Table 2.
Age-Based Multilevel Models Examining Variables Related to Erectile Function and Sexual Satisfaction
| Variable | Model 1: erectile function | Model 2: sexual satisfaction | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| β (95% CI) | t | p | σ 2 | SE | β (95% CI) | t | p | σ 2 | SE | |
| Fixed effects | ||||||||||
| Time variable | ||||||||||
| Time-varying age at each wave (centered at 56) | −0.24 (−0.29, −0.19) | 10.33 | <.001 | −0.06 (−0.08, −0.03) | 3.96 | <.001 | ||||
| Time-invariant covariates predicting baseline level (β0it) | ||||||||||
| Age at baseline | 0.11 (0.07, 0.16) | 5.30 | <.001 | 0.02 (0.01, 0.03) | 3.62 | <.001 | ||||
| Race (Ref. = non-Hispanic White) | 0.13 (−0.01, 0.28) | 1.80 | .073 | 0.06 (−0.03, 0.15) | 1.40 | .162 | ||||
| Baseline erectile function | — | — | — | 0.09 (0.06, 0.11) | 6.40 | <.001 | ||||
| General cognitive ability at age 20 | −0.01 (−0.05, 0.03) | 0.29 | .775 | 0.01 (−0.02, 0.03) | 1.03 | .303 | ||||
| Time-variant covariates predicting outcomes over time (Yijt) | ||||||||||
| Incomea | −0.01 (−0.04, 0.03) | 0.13 | .900 | −0.02 (−0.05, −0.001) | 2.04 | .041 | ||||
| Committed status(Ref. = Partnered) | 0.16 (0.04, 0.28) | 2.58 | .010 | 0.14 (0.05, 0.23) | 3.04 | .002 | ||||
| Individual change in erectile function | — | — | — | 0.69 (0.65, 0.73) | 33.97 | <.001 | ||||
| Frequency of sexual activityb | 0.27 (0.25, 0.30) | 19.43 | <.001 | 0.18 (0.15, 0.22) | 10.14 | <.001 | ||||
| Depressive symptoms (CESD) | −0.05 (−0.09, −0.01) | 2.26 | .024 | −0.09 (−0.13, −0.06) | 5.64 | <.001 | ||||
| Physical function (SF-36) | 0.09 (0.04, 0.14) | 3.66 | <.001 | 0.02 (−0.02, 0.04) | 0.94 | .346 | ||||
| Number of CVDs | −0.03 (−0.07, 0.01) | 1.46 | .143 | 0.01 (−0.02, 0.04) | 0.56 | .573 | ||||
| Number of non-CVD medical conditions | −0.01 (−0.04, −0.03) | 0.50 | .616 | 0.01 (−0.01, 0.04) | 1.04 | .299 | ||||
| Alcohol consumptionc | 0.04 (−0.01, 0.08) | 1.92 | .055 | −0.02 (−0.05, 0.01) | 1.07 | .283 | ||||
| Current smoking status (Ref. = yes) | 0.20 (0.09, 0.31) | 3.57 | <.001 | 0.06 (−0.02, 0.14) | 1.42 | .155 | ||||
| Erectile dysfunction medications (Ref. = yes) | −0.31 (−0.38, −0.24) | 8.28 | <.001 | −0.04 (−0.09, 0.01) | 1.45 | .147 | ||||
| Random effects | ||||||||||
| Residual | 0.54 | .02 | 0.21 | .01 | ||||||
| Intercept | 0.05 | .02 | 0.08 | .01 | ||||||
| Time-varying age | <0.001 | <.001 | 0.002 | .01 |
Notes: Results in the first column represent a single age-based multilevel model predicting changes in erectile function over time from all row-listed variables. Results in the second column represent a single age-based multilevel model predicting changes in sexual satisfaction from all row-listed variables. Change in erectile function was calculated as erectile function at follow-up subtracted by an individual’s baseline value. CI = confidence interval; SE = standard error; CESD = Center for Epidemiological Studies; CVD = cardiovascular disease; Ref. = reference group; SF-36 = Short Form Quality-of-Life Questionnaire—36 Questions.
aAverage of an ordinal variable where 1 = <10,000; 2 = 10,000 to 19,999; 3 = 20,000 to 29,999; 4 = 30,000 to 39,999; 5 = 40,000 to 49,999; 6 = 50,000 to 59,999; 7 = 60,000 to 69,999, 8 = 70,000 to 79,999; 9 = 80,000 to 89,999; 10 = 90,000 to 99,999; 11 = 100,000 to 109,999; 12 = 110,000 to 119,999, 13 = 120,000 or more.
bAverage of an ordinal variable with responses of 1 (1–2 attempts), 2 (3–4 attempts), 3 (5–6 attempts), 4 (7–10 attempts), or 5 (11+ attempts).
cThe number of drinks consumed in the past 2 weeks.