Sleep quality in addition to duration needs to be considered in CVD prevention
Short sleepers, especially those with poor sleep quality, have an increased risk of total cardiovascular disease (CVD) and Coronary Heart Disease (CHD) concludes a 15 year Dutch follow-up study (abstract number 10298). The abstract, which has been nominated for a young investigator award at EuroPRevent, is the first study to take rising feeling rested into account when assessing sleep in relation to CVD.
Several investigations have found an increased risk of CVD in short sleepers compared to normal sleepers. “However, what these studies didn’t take into account is that for some people short sleep duration may be sufficient to recover, whereas in others it isn’t. Sleep quality may modify the association between sleep duration and CVD,” said Marieke Hoevenaar-Blom, the first author of the study.
In the MORGEN (Monitoring Project on Risks Factors and Chronic Diseases in the Netherlands) study, Hoevenaar-Blom and colleagues from the National Institute for Public Health and the Environment (Bilthoven, The Netherlands), explored the combined associations of sleep duration and quality with CVD and CHD incidence. “We hypothesized that the risk of CVD was largest in short sleepers who don’t rise feeling rested in the morning,” said Hoevenaar-Blom.
In the study, information on sleep duration and sleep quality was obtained by a self- administered questionnaire filled in by 20,432 participants (9,217 men and 11,215 women) between 1993 and 1997. Over 10 to 15 years of follow-up morbidity data, vital status and causes of death were then obtained through linkage with several national registries. The average sleep duration was assessed by asking participants “How many hours of sleep do you usually get per 24 hour period?” Short sleep duration was defined as sleeping six hours or less; while long sleep duration was sleeping nine hours or more per 24 hour period. Information on sleep quality was assessed in the first two years of baseline measurements with the question “Do you usually rise rested?”
After 10 to 15 years of follow-up (mean 11.9 years), 1,486 participants developed CVD of whom 177 had a fatal event. After adjusting for relevant confounders, short sleepers had a 15% higher risk of incident CVD compared to participants with normal sleep duration. On its own no association was found between sleep quality and CVD incidence, but when assessing sleep quality in combination with sleep duration, short sleepers with bad sleep quality had a 65% higher risk of CVD and a 85% higher risk of CHD compared to participants with a normal sleep duration and good sleep quality. The investigators found no association between a long sleep duration and CVD.
“Our results show that in preventing cardiovascular events, sleep duration and quality both need to be taken in to account,” said Hoevenaar-Blom.
During sleep the body physiologically recovers. “Therefore, those not sleeping according to their needs (short sleep duration and poor quality) don’t entirely recover,” said Hoevenaar-Blom, adding that in future studies more research needs to be undertaken to elucidate the exact mechanism for the relationship between sleep deprivation and CVD.
Blood donation provides opportunity for cardiovascular screening
Blood donation could provide a unique opportunity for population wide surveillance screening for the early detection of CVD risk, suggests a US abstract (number 10154).
Cholesterol screening is widely accepted as one measure of future CVD risk. In the study Stephen Eason and colleagues, from Carter Blood Care (Bedford, Texas, US), decided to investigate whether measuring total non fasting cholesterol on volunteer blood donors at each donation might help identify individuals at risk of future CVD. The study targeted young individuals since they were considered less likely to be aware of their risk status and less likely to be taking pharmacological agents for cholesterol control.
In the study, investigators reviewed non fasting total cholesterol levels of 5,615 Caucasian volunteers, aged between 20 and 39 years of age at their first donation in 2002, and at a second donation in 2008.
The results showed that the average cholesterol was 4.4 mmol/L for females and 4.6 mmol/L for males in 2002; but that by 2008 readings had risen to 4.8 mmol/L for females and 4.9 mmol/L for males.
“The study showed that population-wide screening of individuals in the blood donor setting can identify a significant number of people who are at a greater risk of future CVD and who could benefit from further evaluation,” said Eason, adding that they also showed how CVD risk increases with time.
