Dissertation committee:
Μελέτιος Α. Δημόπουλος, Καθηγητής, Ιατρική Σχολή ΕΚΠΑ,
Δικαίος Δημήτριος, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Βασιλακόπουλος Θεόδωρος, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Τσαγκάρης Ηρακλής, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Τρακαδά Γεωργία, Αν. Καθηγήτρια Ιατρικής Σχολής ΕΚΠΑ
Σταματελλόπουλος Κίμων, Αν.Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Μανιός Ευστάθιος, Αν. Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Summary:
Introduction: There is a lack of evidence in the general population concerning sleep disturbances in the Greek population and in Southern Europe in general. The study was originally designed to estimate the prevalence of Obstructive Sleep Apnea Syndrome in Cyprus and to evaluate different relative factors especially symptoms and comorbidities. The thesis extended the research to approach the epidemiology of other sleep disorders such as insomnia and circadian rhythm sleep-wake disorders in the general population. Alongside it presented the sleep characteristics of the Mediterranean population of Cyprus and the quality of sleep.
Aim: The aim of our study was to assess the prevalence of Obstructive Sleep Apnea (OSA), insomnia and circadian rhythm sleep-wake disorders in the general population of Cyprus, the southeast part of Europe, and to avoid a significant limitation of previous studies conducted in the sleep laboratory setting and with preselected patients. Moreover, to evaluate sleep quality and contributing factors and outline sleep characteristics in Cyprus.
Subjects and methods: The survey was contacted by CATI method (Computed Aided Telephone Interviewing). The selection of the participants was performed randomly by the phone book. The interview was then contacted by phone. Participants were all adults, age 18+ residing in Cyprus. The sample was stratified according to the last demographic report (2016) by district, rural or urban area, gender and age (1). Stratification ensures that the sample is representative of the population with respect to the chosen population parameters (2). The estimated sample size needed was 2000 but 5736 sample housing units were screened for eligible adults and 4118 eligible responders completed the survey by answering STOP-BANG questionnaire.
In the second stage of the survey, 400 candidates from the initial stratified sample, 200 with low probability for OSA and 200 with medium/high probability for OSA were randomly selected to further participate in a clinical assessment using questionnaires, sleep diary and sleep study Type III. The respond rate for the questionnaires completion was 86,5% (348) and 283 (70,8% of the 400) underwent a sleep study.
Results: From a sample of 4118 participants (2252 male-54.7%, 1862 female-45.3%), 46.6% were over 50 years old, 2641 (64.1%) were classified as low risk for OSA (0-2 positive answers), 1200 (29.1%) as intermediate risk (3-4 positive answers) and 277 (6.7%) as high risk (≥5 positive answers).
During the verification phase, 14,29% (6/42) of the younger age participants (18-39 years), 29.69% (38/128) from the middle aged (40-59 years) and 41,96% (47/112) of the third age group (≥60 ετών) had ΑΗΙ≥15. Συνολικά 32,27% (91/282) είχαν ΑΗΙ≥15. Extrapolating the results to the studied population, taking into consideration the percentage of each age group (42%, 29%, 29% respectively), the OSA prevalence is estimated to 26,78%. Female had ΑΗΙ≥15 24,72% (22/89) and male 35,75% (69/193). From patients with ΑΗΙ≥15/ώρα, 57,14% (52/91) reported snoring and 29,57% (55/186) of those with ΑΗΙ<15/ώρα.
Hypertension was related to all sleep study indices, namely: REI>5 (P<0.001), REI >15 (p 0.004), ODI>15 (p 0.002), mSaO2 (p<0.001) and TST90 (p 0.019). Arrhythmias were related to mSaO2 (p 0.001) and TST90 (p 0.0040). Heard failure was associated with REI (p 0.043), especially in the supine position (p 0.036). The cutoff point was 14.25 respiratory events per hour.
The symptomatic group (with insomnia and/or excessive daytime sleepiness) reported poor sleep quality, and increased symptoms of anxiety, depression and fatigue. The global PSQI score in the symptomatic group was primarily affected by sleep disturbances, sleep duration and subjective sleep quality while in the asymptomatic group the determines were sleep duration and sleep disturbances. Symptomatic had poorer sleep quality when compared to the asymptomatic group (GR-PSQI, 8.41±4.23, vs 4.88±2.43, p=0.000). The frequency and magnitude of anxiety and depression were graver in the symptomatic (anxiety 18.1% vs 2.9% p 0.003, depression 12% vs 2.9% p 0.037). Symptomatic were more anxious (6.55±4.37 vs 3.65±3.01, p=0.000) and more depressed (6.08±3.81 vs 3.26±3.28, p=0.000) compared to asymptomatic according to HADS.
Insomnia was estimated during the second phase of the study by using Athens Insomnia Index. From the 264 collected questionnaires 40,5% were rated >6. The mean scale value was 6,33±4,43.
From 195 participants, 128 males– 65.6% and 67 females– 34.4%, 25 fulfilled the criteria for CRSWD (12.8%). The most prominent were Delayed sleep-wake phase disorder, DSWPD (10 individuals, 5.1%) Shift Work Sleep Disorder, SWD (13 individuals, 6.7%). Less common were Irregular sleep-wake rhythm disorder, ISWRD (1,0.5%) and Advanced sleep-wake phase disorder, ASWPD (1,0.5%). Patients were middle aged (49.64±13.87), and without gender differences.
Conclusion: According to our data, the estimated prevalence of intermediate to high risk for OSA is 50% in male and 18% in female and in the follow up study 32,27% had ΑΗΙ≥15.Thiw findings are comparable to other recent epidemiological studies.
Sleep study indices are independently associated with specific cardiovascular disorders suggesting different pathophysiological pathways contribute unevenly in their etiology.
The symptomatic OSA phenotype presents with compromised sleep quality leading to a vicious circle of anxiety and depression.
Insomnia is classified as the most prevailing sleep disorder, presenting in 40,5% of Cyprus population.
According to our data, CRSWDs are common in the general population of Cyprus, especially DSWPD and SWD. Affected individuals suffer from sleep deprivation and usually complain about insomnia, sleepiness and depression. Sleep quality is optimum for half of the population and sleep deprivation and sleep disturbances are the most decisive sleep quality coefficients.
