ-R 6–11 years
Not attending school518.5
Child CFQ-R 12–13 years
Not attending school28.3
Grade 6 1458.3
Mean ± standard deviation35.5 ± 5.3
Education (last graduated school)
Less than high school2583.3
High school diploma1 3.3
Looking for job13.3
Working full/part time7 23.4
Cannot work for other reasons13.3
aEducation of the children enrolled in the study who filled in CFQ-R
6–11 and 12–13 years
Qual Life Res (2013) 22:409–414411
European Clinical Trials Network to evaluate efficacy of
new treatments and conduct comparative efficacy studies.
Therefore, availability of a validated HRQOL measure will
enable CF Centers and clinicians to better track outcomes
of their patients.
This study demonstrated that Turkish CFQ-R yields a
good range of scores, with no evidence of floor or ceiling
effects. Items fit better with their assigned scales than
competing scales and internal consistency of both the CFQ-
R Child and Parent versions was acceptable. The only scale
that did not demonstrate good internal consistency was
CFQ-R Parent School Functioning scale which may be due
to the low percentage of children attending school. Cron-
bach’s a coefficients for Danish CFQ-R have been reported
to range between 0.54 and 0.95, with a majority of the
coefficients above 0.70. Despite the similar range of
internal consistency coefficients between the Danish and
Turkish versions of the CFQ-R, generally higher coeffi-
cients were found in the Danish version . On the other
hand, Cronbach’s a coefficients for child version of the
German CFQ-R are closer to the Turkish values being
reported . This result highlights the potential differ-
ences in both the daily functioning and health outcomes of
children with CF in less industrialized countries.
Strong evidence of convergent validity was found both
in terms of associations between CFQ-R and a generic
quality of life measure and children’s health outcomes.
Specifically, good convergent validity was found between
the CFQ-R scores and the KINDL, a generic QoL measure,
especially in domains of functioning that were similar (e.g.,
emotional functioning). In contrast, no associations were
found between the CFQ-R Physical Functioning domain
and the similarly named KINDL scale. This is likely
because they ask about different physical abilities. Inter-
estingly, significant correlations were found between CFQ-
R scales that reflect physical aspects of the disease, such as
respiratory symptoms and digestion, and these were sig-
nificantly associated with the physical domain on the
KINDL. This difference in associations may reflect the
generic nature of KINDL in comparison with a disease-
specific tool like the CFQ-R. Generally, the results sup-
ported the construct validity of the instrument.
Further, significant associations were found between
several key CFQ-R scales (Physical Functioning, Respira-
tory Symptoms, Social Functioning, Treatment Burden)
and clinical parameters reflecting disease severity.
New developments in the treatment of CF over the past
20 years have led to longer life spans but an increase in
Table 2 Descriptive statistics, corrected item total correlations, and Cronbach alpha values for CFQ-R child and parent instruments
Min–maxRc(Min–max) Cronbach alpha
CFQ-R child version
Physical functioning (6)50.550.0 25.5 5.6–94.4 0.25–0.720.78
Emotional functioning (8)73.4 70.8 13.850.0–100.0 0.14–0.51 0.64
Social functioning (7) 56.2220.127.116.11–100.0 0.38–0.600.69
Body image (3)64.1 66.731.9 0.0–100.0 0.20–0.520.55
Eating disturbances (3)57.355.6 29.80.0–100.0 0.42–0.630.70
Treatment burden (3)70.877.8 23.811.1–100.0 0.44–0.560.72
Respiratory symptoms (4) 70.366.7 22.625.0–100.0 0.11–0.710.60
Digestion (1)77.8 66.7 27.20.0–100.0––
CFQ-R parent version
Physical functioning (9)53.4 55.628.43.7–100.00.43–0.790.88
Emotional functioning (8)59.160.022.9 20.0–100.00.25–0.510.63
Vitality (5)56.1 53.320.9 13.3–100.00.37–0.580.68
School performance (3)55.966.728.9 0.0–100.00.10–0.330.37
Eating disturbances (2)36.2 33.333.9 0.0–100.0 0.53–0.540.69
Body image (3) 50.655.6 36.1 0.0–100.00.40–0.700.73
Treatment burden (3) 45.644.4 31.90.0–100.00.48–0.68 0.75
Health perceptions (3)64.8 77.827.411.1–100.00.43–0.850.78
Respiratory symptoms (6) 65.518.104.22.168–100.00.53–0.800.86
Digestion (3) 83.988.9 22.9 11.1–100.00.75–0.770.87
Weight (1) 37.9 33.334.20.0–100.0––
aNumber of items
cCorrected item total correlations
412Qual Life Res (2013) 22:409–414
treatment burden . This is one reason that patient-
reported outcomes are needed. Moreover, clinical trial
endpoints that reflect respiratory symptoms and daily
functioning from the patient/caregiver perspective are
needed. Reliable and valid HRQOL measures are also
being used in clinical practice to monitor patient func-
tioning, and this may become more important as compar-
ative effectiveness trials are performed. HRQOL measures
may provide crucial evidence on which treatments are most
effective from the patient’s perspective in relation to the
burden of their administration. The CFQ-R has now been
translated into 34 languages and is being used in many of
the international clinical trials, including Turkey.
