Table 2.
Multivariate Cox hazard models for the association between loneliness and the new-onset of ADL and IADL disabilitiesa
| Variables | Event = ADL disability | Event = IADL disability | ||||||
|---|---|---|---|---|---|---|---|---|
| Model 1 | Model 2 | Model 1 | Model 2 | |||||
| HR (95% CI) | Wald χ2 (p-value)b | HR (95% CI) | Wald χ2 (p-value)b | HR (95% CI) | Wald χ2 (p-value)b | HR (95% CI) | Wald χ2 (p-value)b | |
| Loneliness (ref. no loneliness) | ||||||||
| Transient loneliness | 1.17 (0.88,1.57) | 1.10 (0.273) | 1.15 (0.87,1.51) | 0.96 (0.337) | 1.16 (0.97,1.39) | 1.59 (0.112) | 1.12 (0.99,1.26) | 1.71 (0.090) |
| Incident loneliness | 1.33 (1.12,1.59) | 3.22 (0.001) | 1.35 (1.01,1.80) | 3.18 (0.002) | 1.26 (1.04,1.52) | 2.40 (0.017) | 1.20 (1.01,1.43) | 2.09 (0.036) |
| Chronic loneliness | 1.37 (1.16,1.63) | 3.60 (<0.001) | 1.36 (1.14,1.62) | 3.54 (<0.001) | 1.25 (1.09,1.44) | 3.17 (0.002) | 1.26 (1.10,1.44) | 3.19 (0.002) |
| Age (years) | 1.07 (1.07,1.08) | 18.64 (<0.001) | 1.07 (1.07,1.08) | 18.60 (<0.001) | 1.09 (1.08,1.10) | 22.38 (<0.001) | 1.09 (1.08,1.10) | 22.34 (<0.001) |
| Women | 0.94 (0.84,1.06) | 0.07 (0.946) | 0.98 (0.84,1.13) | 0.06 (0.951) | 0.92 (0.81,1.04) | 1.92 (0.055) | 0.92 (0.79,1.07) | 1.51 (0.132) |
| Race/ethnicity (ref. Non- Hispanic White) | ||||||||
| Non-Hispanic Black | 1.09 (0.91,1.31) | 1.42 (0.155) | 1.09 (0.91,1.32) | 1.42 (0.156) | 1.05 (0.86,1.27) | 0.41 (0.684) | 1.05 (0.86,1.27) | 0.41 (0.683) |
| Hispanic | 0.92 (0.73,1.15) | 1.16 (0.245) | 0.92 (0.73,1.15) | 1.17 (0.241) | 0.95 (0.75,1.19) | 0.21 (0.832) | 0.95 (0.75,1.19) | 0.21 (0.834) |
| Others | 1.17 (0.80, 1.69) | 0.04 (0.967) | 1.16 (0.80,1.68) | 0.05 (0.958) | 0.93 (0.61,1.43) | 0.45 (0.655) | 0.93 (0.61,1.43) | 0.45 (0.652) |
| Education (ref. 0–11 school years) | ||||||||
| 12 years | 0.72 (0.61,0.84) | 3.23 (0.001) | 0.72 (0.61,0.84) | 3.24 (0.001) | 0.78 (0.67,0.92) | 3.32 (0.001) | 0.78 (0.67,0.92) | 3.32 (0.001) |
| 13+ years | 0.78 (0.67,0.92) | 3.23 (0.001) | 0.78 (0.67,0.92) | 3.24 (0.001) | 0.79 (0.67,0.93) | 3.20 (0.001) | 0.79 (0.67,0.93) | 3.21 (0.001) |
| Household income (ref. 1st quartile) | ||||||||
| 2nd quartile | 0.99 (0.85,1.15) | 0.77 (0.441) | 0.99 (0.85,1.15) | 0.76 (0.445) | 0.98 (0.84,1.14) | 0.80 (0.423) | 0.98 (0.84,1.14) | 0.80 (0.423) |
| 3rd quartile | 0.90 (0.76,1.08) | 0.74 (0.460) | 0.90 (0.76,1.08) | 0.74 (0.462) | 0.80 (0.67,0.96) | 2.70 (0.007) | 0.80 (0.67,0.96) | 2.70 (0.007) |
