SAN ANTONIO – Patients with obstructive sleep apnea who complain of feeling tired when they wake up, being sleepy during the day, and have a high score on the Epworth Sleepiness Scale face an increased risk for cardiovascular disease, results from a population-based analysis suggest.
“OSA is a highly heterogeneous disease, with multiple clinical presentations and consequences,” the study’s first author,, said at the annual meeting of the Associated Professional Sleep Societies. “These patients also have diverse comorbidities, and there are arbitrary severity definitions and variable therapeutic responses. It’s difficult to lump these patients together.”
Symptom subtypes of OSA were originally described in the Icelandic Sleep Apnea Cohort, and defined as excessively sleepy, minimally symptomatic, and disturbed sleep (). These distinct clusters were identified based on symptom experiences and the existence of major comorbidities. “This concept is more popular today, trying to identify symptom clusters, or groups of individuals, that share similar polysomnographic data, and then compare differences in prevalence or incidence of cardiovascular disease,” said Dr. Mazzotti, a research associate at the University of Pennsylvania, Philadelphia. “That’s a concept that needs to be moving forward.”
Dr. Mazzotti and colleagues set out to determine if OSA symptom subtypes are present in the Sleep Heart Health, a multicenter, prospective, community-based cohort of individuals aged 40 years and older designed to assess the cardiovascular (CV) consequences of OSA. They also wanted to know if there is additional evidence of the relevance of OSA symptom subtypes, particularly with respect to cardiovascular disease .
Participant-reported symptoms, such as difficulty falling and staying asleep, snoring, fatigue, drowsy driving and daytime sleepiness, and responses to the Epworth Sleepiness Scale were used to determine the patient’s subtype. Assessments including questionnaires and in-home polysomnography were conducted at baseline (between 1995 and 1998) and follow-up (between 2001 and 2003), while CV outcomes were assessed until the end of follow-up (between 2008 and 2011).
In all, 1,207 patients from the Sleep Heart Health Study met criteria for moderate to severe OSA (apnea-hypopnea index, or AHI, of 15 or greater) and were included in the final analysis. They were followed for a mean of 12 years. Based on the clustering of symptoms, the researchers identified four OSA symptom subtypes: disturbed sleep (12%), minimally symptomatic (33%), excessively sleepy (17%), and moderately sleepy (38%) – proportions that were similar to those observed in prior studies.
The disturbed sleep subtype presented with increased prevalence of “insomnialike” symptoms, such as difficulty initiating or maintaining sleep, according to Dr. Mazzotti. “On the other hand, the excessively sleepy subtype presented with a very high prevalence of several symptoms related to excessive daytime sleepiness, while the moderately sleepy showed a moderately high prevalence of such symptoms, but not as much when compared to the excessively sleepy subtype,” he explained. “Finally, the minimally symptomatic subtype was found to have the lowest prevalence of all investigated symptoms, suggesting that these patients have low symptom burden. They do not complain as much, even though they have moderate-to-severe OSA.”
Next, Dr. Mazzotti and colleagues used Kaplan-Meier survival analysis and Cox proportional hazards models to evaluate whether subtypes were associated with incident coronary heart disease (CHD), heart failure, and CV disease, including CV mortality. Similar analyses were performed comparing each symptom subtype with 2,830 individuals without OSA (AHI less than 5).
Compared with other subtypes, the excessively sleepy group had a more than threefold increased odds of prevalent heart failure, after adjustment for other CV risk factors. They also had a 1.7- to 2.3-fold increased risk for incident CV disease (P less than .001), CHD (P = .015) and heart failure (P = 0.018), after adjustment for other CV risk factors.
“Compared to individuals without OSA, the excessively sleepy subtype is the only subtype with increased risk of incident CV disease and CHD,” Dr. Mazzotti said. “It is possible that excessively sleepy OSA patients are more likely to benefit from CPAP therapy in preventing CV disease.” These results were published online earlier this year (Am J Respir Crit Care Med. 2019 Feb 15.).
Dr. Mazzotti reported having no financial disclosures.
SOURCE: Mazzotti D et al. SLEEP 2019, .