A major limitation of this study was the relatively small
size of both the patient and parent samples. Turkey has a
relatively small population of patients with CF (estimated at
1,000 across all ages) and major efforts were made to enroll
participants across 4 CF Centers in Turkey. The other lim-
itation isthe absenceofpulmonaryfunctiondata,which was
due to the young age of the children in this sample.
Future directions for the use of the CFQ-R in Turkey
include the translation and validation of the teen/adult
Table 3 Correlations between
CFQ-R child and parent
versions and clinical parameters
Figures in bold indicate
aNumber of hospitalizations
due to a CF-related health
problem during the previous
1 year period
bNumber of exacerbations in
CF-related pulmonary findings
that required treatment during
the previous 1 year period
cNumber of presentations to
the outpatient department or
emergency room due to a CF-
related health problem other
than routine control
CFQ-R child version
Eating disturbances-0.21 0.002-0.18
CFQ-R parent version
Emotional functioning-0.31-0.14 -0.37
Table 4 Correlations between CFQ-R Child Version and KINDL Total and Domain Scores
CFQ-R domainsKINDL domains
Physical role Emotional roleSelf-esteem FamilyFriendsSchool Chronic diseaseTotal
0.31 0.590.46 0.320.65
0.45 0.720.510.43 0.72
0.44 0.29 0.330.54
0.41 0.32 0.310.54
Figures in bold indicate statistical significance
Qual Life Res (2013) 22:409–414413
version of the CFQ-R, development of a national CF reg-
istry to track patients’ health outcomes, including HRQOL,
and use of the CFQ-R to improve clinical care. In addition,
the Turkish CFQ-R can now be incorporated into ongoing
clinical trials in Turkey.
In conclusion, Turkish versions of the CFQ-R Child and
Parent measures have demonstrated adequate reliability
and good validity, both in terms of the constructs that were
measured and their convergence with generic QoL mea-
sures and health outcomes. Incorporation of this instrument
into patient care as well as clinical trials should facilitate
steps toward improving the management and outcomes of
these patients and families.
1. Goss, C. H., & Quittner, A. L. (2007). Patient-reported outcomes
in cystic fibrosis. Proceedings of the American Thoracic Society,
2. Quittner, A. L., Modi, A. C., & Cruz, I. (2008). Systematic
review of health-related quality of life measures for children with
respiratory conditions. Pediatrıc Respiratory Reviews, 9(3),
3. Gee, L., Abbott, J., Conway, S. P., Etherington, C., & Webb, A.
K. (2000). Development of a disease specific health related
quality of life measure for adults and adolescents with cystic
fibrosis. Thorax, 55(11), 946–954.
4. Goldbeck, L., Schmitz, T. G., Henrich, G., & Herschbach, P.
(2003). Questions on life satisfaction for adolescents and adults
with cystic fibrosis: Development of a disease-specific question-
naire. Chest, 123(1), 42–48.
