Sleep apnoea among Australian Aboriginal and non-Aboriginal patients in the Northern Territory of Australia—a comparative study

Abstract

Australian Aboriginal and Torres Straight Islanders (ATSI) are noted to have a higher burden of chronic health conditions. However, there is a paucity of data on obstructive sleep apnoea (OSA) in this population. In this retrospective study, we evaluated the clinical and polysomnographic (PSG) characteristics of ATSI and non-ATSI adult patients who underwent diagnostic PSG between 2011 and 2015. There were a total of 3078 patients. Of the total, 403 (13%) were of ATSI origin. Among those of ATSI origin, 61% were male and 39% females, while among the non-ATSI cohort, 66% were males. The median age was 47.8 years in ATSI and 51.5 years in the non-ATSI cohort. In the combined cohort, body mass index was more than 30 kg/m2 (61%), hypertension (14.4%), diabetes (17.8%), and heart disease (23.3%). The ATSI patients had higher rates of class III obesity (27 vs. 15%), hypertension (26 vs. 14%), cardiac disease (34 vs. 23%), and diabetes (37 vs. 17%). Among all the study participants, the PSG confirmed 83.7% of the patients had an apnoea–hypopnea index (AHI) more than 5/h, mild (AHI 5–15/h) in 28.4%, moderate (AHI 15–30/h) in 22.3%, and severe (AHI > 30/h) in 33.0%. Among the ATSI patients, 46% had severe OSA. The median total AHI value was higher in the ATSI population (25, interquartile range [IQR]: 11–58) compared to the non-ATSI (17, IQR: 7–36), and in rural/remote population (19, IQR: 8–42) compared to urban (17, IQR: 7–37). This trend was similar for NREM (non-rapid eye movement)-AHI and REM (rapid eye movement)-AHI scores, although statistically significant difference was found only with ATSI status. In the combined cohort the probability of (OR = 1.62, 95% CI: 1.32–2.00, p < 0.001) of severe OSA was 62% higher in individual with hypertension, however, when stratified by ATSI status, the association was only significant in the non-ATSI population (OR = 1.53 95% CI: 1.21–1.94, p < 0.001). The odds of severe AHI was also significantly associated with heart disease (1.37; 95% CI: 1.14,1.63, p < 0.001), diabetes (1.74; 95% CI: 1.43,2.10; p < 0.001) and smoking (1.28; 95% CI: 1.09,1.50, p = 0.0023) in the overall study cohort. In both ATSI and non-ATSI patients, body mass index, neck circumference, sleep efficiency, wake after sleep onset, and respiratory arousal index were significantly higher and independently associated with severe AHI.

Is sleep duration associated with overweight/obesity in Indigenous Australian adults?

“…Similar data from Central Australia and far north Queensland reported that compared with non-Indigenous people, Indigenous people diagnosed with OSA were more likely to be female, live in remote communities and be obese [54]. This is an area for further research given the prevalence of obesity in Indigenous communities and the associated risk of OSA with adverse health outcomes and increased all-cause mortality [53].…”

“…Two reports have since added to the Australian Indigenous context. A retrospective analysis of diagnostic sleep test data from the Northern Territory found that severe sleep apnoea was associated with male gender, increasing age, higher body weight, and Indigenous status [53]. Similar data from Central Australia and far north Queensland reported that compared with non-Indigenous people, Indigenous people diagnosed with OSA were more likely to be female, live in remote communities and be obese [54].…”

<p>Gender Differences in the Clinical and Polysomnographic Characteristics Among Australian Aboriginal Patients with Obstructive Sleep Apnea</p>

“…The study participants who self-identified as only of Australian Aboriginals aged 18 years and over from our previous study cohort 28 were included in this study. Patients who identified to be of both Aboriginal and/or Torres Strait Islander origin (ATSI) or Torres Strait Islander origin alone (TSI) were excluded from the study, in order for this study to represent a uniquely defined Australian Aboriginal cohort with similar genetic/ethnic, cultural pool, exposed to similar environmental and living conditions.…”

“…The sleep studies which were performed and analysed during this study period were according to the 2007 American Academy of Sleep Medicine recommendations and as described in the previous study. 28 All failed sleep studies, type 3, type 4 (limited sleep studies), continuous positive airway pressure (CPAP) initiation/titration studies, and studies in which AHI or sleep architecture was not available were excluded.…”

“…[24][25][26][27] A recent study from our center had demonstrated that a higher proportion of ATSI patients were noted to have severe OSA. 28 Although there is growing evidence to suggest that OSA manifests differently in different ethnic populations and has gender differences; however, there is limited evidence in the literature with regards to the ethnic and gender influence among Australian or other Indigenous/Aboriginal populations. Hence, it would be more meaningful to study a homogenous NT Australian Aboriginal cohort with a similar genetic/ethnic pool exposed to similar environmental and cultural conditions.…”