More Evidence of Causal Link between Air Pollution and Early Death

Strengthening U.S. air quality standards for fine particulate pollution to be in compliance with current World Health Association (WHO) guidelines could save more than 140,000 lives over the course of a decade, according to a new study from Harvard T.H. Chan School of Public Health.

The study, published June 26, 2020 in Sciences Advances, provides the most comprehensive evidence to date of the causal link between long-term exposure to fine particulate (PM2.5) air pollution and premature death, according to the authors.

“Our new study included the largest-ever dataset of older Americans and used multiple analytical methods, including statistical methods for causal inference, to show that current U.S. standards for PM2.5 concentrations are not protective enough and should be lowered to ensure that vulnerable populations, such as the elderly, are safe,” said doctoral student Xiao Wu, a co-author of the study.

The new research builds on a 2017 study that showed that long-term exposure to PM2.5 pollution and ozone, even at levels below current U.S. air quality standards, increases the risk of premature death among the elderly in the U.S.

For the new study, researchers looked at 16 years’ worth of data from 68.5 million Medicare enrollees—97% of Americans over the age of 65—adjusting for factors such as body mass index, smoking, ethnicity, income, and education. They matched participants’ zip codes with air pollution data gathered from locations across the U.S. In estimating daily levels of PM2.5 air pollution for each zip code, the researchers also took into account satellite data, land-use information, weather variables, and other factors. They used two traditional statistical approaches as well as three state-of-the-art approaches aimed at teasing out cause and effect.

Results were consistent across all five different types of analyses, offering what authors called “the most robust and reproducible evidence to date” on the causal link between exposure to PM2.5 and mortality among Medicare enrollees—even at levels below the current U.S. air quality standard of 12 μg/m3 (12 micrograms per cubic meter) per year.

The authors found that an annual decrease of 10 μg/m3 in PM2.5 pollution would lead to a 6%–7% decrease in mortality risk. Based on that finding, they estimated that if the U.S. lowered its annual PM2.5 standard to 10 μg/m3—the WHO annual guideline—143,257 lives would be saved in one decade.

The authors included additional analyses focused on causation, which address criticisms that traditional analytical methods are not sufficient to inform revisions of national air quality standards. The new analyses enabled the researchers, in effect, to mimic a randomized study—considered the gold standard in assessing causality—thereby strengthening the finding of a link between air pollution and early death.

“The Environmental Protection Agency has proposed retaining current national air quality standards. But, as our new analysis shows, the current standards aren’t protective enough, and strengthening them could save thousands of lives. With the public comment period for the EPA proposal ending on June 29, we hope our results can inform policymakers’ decisions about potentially updating the standards,” said co-author Francesca Dominici, Clarence James Gamble Professor of Biostatistics, Population, and Data Science.

Source: Harvard T.H. Chan School of Public Health

Study: Sedentary Behavior Independently Predicts Cancer Mortality

In the first study to look at objective measures of sedentary behavior and cancer mortality, researchers from The University of Texas MD Anderson Cancer Center found that greater inactivity was independently associated with a higher risk of dying from cancer. The most sedentary individuals had an 82% higher risk of cancer mortality compared to the least sedentary individuals. An accelerometer was used to measure physical activity, rather than relying on participants to self-report their activity levels.

“This is the first study that definitively shows a strong association between not moving and cancer death,” said Susan Gilchrist, M.D., associate professor of Clinical Cancer Prevention and lead author of the study, published today in JAMA Oncology. “Our findings show that the amount of time a person spends sitting prior to a cancer diagnosis is predictive of time to cancer death.”

Researchers also found that replacing 30 minutes of sedentary time with physical activity was associated with a 31% lower risk of cancer death for moderate-intensity activity, such as cycling, and an 8% lower risk of cancer death for light-intensity activity, such as walking.

“Conversations with my patients always begin with why they don’t have time to exercise,” said Gilchrist, who leads MD Anderson’s Healthy Heart Program. “I tell them to consider standing up for 5 minutes every hour at work or taking the stairs instead of the elevator. It might not sound like a lot, but this study tells us even light activity has cancer survival benefits.”

Study design

This study involved a cohort of participants from the nationally representative REGARDS study, which recruited more than 30,000 U.S. adults over the age of 45 between 2003 and 2007 to study long-term health outcomes.

To measure sedentary behavior, 8,002 REGARDS participants who did not have a cancer diagnosis at study enrollment wore an accelerometer on their hip during waking hours for seven consecutive days. The accelerometer data was gathered between 2009 and 2013. After a mean follow-up of 5 years, 268 participants died of cancer. Longer duration of sedentary behavior was independently associated with a greater risk of cancer death.

The study also found that engaging in either light or moderate to vigorous physical activity made a difference. Investigators assessed sedentary time, light-intensity physical activity (LIPA) and moderate to vigorous physical activity (MVPA) in the same model and found that LIPA and MVPA, not sedentary behavior, remained significantly associated with cancer mortality.

