Circadian misalignment is associated with a high cardiovascular risk among shift workers: is this an opportunity for prevention in occupational settings?

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Fundação para a Ciência e Tecnologia (FCT) and Fundo Social Europeu (FSE)

Introduction

Atypical work schedules encompass more than 20% of the European workforce. The link between shift work and cardiovascular disease (CVD) has been extensively studied being lifestyle behaviours, sleep disruption and circadian misalignment the key mechanisms involved. Social Jetlag (SJL) has been proposed as a proxy for circadian misalignment in epidemiological studies, once it takes into account  individual’s chronotype and working schedules. Therefore we hypothesize that, among  workers under fixed atypical work schedules, those with a greater SJL have a higher CVD risk.

Methods

A cross-sectional observational study was conducted among blue-collar workers of one retail company. Fixed working schedules were early morning, late evening, and night work. Sociodemographic, occupational, lifestyle and sleep data were collected through questionnaire. SJL was quantified by the difference for mid-sleep points on work- and free-days. Even though SJL is a continuous variable, 3 categories have been used (≤2h; 2-4h; ≥4h). Blood pressure (BP) and the total cholesterol (TC) were assessed. The CVD risk was estimated according to the relative risk SCORE chart. A relative risk≥3 was considered "high CVD risk". Descriptive statistics and bivariate analysis according to the CVD risk (high vs other) was performed. The relationship between SJL and high CVD risk was analysed through logistic binary regression using generalized linear models adjusted for age, sex, education, Body Mass Index, consumptions, sleep duration and quality plus work schedule and seniority.

Results

Of the 301 workers, 56.1% were male with a mean age of 33.0 ± 9.4years. Average SJL was 1:57 ± 1:38hours with the majority of workers experiencing ≤2h (59.4%) and 8% (n = 24) more than 4h. Less than a half had hypercholesterolemia (48.8%), overweight (37.9%)or hypertensive values (10.6%), however 50.5% were currently smokers. We found a significant trend for hypertension (p = 0.006) and smoking prevalence (p = 0.043) among ordinal SJL categories. A relative "high CVD risk" was found in 20.3% of the sample (n = 61). These workers were significantly older (p < 0.001), less educated (p = 0.003) and slept less hours on workdays (p = 0.021). In the multiple regression analysis, SJL was an independent risk factor for a "high CVD risk" (p = 0.029).The odds of having a "high CVD risk" increased almost thirty per cent  per each additional hour of SJL (OR = 1.29; 95% CI:1.03-1.63), even after adjusting for sociodemographic, lifestyle, sleep and working features.

Conclusions

We found compelling evidence that a greater SJL was associated with a bigger chance of high CVD risk. From this innovative perspective, the focus is not just on the working schedule itself but also on the worker’s chronotype. These findings suggest that interventions aimed to reduce Social Jetlag, especially in extreme chronotypes and working schedules, poses a great opportunity to minimize the cardiovascular health impact of shift work.

Does shift work affect blood pressure values and hypertension risk? a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Fundação para a Ciência e Tecnologia (FCT) and Fundo Social Europeu (FSE)

Introduction

Modern societies function 24h/day which accounts for shift work (SW) encompassing already more than 20% of the European workforce. While the relationship between blood pressure (BP) and cardiovascular events is a continuous, hypertension (HTN) remains the major preventable cause of cardiovascular disease (CVD) in our continent. SW has been associated with sleep disturbances, circadian misalignment and unhealthy behaviours, possibly conducting to several chronic diseases. Therefore, we aimed to determine if shift workers have higher BP values and/or HTN risk.

Methods

This systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A literature search was performed on MEDLINE, EMBASE and Cochrane electronic databases. Included studies reported HTN diagnosis using current thresholds and/or BP values, in both shift workers and in a control group of day workers. SW was categorized in 4 subgroups, focused mostly on night work. Pooled mean difference and 95% Confidence Intervals (95%IC) were estimated for continuous outcomes, Systolic BP (SBP) and diastolic BP (DBP), and pooled Odds Ratio and 95%IC were determined for HTN risk. The Newcastle-Ottawa Quality Assessment Scale was used for quality evaluation of included studies.

