Nocturnal asthma-like symptoms (NAS) such as tightness in the chest and shortness of breath are often perceived as asthma but could in fact be obstructive sleep apnoea (OSA).
A study of almost 800 middle-aged participants in the Tasmanian Longitudinal Cohort Study, ascertained OSA risk via the STOP-Bang questionnaire and assessed lung function in the lab.
It found FEV1/FVC ratio was significantly lower in participants with current asthma and no nocturnal symptoms than in those with NAS regardless of current asthma status.
“Both OSA risk and likelihood of more severe OSA were associated with increased risk of NAS regardless of current asthma status but were not associated with current asthma without NAS,” the study authors wrote in Respirology.
Bronchial hypersensitivity (BHR) was strongly associated with current asthma with and without NAS.
“However in the absence of current asthma there was no evidence of an association between bronchial hypersensitivity and NAS,” they said.
The study authors noted that 14.7% of study participants who reported nocturnal symptoms did not report current asthma yet they had woken due to tightness in the chest, shortness of breath or ‘asthma’ but not had attacks of asthma, wheezing, whistling in the chest, or taken medication for asthma.
“This indicates a greater likelihood of their nocturnal symptoms being unrelated to asthma,” the study authors said.
“There could be a subset of patients where OSA is worsening asthma control, including in daytime. In addition, some of ‘nocturnal asthma’ in those with OSA could be OSA symptoms that respond to OSA treatment.”
“Ideally, patients with NAS who have other clinical features that predispose to OSA should be screened for potentially undiagnosed OSA, in addition to optimising asthma management for those who have ongoing symptoms attributable to asthma.”
They suggested future research using overnight polysomnography rather a validated scoring system to assess OSA risk was required to better understand the associations between OSA and asthma symptoms.