Helena Marti-Soler

Prevalence of sleep-disordered breathing in the general population: the HypnoLaus study

BACKGROUND Sleep-disordered breathing is associated with major morbidity and mortality. However, its prevalence has mainly been selectively studied in populations at risk for sleep-disordered breathing or cardiovascular diseases. Taking into account improvements in recording techniques and new criteria used to define respiratory events, we aimed to assess the prevalence of sleep-disordered breathing and associated clinical features in a large population-based sample. METHODS Between Sept 1, 2009, and June 30, 2013, we did a population-based study (HypnoLaus) in Lausanne, Switzerland. We invited a cohort of 3043 consecutive participants of the CoLaus/PsyCoLaus study to take part. Polysomnography data from 2121 people were included in the final analysis. 1024 (48%) participants were men, with a median age of 57 years (IQR 49-68, range 40-85) and mean body-mass index (BMI) of 25·6 kg/m(2) (SD 4·1). Participants underwent complete polysomnographic recordings at home and had extensive phenotyping for diabetes, hypertension, metabolic syndrome, and depression. The primary outcome was prevalence of sleep-disordered breathing, assessed by the apnoea-hypopnoea index. FINDINGS The median apnoea-hypopnoea index was 6·9 events per h (IQR 2·7-14·1) in women and 14·9 per h (7·2-27·1) in men. The prevalence of moderate-to-severe sleep-disordered breathing (≥15 events per h) was 23·4% (95% CI 20·9-26·0) in women and 49·7% (46·6-52·8) in men. After multivariable adjustment, the upper quartile for the apnoea-hypopnoea index (>20·6 events per h) was associated independently with the presence of hypertension (odds ratio 1·60, 95% CI 1·14-2·26; p=0·0292 for trend across severity quartiles), diabetes (2·00, 1·05-3·99; p=0·0467), metabolic syndrome (2·80, 1·86-4·29; p<0·0001), and depression (1·92, 1·01-3·64; p=0·0292). INTERPRETATION The high prevalence of sleep-disordered breathing recorded in our population-based sample might be attributable to the increased sensitivity of current recording techniques and scoring criteria. These results suggest that sleep-disordered breathing is highly prevalent, with important public health outcomes, and that the definition of the disorder should be revised. FUNDING Faculty of Biology and Medicine of Lausanne, Lausanne University Hospital, Swiss National Science Foundation, Leenaards Foundation, GlaxoSmithKline, Ligue Pulmonaire Vaudoise.

Seasonality of cardiovascular risk factors: an analysis including over 230 000 participants in 15 countries

Objective To assess the seasonality of cardiovascular risk factors (CVRF) in a large set of population-based studies. Methods Cross-sectional data from 24 population-based studies from 15 countries, with a total sample size of 237 979 subjects. CVRFs included Body Mass Index (BMI) and waist circumference; systolic (SBP) and diastolic (DBP) blood pressure; total, high (HDL) and low (LDL) density lipoprotein cholesterol; triglycerides and glucose levels. Within each study, all data were adjusted for age, gender and current smoking. For blood pressure, lipids and glucose levels, further adjustments on BMI and drug treatment were performed. Results In the Northern and Southern Hemispheres, CVRFs levels tended to be higher in winter and lower in summer months. These patterns were observed for most studies. In the Northern Hemisphere, the estimated seasonal variations were 0.26 kg/m2 for BMI, 0.6 cm for waist circumference, 2.9 mm Hg for SBP, 1.4 mm Hg for DBP, 0.02 mmol/L for triglycerides, 0.10 mmol/L for total cholesterol, 0.01 mmol/L for HDL cholesterol, 0.11 mmol/L for LDL cholesterol, and 0.07 mmol/L for glycaemia. Similar results were obtained when the analysis was restricted to studies collecting fasting blood samples. Similar seasonal variations were found for most CVRFs in the Southern Hemisphere, with the exception of waist circumference, HDL, and LDL cholesterol. Conclusions CVRFs show a seasonal pattern characterised by higher levels in winter, and lower levels in summer. This pattern could contribute to the seasonality of CV mortality.

