Polysomnographic variables in Alternate overlap syndrome: data from sleep heart health study.

Objective: To evaluate influence of asthma on polysomnographic variables of patients with obstructive sleep apnea (OSA).Methods: A longitudinal retrospective study using data collected from the Sleep Heart Health Study (SHHS).Results: All 2822 patients included had OSA, 2599 were non-asthmatic whereas 223 were asthmatics. Average BMI for non-asthmatics was 28.8 kg/m2 whereas asthmatics had 29.5 kg/m2. Median pack-years of smoking was 1.42 vs. 1.98 in non-asthmatic and asthmatic groups, respectively. Sex distribution, age (in years), BMI, FEV1, FVC, AHI ≥ 4% (all apneas, hypopneas with ≥4% oxygen desaturation or arousal per hour of sleep), RDI ≥ 3% (overall respiratory distribution index at ≥3% oxygen desaturation or arousal), sleep latency, percentage of sleep time in apnea/hypopnea and Epworth sleep scale score were all statistically significant. Non-asthmatics had greater AHI (12.63/hr) compared to asthmatics (11.34/hour), p = 0.0015. RDI in non-asthmatics and asthmatics was (23.07 vs 20.53; p = 0.009). Sleep latency was found to be longer in asthmatics 19.8 minutes vs. 16 minutes (p = 0.008). Epworth sleepiness scale score was high in asthmatics (9 vs. 8, p = 0.002).Conclusion: OSA was found more severe in non-asthmatic subgroup, but asthmatics had statistically significant higher Epworth sleepiness scale score and sleep latency. Clinicians should be vigilant and keep low threshold to rule out OSA particularly on patients with difficult to control asthma, smoker, GERD, obese and nasal disease.