Validity and Reliability of a Novel Multimodal Questionnaire for the Assessment of Abdominal Symptoms in People with Cystic Fibrosis (CFAbd-Score)

Abstract

Background and ObjectiveFor people with cystic fibrosis, validated patient-reported outcome measures for the assessment of the complex abdominal involvement are lacking. The objective of this study was to examine whether the CFAbd-Score, a novel questionnaire consisting of 28 items, meets the essential requirements (validity and reliability) for a patient-reported outcome measure according to US Food and Drug Administration recommendations. Methods Content validity was assessed by recording the frequencies and severity of symptoms that occurred during the prior 2 weeks in patients with cystic fibrosis (n = 116; aged ≥ 6 years). Comparing the CFAbd-Score results obtained from patients with cystic fibrosis and healthy controls (n = 88), we determined known-groups validity. To explore the structure of the patient-reported outcome measure, a factor analysis was conducted. Internal consistency of the five extracted score domains was assessed using Cronbach's alpha. For test-retest reliability, a subgroup of patients (n = 43) was reevaluated and intra-class correlation coefficients were determined. ResultsThe CFAbd-Score differentiated patients with cystic fibrosis from healthy controls with a large effect size (17.3 ± 1.1 vs. 8.0 ± 0.7 points; p < 0.001; Cohen's d = 0.85). Items, domains, and scores reflected the relevance to patients with cystic fibrosis and allowed a differentiation between subgroups of patients with cystic fibrosis (e.g., patients with and without abdominal pain, pancreatic sufficiency, and age groups). High item-domain loadings as well as good to excellent internal consistency and reproducibility (Cronbach's α = 0.70-0.92; intra-class correlation coefficient = 0.932, 95% confidence interval 0.874-0.963) indicated construct validity and reliability. Conclusions The CFAbd-Score has successfully passed through key steps of the iterative process of patient-reported outcome measure development. Prospectively, the CFAbd-Score is proposed as a patient-centered instrument for monitoring abdominal symptoms and, most interestingly, for evaluating changes in symptoms with novel treatments such as cystic fibrosis transmembrane regulator modulators. Trail Registration ClinicalTrials.gov: NCT03052283.

Postprandial changes in gastrointestinal function and transit in cystic fibrosis assessed by magnetic resonance imaging

“…Participants stopped taking any laxatives or anti-diarrhoeals on the day of scanning. Participants completed two symptom questionnaires, the PAC-SYM 11 and CFAbd-Score, 14 regarding symptoms during the preceding 2 weeks. They then underwent a fasting baseline set of MRI scans, followed by their first meal.…”

“…Gastrointestinal symptoms over the 2 weeks preceding the scan day were assessed using the CFAbd-Score 14 and PAC-SYM 11 questionnaires as described above. The CFAbd-Score comprises 28 items grouped into 5 domains (pain, gastro-oesophageal reflux, disorders of bowel movement, eating and appetite, impairment of quality of life) which are weighted to provide a final score.…”

“…The CFAbd-Score comprises 28 items grouped into 5 domains (pain, gastro-oesophageal reflux, disorders of bowel movement, eating and appetite, impairment of quality of life) which are weighted to provide a final score. 14 The PAC-SYM final score is determined by the total score divided by the number of items answered. 11 For both questionnaires, a lower score correlates with lower symptom burden.…”

“…12 In the United Kingdom, use of the Gastrointestinal Symptoms Rating Scale (GSRS) has identified a high symptom burden in a large proportion of patients. 13 CF-specific questionnaires such as the CFAbd-Score have also been derived and validated 14,15 . Such work can describe the prevalence and impact of symptoms but does not provide an understanding of the mechanisms by which CTFR dysfunction impacts upon gastrointestinal function.…”

Assessing gastro-intestinal related quality of life in cystic fibrosis: Validation of PedsQL GI in children and their parents

“…This newly constructed questionnaire is also very detailed and aims to represent CF-specific abdominal symptoms. Reports show correlations with findings on abdominal ultrasound [30], significant discriminative validity and low natural variability in patients older than 6 [31]. However, there are no data on comparison with existing questionnaires and data are scarce for the age group <6.…”