Table 2

Summary of subject characteristics of included studies

Trial Mean
(SD or range)
age (years)
Severity of asthma Concurrent medication Severity of gastro-oesophageal reflux Symptomatic gastrooesophageal reflux (%) Association between gastro-oesophageal reflux and asthma reported
Ekstrom19 58.5 (28–70)ATSModerate or severe20/48 OCS; antacids allowedSymptoms of heartburn and/or acid regurgitation 48/48; abnormal pH 32/48100%Yes (27/50)
Ford20 63 (50–80)DRBaseline PEF 253–300 l/minICS 8/10; antacids allowedOesophagitis: grade I (n=1); grade II (n=1); grade III (n=3); Barrett's oesophagus (n=2)100%No
Goodall21 54 (30–65)DRNocturnal wheezing, improvement in FEV1>20% in 11/20 subjects ICS or OCS 15/16Oesophagitis 11/20; abnormal pH 8/18; decreased LESP 8/20; heartburn 19/20; regurgitation 12/2095% Yes (10/18)
Gustaffson 22 14.2 (10–20)DRNot statedSCG 23/37; ICS 12/37; Iβ2A 19/37; Oral Theo 25/37; OCS 2/37Mean (SE) % time pH <4 = 0.5 (0.1); 2.7 (0.3)49%No
Kjellen23 52 (36–65)ATSDescribed as more severe asthma2A 52/61; ICS 18/61; OCS 13/61; Theo 8/61Hiatial hernia 55%; dysmotility 58%; abnormal pH 35%; decreased LESP 40%Not reportedNo
Larrain24 44 (11)DR56/81 reactive airwaysAntacids allowed; OCS or ICS 38/90; Theo: number not specifiedOesophagitis: grade 1 (n=20/81); normal (n=60/81). Free reflux on radiography after loading stomach with 300 ml acid (n=38/81)74%No
Meier25 49 (34–63)ATSNot reported; inclusion criteria required >15% reversibility (FEV1 and PEF)Asthma medications continued as usual; type of medications not specifiedOesophagitis 15/15: grade I (n=1); grade II (n=4); grade III (n= 8); grade IV (n=2); stricture (n=8/15); Barrett's oesophaus (n=2/15); hiatal hernia (n=10/15)100%Yes (proportion
not reported)
Nagel26 42 (20–64)DRNot reported; inclusion criteria required >25% reversibility (FEV1 and PEF)Usual medications continued; type not specifiedAbnormal 24 hour pH monitoring100%Yes (15/15)
Teichtahl27 46 (12)DRNot reported; inclusion criteria required >15% reversibility (FEV1) and diurnal variation of PEF of ⩾20% in PEF in past 6 monthsSCG and Oβ2A not allowed; Iβ2A allowed as required; other asthma medications continued as usualGrade 0 (n=3); grade I (n=4); grade II (n=11); grade III (n=2). Mean % of time pH <4 = 12.2%95%No
Boeree28 51 (10)ATSModerate to severeICS >0.4 mg/dayMild symptoms, abnormal pH in all 50%No
Levin29 57 (35–72)ATSNot stated2A in allAbnormal pH in all100%No
Kiljander30 49 (21–75)ATSMild to moderate2A 91%; ICS 89%Abnormal pH in all 65%No
  • ATS = diagnosis for asthma made in accordance with American Thoracic Society guidelines; DR = asthma diagnosis made in accordance with a doctor's diagnosis; LESP = lower oesophageal sphincter pressure; SCG = sodium cromoglycate; ICS=inhaled corticosteroids; OCS= oral corticosteroids; Iβ2A = inhaled β2agonists; Oβ2A = oral β2 agonists; Theo = theophylline; PEF = peak expiratory flow.