Heart and lungs

Loneliness may increase death risk in people with heart conditions

"Lonely heart patients at 'increased risk of dying' after leaving hospital," reports The Independent.

A survey of people with heart diseases discharged from hospitals in Denmark found that those who said they felt lonely were more likely to report feeling depressed and anxious, report a lower quality of life and were almost 3 times more likely to have died within a year of being discharged.

Loneliness is not the same as living alone, however. People in the study who said they lived alone were less likely to experience anxiety, and no more likely to have died than people who lived with others.

The survey adds to evidence from previous studies drawing a link between loneliness, social isolation and poor outcomes for people with heart disease. The researchers say doctors should consider loneliness as part of their clinical risk assessment when treating heart patients.

However, because of the study design, we cannot say for sure that loneliness causes death from heart problems. Associated factors, such as lifestyle, may play a part.

We also do not know which came first for the people in the study – feeling lonely, or having heart problems.

If you (or someone you know) is concerned about loneliness, there is help available to connect you to others. Find out more about combatting social isolation in older people.

Where did the story come from?

The researchers who carried out the study came from 6 hospitals in Denmark:

  • Copenhagen University Hospital
  • National Institute of Public Health, University of Southern Denmark
  • Odense University Hospital
  • Aalborg University Hospital
  • Aarhus University Hospital
  • Herlev and Gentofte University Hospital

The study was funded by Helsefonden, the Danish heart centres, the Novo Nordisk Foundation, Familien Hede Nielsens Fond and the Danish Heart Association.

It was published in the peer-reviewed medical journal Heart, and is free to read online.

Mail Online and Independent both carried reasonably accurate and balanced stories about the study. However, they did not include absolute numbers for the people who had died, so it's hard to tell from these stories how significant the increased risk really was.

What kind of research was this?

This was a cross-sectional survey, combined with national registry data.

This type of study is useful for showing us what is happening in a group of people at 1 point in time. However, it cannot tell us whether any of the risk factors identified in the survey – such as loneliness – actually cause outcomes such as death.

What did the research involve?

Researchers gave questionnaires to all adult patients discharged from heart centres in Denmark over a 1-year period (15 April 2013 to 15 April 2014).

On the standardised questionnaire, people were asked about their health-related quality of life, symptoms of depression and anxiety, health behaviour (including smoking, drinking alcohol, compliance with taking prescribed medicine) and their weight and height.

They were also asked: "Does it ever happen that you are alone, even though you would prefer to be with other people?" Researchers defined loneliness as answering either "yes, often" or "yes, sometimes".

National databases were used to find out whether people lived alone or with others, and to track what happened to them. The researchers included people with:

  • coronary heart disease (narrowing of the blood vessels to the heart)
  • arrhythmia (irregular or fast heart rhythm)
  • heart failure (when the heart muscle can no longer pump blood effectively)
  • valve disease (when valves in the blood vessels around the heart do not work properly)

During the year after patients were discharged, the researchers recorded:

  • cardiac events (heart attack, stroke, cardiac arrest, ventricular tachycardia or fibrillation)
  • deaths from any cause

They then looked to see if people who lived alone or felt lonely had worse outcomes.

They adjusted the results to account for age, education level, diagnosis, other illnesses, body mass index (BMI), smoking, alcohol intake and taking medicines as prescribed. They also adjusted figures assessing loneliness for the effects of living alone, and vice versa.

What were the basic results?

Just over half of people surveyed returned the questionnaire. Some people (17) could not be traced for follow-up, leaving 13,446 people in the study, 9,368 of them men (70%).

During the 1 year after hospital discharge, 121 of the 4,078 women died (3%) and 273 of the 9,368 men died (3%).

Both women and men who reported loneliness were more likely to have died:

  • women who felt lonely were almost 3 times more likely to have died than women who did not feel lonely (hazard ratio (HR) 2.92, 95% confidence interval (CI) 1.55 to 5.49)
  • men who felt lonely were about 2 times more likely to have died than men who did not feel lonely (HR 2.14, 95% CI 1.43 to 3.22)

At the time of discharge, both women and men who lived alone were less likely to have symptoms of anxiety, while women and men who felt lonely were more likely to have symptoms of anxiety.

People who felt lonely had worse health-related quality of life than those who did not feel lonely, while living alone was not linked to health-related quality of life.

Men living alone were more likely to have had another cardiac event, such as a heart attack, in the year following hospital discharge, compared to men living with others. However, living alone did not affect women's chances of having another cardiac event.

How did the researchers interpret the results?

The researchers said: "The subjective measure of loneliness was a much stronger predictor of both patient reported outcomes [such as anxiety and depression] and mortality compared with the objective measure of living alone."

They also said that "behavioural risk factors and comorbidity does not seem to explain the association between loneliness and morbidity and mortality", suggesting that the results are not just down to lonely people being more likely to live unhealthy lifestyles.

The researchers warned that loneliness in old age is becoming more common and said that it "should be a priority for public health initiatives", while doctors should include loneliness in "clinical risk assessment in cardiac patients".


This study does not prove that loneliness shortens life for heart patients. But it does suggest that there is something about loneliness that is linked to heart problems and length of life.

The problem is, because this is a cross-sectional study, we do not know whether people were lonely because of their health problems (which could make them more isolated) or whether their health problems resulted partly from loneliness.

The study took account of some potential confounding factors that could affect the results. But there are other factors that might affect the results, such as people's physical activity, medicines or cardiac risk, which were not included.

Another limitation is that almost half of the people surveyed did not return the questionnaire. People living alone were less likely to return the questionnaire. We do not know whether the results would have been the same if everyone had answered the questions.

It's important to make the distinction between feeling lonely and living alone. The study did not find a link between living alone and shorter life. Plenty of people who live alone have active social lives or are happy in their own company.

Loneliness, however, is a distressing condition that can lead to poor health behaviour, such as not eating properly and not being active. It can also lead to people becoming anxious or depressed. Alleviating loneliness is important, whether it affects length of life or not.

NHS Attribution