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Aim: To study if individuals with nocturnal gastroesophageal reflux (nGER) and habitual snoring are more likely to develop asthma and respiratory symptoms (i.e. wheeze, cough, chest tightness, breathlessness) than those without these conditions, and if these associations are additive.

Methods: We used data from the population-based prospective questionnaire study Respiratory Health in Northern Europe (RHINE) (11,024 participants), with data from 1999 and 2011. Participants with heartburn or belching after going to bed, at least 1 night/week, were considered to have nGER. Participants reporting loud snoring at least 3 nights/week were considered to have habitual snoring. Participants were grouped into four groups by their nGER and snoring status: “never”; “former”; “incident”; “persistent”. Incident respiratory symptoms were analyzed among participants without respective symptom at baseline.

Results: Snoring and nGER were independently associated with incident asthma and respiratory symptoms. The risk of incident wheeze was increased in subjects with incident or persistent snoring (adjusted odds ratio (95 % CI): 1.44 (1.21–1.72)), nGER (2.18 (1.60–2.98)) and in those with both snoring and nGER (2.59 (1.83–3.65)). The risk of developing asthma was increased in subjects with incident or persistent snoring (1.44 (1.15–1.82)), nGER (1.99 (1.35–2.93)) and in those with both snoring and nGER (1.72 (1.06–2.77)). No significant interaction was found between snoring and nGER. A similar pattern was found for the incidence of all other respiratory symptoms studied, with the highest risk among those with both incident or persistent nGER and snoring.

Conclusion: The risk of developing asthma and respiratory symptoms is increased among subjects with nGER and habitual snoring. These associations are independent of each other and confounding factors. Snoring and nGER together are additive on respiratory symptoms.