Men and women who "feel lonely" are more likely to have worse mental health, heart disease conditions and die early than those "living alone", according to a study.
The findings showed that loneliness was associated with a doubled mortality risk in women and nearly doubled risk in men.
Both men and women who felt lonely were three times more likely to report symptoms of anxiety and depression, and had a significantly lower quality of life than those who did not feel lonely.
"Loneliness is a strong predictor of premature death, worse mental health, and lower quality of life in patients with cardiovascular disease, and a much stronger predictor than living alone, in both men and women," said Anne Vinggaard Christensen, doctoral student, at the Copenhagen University Hospital.
The results were presented at the annual nursing congress EuroHeartCare 2018 in Dublin.
The study investigated whether poor social network was associated with worse outcomes in 13,463 patients with ischaemic heart disease, arrhythmia (abnormal heart rhythm), heart failure, or heart valve disease.
Feeling lonely was associated with poor outcomes in all patients regardless of their type of heart disease, and even after adjusting for age, level of education, other diseases, body mass index, smoking, and alcohol intake.
People with poor social support may have worse health outcomes because they have unhealthier lifestyles, are less compliant with treatment, and are more affected by stressful events.
But, when "we adjusted for lifestyle behaviours and many other factors in our analysis, we still found that loneliness is bad for health," Christensen said.
According to European guidelines on cardiovascular prevention, people who are isolated or disconnected from others are at increased risk of developing and dying prematurely from coronary artery disease.
The guidelines recommend assessment of psychosocial risk factors in patients with established cardiovascular disease and those at high risk of developing cardiovascular disease.