“From a practical perspective, this means that individuals who replaced either 10 to 30 minutes of sedentary time with either LIPA or MVPA had a lower risk of cancer mortality in the REGARDS cohort,” Gilchrist said.

The study had several limitations, including a potentially healthier participant sample compared to the full REGARDS cohort and a lack of site-specific cancer data, including type of tumor and treatment.

“Our findings reinforce that it’s important to ‘sit less and move more’ and that incorporating 30 minutes of movement into your daily life can help reduce your risk of death from cancer,” Gilchrist said. “Our next step is to investigate how objectively measured sedentary behavior impacts site-specific cancer incidence and if gender and race play a role.”

Source: The University of Texas MD Anderson Cancer Center


Today’s Comic

Physical Activity Prevents almost four million Early Deaths Worldwide Each Year

At least 3.9 million early deaths are being averted worldwide every year by people being physically active, according to a new study published in The Lancet Global Health today by researchers at the Universities of Cambridge and Edinburgh.

The team behind the study argue that too often we focus on the negative health consequences of poor levels of physical activity when we could be celebrating the achievements of physical activity.

Professor Paul Kelly from the Physical Activity for Health Research Centre at the University of Edinburgh said:

Research into lifestyle factors such as lack of physical activity, poor diet, drinking alcohol, and smoking, tends to focus on the harms these do to health, this helps create a narrative to try and prevent and reduce these behaviours. We also believe there is value in trying to understand the benefits that ‘healthy behaviours’ confer in order to argue for maintaining and increasing them. Can we look instead at population activity levels and estimate the health benefits of all this activity to society?”

In their study, Dr Tessa Strain from the MRC Epidemiology Unit at the University of Cambridge and colleagues used a number known as the Prevented Fraction for the Population – in this case, the proportion of deaths that were prevented because people are physically active.

The team looked at previously published data for 168 countries, on the proportion of the population meeting World Health Organization global recommendation of at least 150 minutes of moderate-intensity aerobic activity throughout the week, or 75 minutes of vigorous-intensity activity, or an equivalent combination. The proportion of the population meeting the recommended amount of physical activity varied substantially between countries, from 33% for Kuwait, to 64% for the United Kingdom, to 94% for Mozambique.

By combining these data with estimates of the relative risk of dying early for active people compared to inactive people, the authors were able to estimate the proportion of premature deaths that were prevented because people are physically active.

They found that globally, due to physical activity the number of premature deaths was an average (median) of 15% lower than it would have been – 14% for women and 16% for men – equating to approximately 3.9 million lives saved per year.

Despite considerable variation in physical activity levels between countries, the positive contribution of physical activity was remarkably consistent across the globe, with a broad trend towards a greater proportion of premature deaths averted for low- and middle-income countries. In low income countries, an average of 18% of premature deaths were averted compared to 14% for high income countries.

In the USA, 140,200 early deaths were prevented annually and in the UK 26,600.

Health experts often frame the debate in terms of the number of early deaths due to lack of physical activity, estimating that 3.2 million die prematurely each year. But the researchers say that by showing how many deaths are averted, it might also be possible to frame the debate in a positive way and this could have benefits to advocacy, policy and population messaging.

Dr Strain said:

“We’re used to looking at the downsides of not getting enough activity – whether that’s sports or a gym or just a brisk walk at lunchtime – but by focusing on the number of lives saved, we can tell a good news story of what is already being achieved. It tells us how much good is being done and helps us say ‘look how much benefit physical activity is already providing – let’s make things even better by increasing physical activity levels further. Although there’s a risk of complacency – people asking why we need to invest more when it’s already providing benefit – we hope our findings will encourage governments and local authorities to protect and maintain services in challenging economic climates.”

Six ways to keep active during lockdown

  • Go out for a daily walk, wheel, or whatever movement you are able to do
  • Go for a cycle ride or run if you’re able to
  • Do stretching exercises or yoga for your muscles and joints
  • If you have a garden, do some gardening – great for stretching and bending
  • Activity in greenspace or parks and activity with others may have additional mental and social health benefits
  • Join an online exercise session

Source: University of Cambridge

Blood Pressure Medications Help Even the Frailest Elderly People Live Longer

Taking blood pressure medication as prescribed helped even the frailest elderly people (65 and older) live longer, and the healthiest older people had the biggest survival boost, according to a large study in northern Italy published today in Hypertension, an American Heart Association journal.

“We knew that high blood pressure medication was protective in general among older people, however, we focused on whether it is also protective in frail patients with many other medical conditions who are usually excluded from randomized trials,” said Giuseppe Mancia, M.D., lead study author and professor emeritus at the University of Milano-Bicocca in Milan, Italy.

Researchers reviewed data on almost 1.3 million people aged 65 and older (average age 76) in the Lombardy region of northern Italy who had 3 or more high blood pressure medication prescriptions in 2011-2012. Examining the public health care database, researchers calculated the percentage of time over the next seven years (or until death) that each person continued to receive the medications. Because almost all medications are free or low-cost and dispensed by the public health service, this corresponds roughly to people’s adherence in using the medication in Italy.