5. Henrich, G., Goldbeck, L., Schmitz, T. G., & Besier, T. (2010).
Measuring life satisfaction in children and adolescents–psycho-
metric properties of the ‘‘Questions on Life Satisfaction’’
FLZ(KJ). Psychotherapie, Psychosomatik, Medizinische Psy-
chologie, 60(6), 219–226.
6. Retsch-Bogart, G. Z., Quittner, A. L., & Gibson, R. L. (2009).
Efficacy and safety of inhaled aztreonam lysine for airway
Pseudomonas in cystic fibrosis. Chest, 135(5), 1223–1232.
7. McCoy, K. S., Quittner, A. L., Oermann, C. M., Gibson, R. L.,
Retsch-Bogart, G. Z., & Montgomery, A. B. (2008). Inhaled
aztreonam lysine for chronic airway Pseudomonas aeruginosa in
cystic fibrosis. American Journal of Respiratory and Critical
Care Medicine, 178(9), 921–928.
8. Quittner, A. L. (1998). Measurement of quality of life in cystic
fibrosis. Current Opinion in Pulmonary Medicine, 4(6), 326–331.
9. Quittner, A. L., Sawicki, G. S., McMullen, A., Rasouiliyan, L.,
Pasta, D. J., Yegin, A., et al. (Epub ahead of print). Psychometric
evaluation of the cystic fibrosis questionnaire-revised in a US
national sample. Quality of Life Research.
10. Yuksel, H., Yilmaz, O., Eser, E., Quittner, A. L. (2007) Turkish
translation and validation of revised cystic fibrosis questionnaire
(CFQ-R) for children [abstract]. Journal of Cystic Fibrosis,
11. Quittner, A. L., Buu, A., Messer, M. A., Modi, A. C., & Watrous,
M. (2005). Development and validation of the cystic fibrosis
questionnaire in the United States: A health-related quality-of-life
measure for cystic fibrosis. Chest, 128(4), 2347–2354.
12. Modi, A. C., & Quittner, A. L. (2003). Validation of a disease-
specific measure of health-related quality of life for children with
cystic fibrosis. Journal of Pediatric Psychology, 28(8), 535–546.
13. Ravens-Sieberer, U., & Bullinger, M. (1998). Assessing the
health related quality of life in chronically ill children with the
German KINDL: First psychometric and content-analytical
results. Quality of Life Research, 7(5), 399–407.
14. Erhart, M., Ellert, U., Kurth, B. M., & Ravens-Sieberer, U.
(2009). Measuring adolescents’ HRQoL via self reports and
parent proxy reports: an evaluation of the psychometric properties
of both versions of the KINDL-R instrument. Health Qual Life
Outcomes., 2009(7), 77.
15. Eser, E., Yu ¨ksel, H., Baydur, H., et al. (2008) The psychometric
properties of the new Turkish generic health-related quality of
life questionnaire for children (Kid-KINDL). Tu ¨rk Psikiyatri
Dergisi, 19(4), 409–417.
16. Quittner, A. L., Sweeny, S., Watrous, M., et al. (2000). Trans-
lation and linguistic validation of a disease-specific quality of life
measure for cystic fibrosis. Journal of Pediatric Psychology,
17. Ware, J. E., Brook, R. H., Ross Davies, A., Williams, K. N.,
Stewart, A. L., Rogers, W. H., et al. (1980). Conceptualization
and measurement of health for adults in the Health Insurance
Study. Vol. I: Model of health and methodology. Doc. no. R-1987/
1-HEW. Santa Monica, CA: RAND Corporation.
18. Bregnballe, V., Thastum, M., Lund, L. D., Hansen, C. R., Pre-
issler, T., & Schiøtz, P. O. (2008). Validation of the Danish
version of the revised cystic fibrosis quality of life questionnaire
in adolescents and adults (CFQ-R14?). Journal of Cystic
Fibrosis, 7, 531–536.
19. Schmidt, A., Wenninger, K., Niemann, N., Wahn, U., & Staab, D.
(2009). Health-related quality of life in children with cystic
fibrosis: Validation of the German CFQ-R. Health Qual Life
Outcomes, 7, 97.
414 Qual Life Res (2013) 22:409–414