Symptom overlap in patients with upper gastrointestinal complaints in the Canadian confirmatory acid suppression test (CAST) study: further psychometric validation of the reflux disease questionnaire.
BACKGROUND
The reflux disease questionnaire (RDQ) is a short, patient-completed instrument.


OBJECTIVE
To investigate the psychometric characteristics of the RDQ in patients with heartburn-predominant (HB) and non-heartburn predominant (NHB) dyspepsia.


METHODS
HB (n = 388) and NHB (n = 733) patients were randomized to esomeprazole 40 mg daily or twice daily for 1 week, followed by 3 weeks of esomeprazole 40 mg daily.


RESULTS
High factor loadings (0.78-0.86) supported the 'regurgitation' dimension of the RDQ. Overlapping factor loadings in the 'heartburn' and 'dyspepsia' dimensions suggested symptom overlap. All dimensions demonstrated high internal consistency (Cronbach's alpha: 0.79-0.90). Intra-class correlation coefficients over 4 weeks were good (0.66-0.85). The RDQ showed good responsiveness over 4 weeks of treatment, with high effect sizes (> or =0.80). Moderate or large symptom improvements were reported by 90% and 77% of HB and NHB patients, respectively, following treatment. Patients who responded to acid suppression also experienced symptom benefits in all RDQ dimensions.


CONCLUSIONS
The RDQ is reliable, valid and responsive to change in HB and NHB patients. The symptom overlap is important but need not play a major role in determining treatment strategy as both patient groups benefited from proton pump inhibitor treatment.
van Zanten
S V
SV
Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, AB, Canada. vanzanten@ualberta.ca
Armstrong
D
D
Barkun
A
A
Junghard
O
O
White
R J
RJ
Wiklund
I K
IK
D000328:Adult; D000897:Anti-Ulcer Agents / Q000627:therapeutic use*; D002170:Canada; D004415:Dyspepsia / Q000188:drug therapy*; D064098:Esomeprazole / Q000627:therapeutic use*; D005744:Gastric Acid / Q000378:metabolism; D005764:Gastroesophageal Reflux / Q000188:drug therapy*; D006356:Heartburn / Q000188:drug therapy*; D006801:Humans; D008297:Male; D011594:Psychometrics; D011795:Surveys and Questionnaires / Q000592:standards*
D000897:Anti-Ulcer Agents; D064098:Esomeprazole