Table 1. Prevalence of GERD symptoms in asthmatic patients.

GERD: gastroesophageal reflux disease

Reference	Year	Design	Population	Method	Results
Shirai et al. [38]	2015	Cross-sectional study	N = 132 patients with controlled asthma	Questionnaires	Among the 132 subjects with controlled asthma, it was determined that 29 patients (22.0%) had GERD
Bohr et al. [35]	2010	Cross-sectional study	Asthmatics: N = 308; controls: N = 694	Questionnaires	GERD was present in 25.4% of asthmatics vs. 19.4% of controls. Occasional symptoms of GERD present in 21.2% of asthmatics vs. 27.0% of controls
Havemann et al. [12]	2007	Systematic review	28 epidemiological studies	Description of GERD symptoms, severity, frequency, and 24-hour pH-monitoring	The average prevalence of GERD symptoms was 59.2%, compared to 38.1% in controls
Gislason et al. [37]	2002	Cross-sectional study	Total population: N = 2661	Questionnaires and detailed interviews	Asthmatics (n=459) had nocturnal GERD and esophagitis in 40% of cases vs. random population sample (n=101) 4.6% of cases
Field et al. [36]	1996	Cross-sectional study	Asthmatics: N = 109; control groups: N = 68, N = 67	Questionnaires	Among the asthmatics, 77% had heartburn, 55% had regurgitations, and 24% had difficulty swallowing