Results

Forty-five independent studies were included engaging 117252 workers. Of these, 41 studies were included in the meta-analysis for SBP, 39 for DBP and 14 for HTN. Most studies provided cross-sectional data (n = 42), were developed in Asia (n = 21), in an industrial setting (n = 25) and included only men (n = 26). Most studies were rated as satisfactory quality (n = 23) with confounder adjustment being the weakest parameter.

We found a statically significant increase for both systolic and diastolic BP among permanent night workers, 2.52mmHg [0.75–4.29] and 1.77mmHg [0.39–3.15] respectively. Amongst rotational shift workers, both with and without night work, we found a significant increase only for SBP, namely 1.28 mmHg [0.18–2.39] and 0.65 mmHg [0.07–1.22]. For HTN risk, none of SW types showed significant differences.

Conclusions

Certain groups of shift workers may be at special risk for increased BP. This is the first review assessing the impact of SW specifically on BP values. Although the increases were generally modest, these may play an important role among already susceptible individuals exposed overtime. The effect of SW was more consistent for SBP, which has a major impact on CVD risk. Hence, occupational health services should embrace a holistic CVD preventive approach including atypical risk factors such as SW, with active monitoring across the lifespan of more vulnerable workers.

Low energy availability and low body fat of female gymnasts before an international competition

The purpose of the present study was to evaluate dietary intake and body composition of elite rhythmic gymnastics (RG) athletes prior to a competition event. Sixty-seven rhythmic gymnasts (18.7 ± 2.9 years old) of high performance level, with 36.6 ± 7.6 h of training/week were evaluated in order to collect training and competition data, medical and gynaecological history, detailed dietary intake and body composition before an international competition. The majority of the participants (n = 40; 59.7%) had already menstruated, but age of menarche was delayed (15.3 ± 1.3 years) and all revealed menstrual irregularities. Gymnasts' body mass (48.4 ± 4.9 kg) and body mass index (BMI; 17.4 ± 1.1 kg/m(2)) were below the normal for age, and height (1.66 ± 0.05 m) was normal or even slightly above normal for age. Body fat was 9.0 ± 2.0% with no significant differences between age strata. Gymnasts exhibited low energy availability (EA; 31.5 ± 11.9 kcal/kg fat-free mass (FFM)/day). The average carbohydrate and protein intakes were 5.1 ± 2.3 g/kg/day and 1.6 ± 04 g/kg/day, which correspond to 51.4 ± 7.2% and 16.9 ± 3.4% of total energy intakes, respectively; average fat contribution was 33.0 ± 5.3%. Low intakes of pantothenic acid, folate and vitamins D, E and K and of minerals, including calcium, iron and magnesium were reported. Intakes of thiamine, riboflavin, niacin, vitamins A, B-6, B-12, C and manganese and zinc were above-adequate (P < 0.05). Low EA, low body fat and micronutrient deficiencies are common among RG.

Erectile dysfunction, obstructive sleep apnea syndrome and nasal CPAP treatment

BACKGROUND AND PURPOSE

To evaluate the effect of one month of continuous positive airway pressure (CPAP) in a subgroup of obstructive sleep apnea (OSA) patients with erectile dysfunction (ED) and compare this subgroup with age- and body mass index (BMI)-matched OSA patients without ED.

PATIENTS AND METHODS

Prospective general, sleep, psychiatric and sexologic evaluations were conducted. Epworth Sleepiness Scale (ESS), Beck Depression Inventory (BDI), Sleep Disorders Questionnaire (SDQ), Quality of Life SF-36, and polysomnography were used. Seventeen OSA patients with ED were compared prior to CPAP treatment and during CPAP treatment with age- and BMI-matched OSA patients without ED. Parametric and non-parametric statistics, chi-square, Fisher exact test and multiple regression analyses were performed.

RESULTS

Ninety-eight men (BMI=28.8 kg/m2, apnea-hypopnea index (AHI)=49.6 events/h, ESS=14.8, BDI=8.4, and lowest SaO2=75.3%) were divided into subgroups of lowest SaO2>80% (A) and lowest SaO2< or =80% (B). (A) Forty-six men had a mean lowest SaO2 of 85.7%+/-2.9, AHI=29.5+/-17.6, age=46.3+/-9.3 years, ESS=13.6+/-4.2, BMI=25.8+/-4.8. Seven of the patients had ED. (B) Fifty-two men had a mean lowest SaO2=60.10+/-10.0%, AHI=67.4+/-24.5, BDI=9.0+/-6.9, age=47.4+/-9.4 years, ESS=16.2+/-4.4, BMI=31.4+/-5.1. Twenty-one of the patients had ED (chi2: P=0.006). Significant variables for ED were lowest SaO2 and age (r=0.17). CPAP-treated subgroup: ED subjects had significantly lower SaO2, ESS, BDI and SF-36 subscale scores than OSA controls. Nasal CPAP eliminated the differences between groups, and ED was resolved in 13 out of 17 cases.

