Endocrine Abstracts

Sleep disordered breathing (SDB), including obstructive sleep apnoea (OSA), is associated with excessive daytime somnolence, and impacts significantly on quality of life in affected individuals. It also predisposes to premature cardiovascular (hypertension, congestive cardiac failure, myocardial infarction, sudden death, and stroke) and metabolic (diabetes mellitus and dyslipidaemia) dysfunction.

SDB is a well-recognised complication of acromegaly. In most centres, routine screening for SDB consists of an Epworth sleepiness scale (ESS)±overnight oximetry to measure desaturation index (DI). However, polysomnography remains the gold-standard investigation. Here, we present the largest study to date of SDB in newly diagnosed, treatment naïve, patients with acromegaly (n=39) using polysomnography.

OSA, defined by the apnoea–hypopnoea index (AHI), was a common finding (77%) in newly-diagnosed acromegaly: mild OSA, n=12; moderate OSA, n=5; and severe OSA, n=13. However, in contrast DI markedly underestimated the extent of sleep disordered breathing in our cohort: mild OSA, n=11; moderate OSA, n=7; and severe OSA, n=3. ESS also failed to predict the presence of SDB in many patients (ESS>11, n=12).

Consistent with the finding of a high rate of OSA, patients exhibited an increased arousal index, with marked disruption of the normal sleep cycle, despite the majority (n=33) exhibiting a normal total sleep period time. Twenty-six patients spent longer than predicted in stage 1 sleep, with reciprocal attenuation of the deeper sleep stages (reduced stage 2, n=25; reduced slow wave sleep, n=25; and reduced REM sleep, n=30).

Our findings suggest that the majority of patients with acromegaly have evidence of sleep disordered breathing, with detrimental effects on sleep architecture – in particular marked attenuation of the deeper sleep stages. Moreover, we have shown that the use of ESS and DI as primary screening for SDB in acromegaly underestimates the prevalence of sleep apnoea and may lead to failure to diagnose and treat this important complication.