Individuals with adequate social relationships have a 50% greater likelihood（可能性） of survival compared to those with poor or insufficient social relationships. The magnitude（大小，量级） of this effect is comparable with stopping smoking and exceeds（超过，胜过） many well known risk factors for mortality such as obesity and physical inactivity. These are the main findings of a meta-analysis of social relationships and mortality risk conducted by Julianne Holt-Lunstad (Brigham Young University, Utah, USA) and colleagues and published in this week's PLoS Medicine. The authors' findings are derived from the identification and analysis of 148 studies that included data from 308,849 individuals who were followed up for an average of 7.5 years. Their analysis indicates that the overall effect remained consistent despite taking various factors, such as age, sex, initial health status, follow up period and cause of death, into account. This result suggests that the association between social relationships and mortality may be general, therefore, efforts to reduce risk should not be isolated to certain groups, such as older people.

Efforts to reduce mortality via enhancing social relationship factors will require innovation but any future social relationship-based interventions represent a major opportunity to enhance both survival and quality of life, say the authors.

The authors conclude that "Physicians, health professionals, educators, and the public media take risk factors, such as smoking, diet, and exercise, seriously: the data presented here make a compelling（引人注目的，强制的） case for social relationship factors to be added to that list."