CONCLUSIONS

ED in OSAS is related to nocturnal hypoxemia, and about 75% of OSAS patients with ED treated with nasal CPAP showed remission at one-month follow-up, resulting in significant improvement in quality of life.

Prevalence of narcolepsy symptomatology and diagnosis in the European general population

OBJECTIVE

To determine the prevalence of narcolepsy in the general population of five European countries (target population 205,890,882 inhabitants).

METHODS

Overall, 18,980 randomly selected subjects were interviewed (participation rate 80.4%). These subjects were representative of the general population of the UK, Germany, Italy, Portugal, and Spain. They were interviewed by telephone using the Sleep-EVAL expert system, which provided narcolepsy diagnosis according to the International Classification of Sleep Disorders (ICSD).

RESULTS

Excessive daytime sleepiness was reported by 15% of the sample, with a higher prevalence in the UK and Germany. Napping two times or more in the same day was reported by 1.6% of the sample, with a significantly higher rate in Germany. Cataplexy (episodes of loss of muscle function related to a strong emotion), a cardinal symptom of narcolepsy, was found in 1.6% of the sample. An ICSD narcolepsy diagnosis was found in 0.047% of the sample: The narcolepsy was severe for 0.026% of the sample and moderate in 0.021%.

CONCLUSION

This is the first epidemiologic study that estimates the prevalence of narcolepsy in the general population of these five European countries. The disorder affects 47 individuals/100,000 inhabitants.

Neurological teleconsultation for general practitioners

A neurology teleconsulting network was implemented between a university hospital in Lisbon and five nearby health centres. PCs equipped for videoconferencing were installed, connected by ISDN lines at 128 kbit/s. Fifty-three general practitioners (GPs) were surveyed. The survey showed that the GPs had difficulties in using computers, but they had definite intentions to use teleconsultation for neurology cases and 83% of the respondents stated that they would probably use the technique. During the study, 90 neurology teleconsultations took place over 55 weeks. The average consultation rate was 1.6 teleconsultations per week (SD 1.3, range 0-6). The conferences lasted 10-45 min. Longer teleconsultations were mainly due to technical difficulties in using computers on the part of users with a low level of computer literacy. The patients were 42 males and 46 females, with a mean age of 38 years (SD 20, range 1-84); two patients were discussed twice. The benefits consisted mainly of advice on patient medication, diagnosis and the prevention of unnecessary specialist consultations or laboratory examinations. Doctor-doctor teleconsultation allows the rapid resolution of queries which otherwise cause stress to patients and increase the cost and complexity of care.

The sleep tutorial

A multimedia Sleep tutorial for General Practitioners was implemented from scratch. The implementation had into account the following features: 1) Specific needs of GPs evaluated in 3 different countries, related with Tutorial contents and technical features; 2) Multinational authorship from European experts; 3) Multilingual possibilities; 4) User friendliness and easy navigation. The tutorial was implemented and tested and its gama version is now available for commercialization.

PSG-EXPERT. An expert system for the diagnosis of sleep disorders

This paper describes PSG-EXPERT, an expert system in the domain of sleep disorders exploring polysomnographic data. The developed software tool is addressed from two points of view: (1)--as an integrated environment for the development of diagnosis-oriented expert systems; (2)--as an auxiliary diagnosis tool in the particular domain of sleep disorders. Developed over a Windows platform, this software tool extends one of the most popular shells--CLIPS (C Language Integrated Production System) with the following features: backward chaining engine; graph-based explanation facilities; knowledge editor including a fuzzy fact editor and a rules editor, with facts-rules integrity checking; belief revision mechanism; built-in case generator and validation module. It therefore provides graphical support for knowledge acquisition, edition, explanation and validation. From an application domain point of view, PSG-Expert is an auxiliary diagnosis system for sleep disorders based on polysomnographic data, that aims at assisting the medical expert in his diagnosis task by providing automatic analysis of polysomnographic data, summarising the results of this analysis in terms of a report of major findings and possible diagnosis consistent with the polysomnographic data. Sleep disorders classification follows the International Classification of Sleep Disorders. Major features of the system include: browsing on patients data records; structured navigation on Sleep Disorders descriptions according to ASDA definitions; internet links to related pages; diagnosis consistent with polysomnographic data; graphical user-interface including graph-based explanatory facilities; uncertainty modelling and belief revision; production of reports; connection to remote databases.