| 4th quartile | 0.87 (0.71,1.07) | 1.61 (0.108) | 0.87 (0.71,1.06) | 1.61 (0.107) | 0.86 (0.70,1.05) | 1.95 (0.052) | 0.86 (0.70,1.05) | 1.94 (0.052) |
| Married | 0.97 (0.84,1.12) | 0.17 (0.866) | 0.97 (0.84,1.12) | 0.18 (0.860) | 0.88 (0.76,1.02) | 1.56 (0.120) | 0.88 (0.76,1.02) | 1.56 (0.119) |
| Current smoker | 1.61 (1.36,1.91) | 4.67 (<0.001) | 1.61 (1.36,1.91) | 4.67 (<0.001) | 1.57 (1.31,1.88) | 5.51 (<0.001) | 1.57 (1.31,1.88) | 5.51 (<0.001) |
| Current heavy drinker | 0.89 (0.75,1.06) | 0.72 (0.472) | 0.89 (0.75,1.06) | 0.72 (0.470) | 0.88 (0.74,1.04) | 1.30 (0.193) | 0.88 (0.74,1.04) | 1.30 (0.194) |
| CESD | 1.12 (1.07,1.16) | 5.67 (<0.001) | 1.12 (1.07,1.16) | 5.67 (<0.001) | 1.07 (1.02,1.11) | 3.72 (<0.001) | 1.07 (1.02,1.11) | 3.71 (<0.001) |
| Self-reported health | 1.35 (1.26,1.44) | 9.16 (<0.001) | 1.35 (1.26,1.44) | 9.17 (<0.001) | 1.34 (1.25,1.44) | 8.67 (<0.001) | 1.34 (1.25,1.44) | 8.67 (<0.001) |
| Having hypertension | 1.07 (0.95,1.21) | 0.90 (0.370) | 1.07 (0.95,1.21) | 0.90 (0.366) | 1.12 (0.99,1.26) | 1.72 (0.086) | 1.12 (0.99,1.26) | 1.72 (0.086) |
| Having diabetes | 1.25 (1.09,1.44) | 3.17 (0.002) | 1.25 (1.09,1.44) | 3.16 (0.002) | 1.21 (1.05,1.39) | 2.72 (0.007) | 1.21 (1.05,1.39) | 2.71 (0.007) |
| Having heart diseases | 1.04 (0.91,1.18) | 1.19 (0.236) | 1.04 (0.91,1.18) | 1.16 (0.246) | 1.05 (0.92,1.20) | 0.79 (0.429) | 1.05 (0.92,1.20) | 0.79 (0.431) |
| Women × Transient loneliness | 1.08 (0.76,1.53) | 0.44 (0.661) | 1.07 (1.01, 1.14) | 2.71 (0.007) | ||||
| Women × Incident loneliness | 0.99 (0.69,1.42) | 0.06 (0.953) | 1.07 (0.68,1.47) | 0.70 (0.420) | ||||
| Women × Chronic loneliness | 1.00 (0.73,1.37) | 0.00 (0.999) | 1.11 (1.02,1.20) | 2.37 (0.019) | ||||
Note:
a
Cox proportional hazard regression models were applied to estimated hazard ratios (HRs) of ADL/IADL disability. All p-values for the overall test less than 0.001.
b
P-values were based on Wald χ2 tests with one degree of freedom.
Model 1: added loneliness subgroups and adjusted to age, sex, race/ethnicity, education, income, marital status, smoking, drinking, depression, self-rated health, and comorbidities. Model 2: Model 1 plus the interaction between sex and loneliness.
Abbreviations: CI = Confidence Interval; ADL = Activities of Daily Living; IADL = Instrumental Activities of Daily Living; CESD = Center for Epidemiologic Studies Depression Scale score without the loneliness item.