Participants and Methods
Data from the 1999-2008 National Health and Nutrition Examination Survey were employed, with follow-up through 2011. Participants included 7441 adults aged 60 years and older (entry age for social support questions); 150 died during the first year of follow-up, leaving a study cohort of 7291 participants. Participants were asked, “Can you count on anyone to provide you with emotional support such as talking over problems or helping you make a difficult decision?” and “In the last 12 months, who was the most helpful in providing you with emotional support?” Sources evaluated include spouse, son, daughter, sibling, neighbor, co-worker, church member, professional, and friend. Regarding size of social network, participants were asked, “In general, how many close friends do you have?”
The median follow-up was 77 months (range, 12-153 months); 1818 deaths occurred in 593,467 person-months accrued, for an incidence rate of 3.06 deaths per 1000 person-months. In a Cox proportional hazards model (proportional assumption not violated [P=.62]; Harrell C statistic, 0.76) using survey-based procedures, only spousal support (3411 participants had spousal support; adjusted hazard ratio [HR], 0.77; 95% CI, 0.68-0.87) was associated with reduced all-cause mortality; covariates included age, sex, race/ethnicity, measured body mass index, total cholesterol level, physical activity (yes/no) in past 30 days, smoking status, and physician-diagnosed congestive heart failure, coronary artery disease, stroke, cancer, hypertension, and diabetes.
Regarding size of social network, compared with those who had 0 close friends (n=302), those with 1 to 2 close friends (n=1285; adjusted HR, 0.67; 95% CI, 0.50-0.90), 3 to 4 close friends (n=1489; adjusted HR, 0.73; 95% CI, 0.55-0.98), 5 close friends (n=961; adjusted HR, 0.70; 95% CI, 0.52-0.93), and 6 or more close friends (n=3254; adjusted HR, 0.62; 95% CI, 0.46-0.83) had a reduced risk of all-cause mortality; results were unchanged when we excluded participants with the aforementioned comorbid illnesses.