Cholesterol, he added, is just one metabolic maker used to determine CVD risk. “Additional studies with metabolic markers such as HDL-C for cardiovascular disease and A1c for diabetes need to be explored to determine which might be appropriate for population wide screening,” he said.
Weight loss benefits for blood pressure quantified
Losing weight has a beneficial effect on blood pressure, concludes the SHIP cohort study. The German research, presented as an abstract (number 10433)at the EuroPRevent meeting, for the first time in a population-based study, quantified the fall in blood pressure that can be achieved with a given weight loss.
“Our findings serve to emphasize the importance of controlling the development of obesity in the primary prevention of hypertension at the overall level of the population,” said the first author Marcello Markus, adding that there is an urgent need to increase awareness among both health professionals and the general public about the health hazards of obesity.
In the population-based Study of Health in Pomerania (SHIP), Markus and colleagues, from Ernst Moritz Arndt University of Greifswald, (Germany), examined 3,300 subjects from West Pomerania, in the northeast area of Germany, on two separate occasions spaced five years apart. Both times the investigators recorded information on blood pressure and weight.
Results showed that a relative change of 1% in weight was associated with a relative change of 0.24% in systolic blood pressure, 0.26% in diastolic blood pressure, 0.25% in mean arterial pressure and 0.20% in pulse pressure. Furthermore the study showed that an absolute change of 1 kg in weight was associated with an absolute change of 0.39 mmHg in systolic, 0.26 mmHg in diastolic, 0.30 mmHg in mean arterial blood pressure and 0.13 mmHg in pulse pressure.
After five years of follow-up, the authors conclude, individuals who lost at least 5% of their initial weight had the greatest chance to control blood pressure levels without medication and to have fewer cardiovascular events. “The data suggest that for individuals who already have established hypertension, the loss in total body weight increases the probability for a normalisation of blood pressure levels,” said Markus
Ongoing studies of subgroups with different initial weight values, add the authors, are necessary to explore whether weight loss has a universal benefit on blood pressure. “During the natural ageing process, the majority of individuals increase their waist circumference, even when they lose some weight, and this association between weight, waist circumferences and blood pressure is not quite clear,” explained Markus.
Antithrombotic therapies could protect elderly from cold weather CVD deaths
An increased thrombotic tendency during the winter months could explain the increased CV morbidity and mortality observed during the same time period, finds a UK abstract (number P521). The thrombotic tendency, suggest the investigators, might potentially be preventable by prescribing antithrombotic therapies to elderly patients.
In Great Britain, according to the Office of National Statistics, there is known to be a 15 % excess of CV deaths during December to March compared with April to November among men aged 65 to 84 years. Other studies have suggested that this pattern of excess winter mortality is common in southern as well as northern European countries. In an attempt to explain the “winter effect” Richard Morris and colleagues, from University College (London, UK) investigated the haemostatic variables known to be associated with CHD incidence.
In the study 4088 men aged between 60 and 79 years, from 24 towns across Britain, were examined between January 1998 and March 2000 for the following biochemical measures: tissue plasminogen activator (t-PA), von Willebrand Factor (vWF) and fibrin D-Dimer. Although each participant provided only one measurement, all the months of the year were represented by an average of over 300 participants per month. The investigators produced a cosinor analysis, where curves shaped like waves depicted changes in each measure over the course of the year.
The results showed that all three markers peaked in the winter months, with vWF and D-Dimer peaking in December and t-PA in January. The difference in mean between winter and non-winter months was 0.92ng/mL for t-PA, 6.82 IU/dL for vWF and 0.103 ng/mL for D-Dimer, after adjustment for relevant confounding factors. These results, the investigators calculated, would lead to an overall 9.1% excess CHD mortality in winter.
“Older people whose risk of CHD is already high might potentially be protected by interventions to lower their risk during cold weather,” suggested Morris, adding that the study needs to be replicated and undertaken in women. “If the hypothesis still seems to stand, studies should evaluate suitable interventions to assess the benefits of reducing haemostasis in winter months among people considered at high risk.”