The NoSAS score for screening of sleep-disordered breathing: a derivation and validation study

BACKGROUND Diagnosis of sleep-disordered breathing requires overnight recordings, such as polygraphy or polysomnography. Considering the cost and low availability of these procedures, preselection of patients at high risk is recommended. We aimed to develop a screening tool allowing identification of individuals at risk of sleep-disordered breathing. METHODS We used the participants from the population-based HypnoLaus cohort in Lausanne, Switzerland, who had a clinical assessment and polysomnography at home, to build a clinical score (the NoSAS score) using multiple factor analysis and logistic regression to identify people likely to have clinically significant sleep-disordered breathing. The NoSAS score was externally validated in an independent sleep cohort (EPISONO). We compared its performance to existing screening scores (STOP-Bang and Berlin scores). FINDINGS We used the 2121 participants from the HypnoLaus cohort who were assessed between Sept 1, 2009, and June 30, 2013. The NoSAS score, which ranges from 0 to 17, allocates 4 points for having a neck circumference of more than 40 cm, 3 points for having a body-mass index of 25 kg/m(2) to less than 30 kg/m(2) or 5 points for having a body-mass index of 30 kg/m(2) or more, 2 points for snoring, 4 points for being older than 55 years of age, and 2 points for being male. Using a threshold of 8 points or more, the NoSAS score identified individuals at risk of clinically significant sleep-disordered breathing, with an area under the curve (AUC) of 0·74 (95% CI 0·72-0·76). It showed an even higher performance in the EPISONO cohort, with an AUC of 0·81 (0·77-0·85). The NoSAS score performed significantly better than did the STOP-Bang (AUC 0·67 [95% CI 0·65-0·69]; p<0·0001) and Berlin (0·63 [0·61-0·66]; p<0·0001) scores. INTERPRETATION The NoSAS score is a simple, efficient, and easy to implement score enabling identification of individuals at risk of sleep-disordered breathing. Because of its high discrimination power, the NoSAS score can help clinicians to decide which patients to further investigate with a nocturnal recording. FUNDING Faculty of Biology and Medicine of the University of Lausanne, Lausanne University Hospital, Swiss National Science Foundation, Leenaards Foundation, GlaxoSmithKline, and Vaud Pulmonary League.

Seasonal Variation of Overall and Cardiovascular Mortality: A Study in 19 Countries from Different Geographic Locations

Background Cardiovascular diseases (CVD) mortality has been shown to follow a seasonal pattern. Several studies suggested several possible determinants of this pattern, including misclassification of causes of deaths. We aimed at assessing seasonality in overall, CVD, cancer and non-CVD/non-cancer mortality using data from 19 countries from different latitudes. Methods and Findings Monthly mortality data were compiled from 19 countries, amounting to over 54 million deaths. We calculated ratios of the observed to the expected numbers of deaths in the absence of a seasonal pattern. Seasonal variation (peak to nadir difference) for overall and cause-specific (CVD, cancer or non-CVD/non-cancer) mortality was analyzed using the cosinor function model. Mortality from overall, CVD and non-CVD/non-cancer showed a consistent seasonal pattern. In both hemispheres, the number of deaths was higher than expected in winter. In countries close to the Equator the seasonal pattern was considerably lower for mortality from any cause. For CVD mortality, the peak to nadir differences ranged from 0.185 to 0.466 in the Northern Hemisphere, from 0.087 to 0.108 near the Equator, and from 0.219 to 0.409 in the Southern Hemisphere. For cancer mortality, the seasonal variation was nonexistent in most countries. Conclusions In countries with seasonal variation, mortality from overall, CVD and non-CVD/non-cancer show a seasonal pattern with mortality being higher in winter than in summer. Conversely, cancer mortality shows no substantial seasonality.

