Obstructive sleep apnea and multimorbidity

Robichaud-Hallé et al. BMC Pulmonary Medicine 2012, 12:60 http://www.biomedcentral.com/1471-2466/12/60 RESEARCH ARTICLE Open Access Obstructive sleep apnea and multimorbidity Laurence Robichaud-Hallé1, Michel Beaudry2 and Martin Fortin2,3* Abstract Background: Obstructive sleep apnea (OSA) is becoming increasingly prevalent in North America and has been described in association with specific chronic diseases, particularly cardiovascular diseases. In primary care, where the prevalence of co-occurring chronic conditions is very high, the potential association with OSA is unknown. The purpose of this study was to explore the association between OSA and 1) the presence and severity of multimorbidity (multiple co-occurring chronic conditions), and 2) subcategories of multimorbidity. Methods: A cluster sampling technique was used to recruit 120 patients presenting with OSA of various severities from the records of a sleep laboratory in 2008. Severity of OSA was based on the results of the polysomnography. Patients invited to participate received a mail questionnaire including questions on sociodemographic characteristics and the Disease Burden Morbidity Assessment (DBMA). They also consented to give access to their medical records. The DBMA was used to provide an overall multimorbidity score and sub-score of diseases affecting various systems. Results: Bivariate analysis did not demonstrate an association between OSA and multimorbidity (r = 0.117; p = 0.205). However, severe OSA was associated with multimorbidity (adjusted odds ratio = 7.33 [1.67-32.23], p = 0.05). OSA was moderately correlated with vascular (r = 0.26, p = 0.01) and metabolic syndrome (r = 0.26, p = 0.01) multimorbidity sub-scores. Conclusions: This study showed that severe OSA is associated with severe multimorbidity and sub-scores of multimorbidity. These results do not allow any causal inference. More research is required to confirm these associations. However, primary care providers should be aware of these potential associations and investigate OSA when deemed appropriate. Keywords: Obstructive sleep apnea, Multimorbidity, Disease Burden Morbidity Assessment, Chronic disease, Severity Background Millions of North Americans are affected by the consequences of sleep disorders. Among these disorders, sleep apnea syndrome has the highest rate of mortality and morbidity [1]. According to the Public Health Agency of Canada, 858,900 Canadians reported suffering from sleep apnea, and almost 26% of Canadians are at high risk of developing the condition [2]. This disorder poses a major public health problem due to its prevalence, severity and socioeconomic burden. Obstructive sleep apnea (OSA) is defined as the cessation of naso-buccal air flow for more than 10 seconds [3], and is diagnosed * Correspondence: 2 Centre de santé et de services sociaux de Chicoutimi, Saguenay, Québec, Canada 3 Département de médecine de famille, Université de Sherbrooke, 305, St-Vallier, Chicoutimi, Québec G7H 5H6, Canada Full list of author information is available at the end of the article based on an apnea–hypopnea index (AHI) value greater than five per hour of sleep [4], usually accompanied by a 4% decrease in oxygen saturation [4]. It is estimated that 80% of obstructive sleep apnea cases remain undiagnosed [5], making it difficult to identify patients at risk of associated comorbidities [6]. Reuveni et al. suggest that programs be developed to increase the level of suspicion of OSA among primary care providers [7]. OSA syndrome is independently associated with an increased risk of mortality [8,9]. Fletcher [10] reported that 70% to 90% of patients with OSA have hypertension [10]. Associations between OSA and heart failure [11], OSA and arrhythmias [12], OSA and diabetes [13], OSA and insulin resistance [14] and OSA and metabolic syndrome [15] have also been reported. Successful treatment of OSA helps to better control many of the associated diseases and chronic conditions [11,16-18]. Men, people 40 years old and over, and those with a high © 2012 Robichaud-Hallé et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Robichaud-Hallé et al. BMC Pulmonary Medicine 2012, 12:60 http://www.biomedcentral.com/1471-2466/12/60 body mass index (BMI) or a large neck circumference are at greater risk for OSA [19-21]. Multimorbidity—the co-occurrence of two or more chronic diseases—is an emerging concept in the medical literature [22]. One study showed that nine out of ten primary care patients had more than one chronic condition, while approximately 50% had five or more [23]. Multimorbidity has been associated with several adverse effects, such as a reduction in quality of life [24,25], an increase in psychological distress [26], medical complications and increased mortality [27]. Evidence of an association between OSA and multimorbidity could be an important incentive for the systematic screening for OSA in primary care settings— where the prevalence of multimorbidity is very high. The first objective of this study was to measure the association between the severity of OSA and the severity of multimorbidity, and second, to explore the association between OSA and various categories of multimorbidity. Methods This study used data from the sleep laboratory of the Centre de santé et de services sociaux de Chicoutimi (CSSSC), a regional health centre in the Saguenay region of Québec (Canada). As a first step in the recruitment process, a list of patients who had undergone polysomnography in 2008 was compiled. Patients were categorized according to the severity of their OSA, based on their polysomnography results (absent: AHI 0-4; mild: AHI 5-14; moderate: AHI 15-29; severe: AHI ≥ 30). We selected consecutive patients from each category to ensure a proportional representation (25% each) of the four OSA categories. French-speaking patients were selected between 30 and 75 years of age, to ensure adequate variation in degrees of multimorbidity. Each patient underwent polysomnography after January 1, 2008, either in the sleep laboratory as a full night or a split-night study: the first half of the night is used to obtain a diagnosis, the second half is used to perform continuous positive airway pressure (CPAP) titration (level I), or, at home as an outpatient (level II). Patients with a diagnosis of upper airway resistance were excluded from the study, as were people who slept less than three hours a night and those referred for a diagnosis other than apnea, such as parasomnia. After providing informed consent, participants selected at this stage received a questionnaire covering multimorbidity and socio-demographic variables. Data related to variables of the evaluation conducted at th (...truncated)