Table 3.
| Loneliness and Social Isolation |
|||
|---|---|---|---|
| Group 1 (Reference) | Loneliness Group 3 vs. Bottom Group 1 (n = 1824) RR/OR/β (95% CI) | Social Isolation Group 3 vs. Bottom Group 1 (n = 1800) RR/OR/β (95% CI) | |
| Physical Health | |||
| All-cause mortality | 1.00 | 1.43 (1.17, 1.76)*** | 1.74 (1.25, 2.42)** |
| Number of chronic conditions | 0.00 | 0.03 (−0.02, 0.09) | 0.00 (−0.05, 0.05) |
| Diabetes | 1.00 | 0.99 (0.87, 1.14) | 0.92 (0.79, 1.08) |
| Hypertension | 1.00 | 1.02 (0.94, 1.10) | 1.00 (0.91, 1.11) |
| Stroke | 1.00 | 1.11 (0.90, 1.36) | 1.30 (1.01, 1.67)* |
| Cancer | 1.00 | 1.04 (0.89, 1.22) | 0.88 (0.73, 1.07) |
| Heart disease | 1.00 | 1.01 (0.90, 1.14) | 1.00 (0.86, 1.16) |
| Lung disease | 1.00 | 1.25 (1.04, 1.51)* | 1.20 (0.93, 1.55) |
| Arthritis | 1.00 | 1.03 (0.94, 1.11) | 1.02 (0.92, 1.12) |
| Overweight/obesity | 1.00 | 0.97 (0.90, 1.05) | 0.95 (0.86, 1.06) |
| Physical functioning limitations | 1.00 | 1.26 (1.11, 1.45)*** | 1.38 (1.18, 1.62)*** |
| Cognitive impairment | 1.00 | 1.10 (0.94, 1.29) | 1.22 (1.02, 1.46)* |
| Chronic pain | 1.00 | 1.13 (1.02, 1.25)* | 1.05 (0.92, 1.20) |
| Self-rated health | 0.00 | −0.12 (−0.20, −0.05)** | −0.05 (−0.12, 0.02) |
| Health Behaviors | |||
| Heavy drinking | 1.00 | 0.89 (0.62, 1.27) | 0.95 (0.57, 1.59) |
| Smoking | 1.00 | 0.99 (0.81, 1.21) | 1.28 (0.87, 1.88) |
| Frequent physical activity | 1.00 | 0.94 (0.85, 1.03) | 0.87 (0.77, 0.97)* |
| Sleep problems | 1.00 | 1.16 (1.04, 1.29)** | 1.03 (0.90, 1.17) |
| Psychological Well-being | |||
| Positive affect | 0.00 | −0.39 (−0.48, −0.31)*** | −0.27 (−0.35, −0.20)*** |
| Life satisfaction | 0.00 | −0.38 (−0.46, −0.30)*** | −0.21 (−0.30, −0.11)*** |
| Optimism | 0.00 | −0.38 (−0.49, −0.26)*** | −0.20 (−0.31, −0.10)** |
| Purpose in life | 0.00 | −0.37 (−0.43, −0.31)*** | −0.21 (−0.29, −0.13)*** |
| Mastery | 0.00 | −0.28 (−0.34, −0.22)*** | −0.04 (−0.12, 0.04) |
| Health mastery | 0.00 | −0.10 (−0.17, −0.02)* | −0.09 (−0.20, 0.01) |
| Financial mastery | 0.00 | −0.24 (−0.31, −0.16)*** | −0.12 (−0.24, 0.00) |
| Psychological Distress | |||
| Depression | 1.00 | 2.65 (2.00, 3.51)*** | 1.36 (1.04, 1.78)* |
| Depressive symptoms | 0.00 | 0.34 (0.27, 0.41)*** | 0.13 (0.03, 0.23)* |
| Hopelessness | 0.00 | 0.35 (0.24, 0.46)*** | 0.18 (0.08, 0.28)*** |
| Negative affect | 0.00 | 0.39 (0.29, 0.50)*** | 0.07 (−0.02, 0.17) |
| Perceived constraints | 0.00 | 0.33 (0.24, 0.42)*** | 0.12 (0.03, 0.22)* |
| Social Factors | |||
| Loneliness | 0.00 | 0.95 (0.90, 1.01)*** | 0.38 (0.27, 0.49)*** |
| Social Isolation | 0.00 | 0.15 (0.13, 0.18)*** | 0.57 (0.52, 0.62)*** |
Abbreviations: CI, confidence interval; OR, odds ratio; RR, risk ratio.
*p < 0.05 before Bonferroni correction; **p < 0.01 before Bonferroni correction; ***p < 0.05 after Bonferroni correction (the p-value cut-off for Bonferroni correction is p = 0.05/32 outcomes = p < 0.0015625).We marked multiple p-value cutoffs in the table and confidence intervals, because multiple testing practices vary widely, and this is an evolving area of research.
If the reference value is “1,” the effect estimate is OR or RR; if the reference value is “0,” the effect estimate is β.
The analytic sample was restricted to those who had participated in the baseline wave (t1;2012 or 2014). Multiple imputation was performed to impute missing data on the exposure, covariates, and outcomes. All models adjusted for sociodemographic characteristics (age, sex, race/ethnicity, annual household income, total wealth, level of education, employment status, health insurance, geographic region), pre-baseline childhood abuse, pre-baseline values of the outcome variables (diabetes, hypertension, stroke, cancer, heart disease, lung disease, arthritis, overweight/obesity, physical functioning limitations, cognitive impairment, chronic pain, self-rated health, heavy drinking, current smoking status, physical activity, sleep problems, positive affect, optimism, purpose in life, mastery, health mastery, financial mastery, depressive symptoms, hopelessness, negative affect, perceived constraints), and personality factors (openness, conscientiousness, extraversion, agreeableness, neuroticism). These variables were adjusted for in the pre-baseline wave (t1;2012 or 2014).
We used an outcome-wide analytic approach and ran a separate model for each outcome. We also ran a different type of model depending on the nature of the outcome: 1) for each binary outcome with a prevalence of ≥10%, we ran a generalized linear model with a log link and Poisson distribution to estimate a RR; 2) for each binary outcome with a prevalence of <10%, we ran a logistic regression model to estimate an OR; and 3) for each continuous outcome, we ran a linear regression model to estimate a β.
All continuous outcomes were standardized (mean = 0, standard deviation = 1), and β was the standardized effect size.
Without reference points and benchmarks, it is difficult to interpret effect sizes. Thus, we included loneliness and social isolation as outcomes so that readers can use the effect sizes as mental reference points to evaluate the effect sizes between loneliness and social isolation with the other health and well-being outcomes.
Loneliness and social isolation were examined as separate independent variables in all models. Thus, they were not included simultaneously in the same model.