Bidirectional Association Between GERD and Asthma: Two Longitudinal Follow-Up Studies Using a National Sample Cohort.

Abstract

A relation between gastroesophageal reflux disease (GERD) and asthma has been suggested; however, causality has not been investigated. This study aimed to delineate the causal relation between GERD and asthma. Participants of the Korean National Health Insurance Service-National Sample Cohort 2002-2013 who were ≥20 years old were selected for this study. In study I, 116,502 patients with GERD were matched in a 1:2 ratio to 233,004 control I participants, and the hazard ratio (HR) of asthma in patients with GERD was analyzed. In study II, 104,146 patients with asthma were matched in a 1:1 ratio to 104,146 control II participants, and the HR for GERD in patients with asthma was analyzed. A stratified Cox-proportional hazards model was used. Subgroup analyses were performed according to age and sex. In study I, 12.5% (14,595 of 116,502) of the GERD group and 7.8% (18,135 of 233,004) of the control I group presented asthma (P < .001). The GERD group demonstrated a 1.46-fold higher HR for asthma than the control I group (95% confidence interval [CI] = 1.42-1.49, P < .001). In study II, 16.9% (17,582 of 104,146) of the asthma group and 11.9% (12,393 of 104,146) of the control II group presented GERD (P < .001). The asthma group showed a 1.36-fold higher HR for GERD than the control II group (95% CI = 1.33-1.39, P < .001). All age and sex subgroups presented consistent results. GERD and asthma had a bidirectional relation in the study population.