Prevalence and Determinants of Periodic Limb Movements in the General Population

Periodic limb movements during sleep (PLMS) are sleep phenomena characterized by periodic episodes of repetitive stereotyped limb movements. The aim of this study was to describe the prevalence and determinants of PLMS in a middle to older aged general population.

Prevalence of sleep apnoea syndrome in the middle to old age general population

On the basis of a large populationbased sample who underwent full polysomnography at home (HypnoLaus cohort), we recently reported that 49·7% of men and 23·4% of women aged 40 years or older had an apnoea-hypopnoea index of 15 events per h or more1 according to the American Academy of Sleep Medicine (AASM) 2013 scoring criteria. When excessive daytime sleepiness (ie, Epworth score >10 [maximum score 24]) was included in the definition with an apnoea-hypopnoea index of 5 events per h or more, the prevalence was 12·5% in men and 5·9% in women. This high prevalence of sleep disordered breathing reinforced the idea that the treatment decision should not only be based the apnoeahypopnoea index, but should also take into account associated symptoms and cardiovascular and metabolic comorbidities. After this Article was published, several readers contacted us to ask for the prevalence of sleep apnoea syndrome in our sample according to the International Classification of Sleep Disorders (ICSD-3) criteria. These criteria include either the presence of an apnoea-hypopnoea index of 5 events per h or more associated with obstructive sleep apnoearelated symptoms or cardiovascular and metabolic comorbidities, or an apnoea-hypopnoea index of 15 events per h or more (figure).

Sleep characteristics and cognitive impairment in the general population: The HypnoLaus study.

Objective: To assess the association between sleep structure and cognitive impairment in the general population. Methods: Data stemmed from 580 participants aged >65 years of the population-based CoLaus/PsyCoLaus study (Lausanne, Switzerland) who underwent complete sleep evaluation (HypnoLaus). Evaluations included demographic characteristics, personal and treatment history, sleep complaints and habits (using validated questionnaires), and a complete polysomnography at home. Cognitive function was evaluated using a comprehensive neuropsychological test battery and a questionnaire on the participants everyday activities. Participants with cognitive impairment (global Clinical Dementia Rating [CDR] scale score > 0) were compared with participants with no cognitive impairment (global CDR score = 0). Results: The 291 participants with a CDR score > 0 (72.5 ± 4.6 years), compared to the 289 controls with CDR = 0 (72.1 ± 4.6 years), had significantly more light (stage N1) and less deep (stage N3) and REM sleep, as well as lower sleep efficiency, higher intrasleep wake, and higher sleepiness scores (all p < 0.05). Sleep-disordered breathing was more severe in participants with cognitive impairment with an apnea/hypopnea index (AHI) of 18.0 (7.8–35.5)/h (p50 [p25–p75]) (vs 12.9 [7.2–24.5]/h, p < 0.001), and higher oxygen desaturation index (ODI). In the multivariate analysis after adjustments for confounding variables, the AHI and the ODI ≥4% and ≥6% were independently associated with cognitive impairment. Conclusions: Participants aged >65 years with cognitive impairment have higher sleepiness scores and a more disrupted sleep. This seems to be related to the occurrence of sleep-disordered breathing and the associated intermittent hypoxia.

Performance of blood pressure-to-height ratio at a single screening visit for the identification of hypertension in children.

