Validation of a survey methodology for gastroesophageal reflux disease in China

BMC Gastroenterology

Table 3 Reliability of questionnaires.

Questionnaire	Number of items	Test-retest reliability coefficient*	Cronbach's alpha coefficient
RDQ	12	0.80	0.86
GERD Impact Scale	8	0.71	0.80
QOLRAD	25	0.93	0.98
SF-36	36	0.96	0.90

*Cohen's kappa coefficient for the RDQ, GERD Impact Scale and QOLRAD; intraclass correlation coefficient for SF-36. GERD: gastroesophageal reflux disease; RDQ: Reflux Disease Questionnaire; QOLRAD: Quality of Life in Reflux and Dyspepsia questionnaire; SF-36: 36-Item Short-Form Health Survey.

ISSN: 1471-230X