Headache tutorial

The headache multimedia educational tool for the general practitioners, consists of five different modules, i.e. classification, clinical data, headache tutorial, diagnostic headache diary and nomenclature. It is possible to move between the modules both vertically and horizontally. This paper concerns the headache tutorial. It consist of case records that the user can test his diagnostic abilities on. Each case record is subdivided into an interview by the physician, physical and neurological examination, laboratory test, sum of positive diagnostic elements, suggestions of diagnoses and management. A total of 12 case records are provided. The system will be available on a CD-ROM.

General practitioners and neurotelemedicine

Predicting attitudes towards teleconsultation systems and intentions of use is crucial at the beginning of the implementation phase, due to the critical role of human factors in its acceptance and continuous utilisation. The main objective of this study was to assess and understand GP's attitudes and intentions towards using the teleconsultation system in Neurology, implemented in Lisbon, between Hospital de Santa Maria/Neurology Outpatient Clinic and the Health Care Centers of its Health Unit. The final aim is the promotion of a wide acceptance and utilisation of the system, through the development of adequate communication strategies. A predictive model "Theory of Reasoned Action" was chosen as method. It was operated with the application of a questionnaire to a sample of 53 GP's, developed from the results of a content analysis of 10 interviews. A total of 44 GP's stated that, probably they will use the system, 5 were neutral and 4 probably will not use it. The responses were submitted to factor and multiple regression analysis. Attitude was determined by only one factor "Accessibility and Quality" (b = 0.486; p = 0.007) from the 5 factors obtained. The intention variance was explained in 26.9% by the attitude and subjective norm. However, only the attitudinal factor (b = 0.469; p = 0.002) contributes significantly to its explanation with no significant influence from the subjective norm. GP's intentions towards using the system are very positive. Nevertheless, there are significant differences between the centers that are participating and not participating in the project. Communication strategies envisaging dissemination and generalised acceptance and utilisation should focus on accessibility and quality of care aspects.

Nocturnal sleep quality and circadian blood pressure variation

OBJECTIVE

To verify whether non-dipper behavior is associated with poor nocturnal sleep quality and a higher rate of obstructive sleep apnea than dipper behavior.

METHODS

A sample of 36 subjects older than 50 years (mean age = 70 +/- 6.49 years), 8 males and 28 females, 27 (75%) hypertensive and 9 (25%) normotensive, was studied. Nocturnal polysomnography was carried out in the patients' homes. 24-hour ambulatory blood pressure was studied with Spacelabs 90,207 device. The statistical tests used were Student's t test, Pearson's correlation and the Chi-square test.

RESULTS

In the overall sample, higher rates of apnea, higher rates of arousal and shorter duration of the REM (rapid eye movement) phase were linked to high levels of nocturnal diastolic blood pressure, with statistical significance (p < 0.01, p < 0.01, p < 0.05 respectively). Sleep fragmentation was associated with the lowest percentages of variation in daytime to nighttime systolic blood pressure (p < 0.03). Apnea rates were significantly higher in the hypertensive group compared to the normal blood pressure population (p = 0.04). We also observed that higher rates of nocturnal apnea corresponded to lower variations in daytime to nighttime systolic blood pressure (p = 0.015) and to a lower dipper index (p < 0.05). Higher indexes of arousal and lower REM latency were associated with higher nocturnal blood pressure, both systolic (p = 0.039 and p = 0.008, respectively) and diastolic (p = 0.003 and p = 0.029, respectively). Sleep efficiency was also negatively correlated with mean levels of nocturnal diastolic blood pressure (p = 0.038).

CONCLUSIONS

The quality of nocturnal sleep seems to play an important role in blood pressure levels, particularly in the nocturnal blood pressure profile. A poor quality of nocturnal sleep and the rate of obstructive sleep apnea were associated with non-dipper behavior in the hypertensive population. Sleep evaluation is particularly useful in non-dipper subjects with hypertension.