Background: The diagnosis of hypertension in children is difficult because of the multiple sex-, age-, and height-specific thresholds to define elevated blood pressure (BP). Blood pressure-to-height ratio (BPHR) has been proposed to facilitate the identification of elevated BP in children. Objective: We assessed the performance of BPHR at a single screening visit to identify children with hypertension that is sustained elevated BP. Method: In a school-based study conducted in Switzerland, BP was measured at up to three visits in 5207 children. Children had hypertension if BP was elevated at the three visits. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) for the identification of hypertension were assessed for different thresholds of BPHR. The ability of BPHR at a single screening visit to discriminate children with and without hypertension was evaluated with receiver operating characteristic (ROC) curve analyses. Results: The prevalence of systolic/diastolic hypertension was 2.2%. Systolic BPHR had a better performance to identify hypertension compared with diastolic BPHR (area under the ROC curve: 0.95 vs. 0.84). The highest performance was obtained with a systolic BPHR threshold set at 0.80 mmHg/cm (sensitivity: 98%; specificity: 85%; PPV: 12%; and NPV: 100%) and a diastolic BPHR threshold set at 0.45 mmHg/cm (sensitivity: 79%; specificity: 70%; PPV: 5%; and NPV: 99%). The PPV was higher among tall or overweight children. Conclusion: BPHR at a single screening visit had a high performance to identify hypertension in children, although the low prevalence of hypertension led to a low PPV.

Clinical and course characteristics of depression and all-cause mortality: A prospective population-based study

BACKGROUND Given the large heterogeneity of depressive disorders (DD), studying depression characteristics according to clinical manifestations and course is a more promising approach than studying depression as a whole. The purpose of this study was to determine the association between clinical and course characteristics of DD and incident all-cause mortality. METHODS CoLaus|PsyCoLaus is a prospective cohort study (mean follow-up duration=5.2 years) including 35-66 year-old randomly selected residents of an urban area in Switzerland. A total of 3668 subjects (mean age 50.9 years, 53.0% women) underwent physical and psychiatric baseline evaluations and had a known vital status at follow-up (98.8% of the baseline sample). Clinical (diagnostic severity, atypical features) and course characteristics (recency, recurrence, duration, onset) of DD according to the DSM-5 were elicited using a semi-structured interview. RESULTS Compared to participants who had never experienced DD, participants with current but not remitted DD were more than three times as likely to die (Hazard Ratio: 3.2, 95% CI: 1.1-10.0) after adjustment for socio-demographic and lifestyle characteristics, comorbid anxiety disorders, antidepressant use, and cardiovascular risk factors and diseases. There was no evidence for associations between other depression characteristics and all-cause mortality. LIMITATIONS The small proportion of deceased subjects impeded statistical analyses of cause-specific mortality. CONCLUSIONS A current but not remitted DD is a strong predictor of all-cause mortality, independently of cardiovascular or lifestyle factors, which suggests that the effect of depression on mortality diminishes after remission and further emphasizes the need to adequately treat current depressive episodes.

The NoSAS score: A new and simple screening tool for obstructive sleep apnea syndrome in depressive disorder.

BACKGROUND Since the clinical presentation of obstructive sleep apnea syndrome (OSAS) shares common features with major depressive (MDE), the screening of OSAS is challenging in this population. The aim of this study was to assess the effectiveness of the NoSAS score in predicting the presence of OSAS among participants with current MDE and to compare it with the performance of existing screening tools. METHODS A random sample of the population-based cohort CoLaus (Lausanne, Switzerland) underwent a psychiatric evaluation (PsyCoLaus) and a complete polysomnography at home (HypnoLaus). The effectiveness of the NoSAS score in detecting the risk of significant OSAS among current MDE participants was assessed and compared with STOP-BANG and Berlin scores. RESULTS Among the 1761 subjects (58,75 ± 11y.o.; 47,8%men) who underwent polysomnography, significant OSAS was present in 24.0% with and 26.1% without current MDE. Using a threshold of ≥ 8 points, the NoSAS score identified OSAS in MDE participants with a sensitivity of 0.79, a specificity of 0.66, a negative predictive value of 0.91, and a positive predictive value of 0.41. The area under the ROC curve was 0.72 for NoSAS, 0.66 for STOP-BANG and 0.69 for the Berlin score (NS). LIMITATIONS Only 44% of the PsyCoLaus participants had a polysomnography. The studied population was mainly of Caucasian ancestry and above 40 years of age. CONCLUSIONS This is the first study assessing the performance of screening tools for OSAS in MDE. The NoSAS score is a simple and efficient screening tool for OSAS in this population, and may be a helpful instrument for clinicians.