To look separately at outcomes among older people with various medical conditions, researchers used a previously developed score that accounts for 34 different health factors and has a close relationship with mortality.

Researchers compared roughly 255,000 people who died during the 7-year follow-up with age-, gender-, and health-status-matched controls who survived and divided them into four groups of health status: good, medium, poor or very poor.

The probability of death over 7-years was 16% for people rated in good health at the beginning of the study. Mortality probability increased progressively to 64% for those rated in very poor health.

Compared with people with very low adherence to blood pressure medications (dispensed pills covered less than 25% of the time period), people with high adherence to blood pressure medications (more than 75% of the time period covered) were:

  • 44% less likely to die if they started in good health; and
  • 33% less likely to die if they started in very poor health.

A similar pattern was seen with cardiovascular deaths. The greatest survival benefit was among the people who started in good health, and the most modest survival benefit was in those who started in very poor health.

“Our findings definitely suggest that even in very frail people, antihypertensive treatment reduces the risk of death; however, the benefits may be smaller in this group,” Mancia said.

No matter what a person’s initial health status, survival benefits were greatest in those who received blood pressure medication to cover more than 75% of the follow-up period, compared with those with intermediate (25-75%) or low levels (less than 25%) of coverage, highlighting the importance of consistent use of blood pressure medications.

“Do your best to encourage and support patients to take their medications, because adherence is crucial to getting the benefits. Medications do nothing if people don’t take them,” Mancia said.

Prescription medications given to elderly people living in nursing homes or assisted-living homes in Italy are not included in the national database, so the study’s results may only apply to elderly people living in the community. In addition, all data for this analysis are from Italy, where hospitalizations and blood pressure medications are available for free or at low cost, thus, the study’s findings may not be generalizable to countries with a different health care system.

Source: American Heart Association


Today’s Comic

Walking or Cycling to Work Associated with Reduced Risk of Early Death

Kate Wighton wrote . . . . . . . . .

People who walk, cycle and travel by train to work are at reduced risk of early death or illness compared with those who commute by car.

These are the findings of a study of over 300,000 commuters in England and Wales, by researchers from Imperial College London and the University of Cambridge.

The researchers say the findings suggest increased walking and cycling post-lockdown may reduce deaths from heart disease and cancer.

The study, published in The Lancet Planetary Health, used Census data to track the same people for up to 25 years, between 1991-2016.

It found that, compared with those who drove, those who cycled to work had a 20 per cent reduced rate of early death, 24 per cent reduced rate of death from cardiovascular disease (which includes heart attack and stroke) during the study period, a 16 per cent reduced rate of death from cancer, and an 11 per cent reduced rate of a cancer diagnosis.

Walking to work was associated with a 7 per cent reduced rate in cancer diagnosis, compared to driving. The team explain that associations between walking and other outcomes, such as rates of death from cancer and heart disease, were less certain. One potential reason for this is people who walk to work are, on average, in less affluent occupations than people who drive to work, and more likely to have underlying health conditions which could not be fully accounted for.

Men more likely to cycle

The paper also revealed that compared with those who drove to work, rail commuters had a 10 per cent reduced rate of early death, a 20 per cent reduced rate of death from cardiovascular disease, and a 12 per cent reduced rate of cancer diagnosis. This is likely due to them walking or cycling to transit points, although rail commuters also tend to be more affluent and less likely to have other underlying conditions, say the team.

Dr Richard Patterson from the MRC Epidemiology Unit at the University of Cambridge who led the research said: “As large numbers of people begin to return to work as the COVID-19 lockdown eases, it is a good time for everyone to rethink their transport choices. With severe and prolonged limits in public transport capacity likely, switching to private car use would be disastrous for our health and the environment. Encouraging more people to walk and cycle will help limit the longer-term consequences of the pandemic.”

The study also assessed whether the benefits of each mode of travel differed between occupational groups and found that potential health benefits were similar across these groups.

The team used data from the UK Office for National Statistics Longitudinal Study of England and Wales, a dataset that links data from several sources including the Census of England and Wales, and registrations of death and cancer diagnoses.

The data revealed overall 66 per cent of people drove to work, 19 per cent used public transport, 12 per cent walked, and 3 per cent cycled. Men were more likely than women to drive or cycle to work, but were less likely to use public transport or walk.

Dr Anthony Laverty, senior author from the School of Public Health at Imperial College London explained: “It’s great to see that the government is providing additional investment to encourage more walking and cycling during the post-lockdown period. While not everyone is able to walk or cycle to work, the government can support people to ensure that beneficial shifts in travel behaviour are sustained in the longer term. Additional benefits include better air quality which has improved during lockdown and reduced carbon emissions which is crucial to address the climate emergency.”

The team add that the benefits of cycling and walking are well-documented, but use of Census data in this new study allowed large numbers of people to be followed up for a longer time. They explain that these analyses were unable to account for differences in participants’ dietary intakes, smoking, other physical activity or underlying health conditions. However, they add these findings are compatible with evidence from other studies.

Source: Imperial College London