TABLE 3—
Association of Severity and Health-Related Quality of Life With Socioeconomic Status, With and Without Adjustment for Potential Mediators: University of California, San Francisco Asthma Rhinitis Cohort, 2008–2009
| Severity of Asthma Score |
Rhinasthma HRQL |
|||||
| Models and Covariates | b (SE) | P | P(Sobel)a | b (SE) | P | P(Sobel)a |
| Income model (unadjusted) | ||||||
| Annual family income, $ (Ref: ≥ 100 000) | ||||||
| < 20 000 | 5.39 (0.83) | < .01 | 20.04 (1.81) | < .01 | ||
| 20 000 to < 40 000 | 4.52 (0.26) | < .01 | 14.33 (1.99) | < .01 | ||
| 40 000 to < 60 000 | 2.95 (0.94) | < .01 | 3.73 (0.85) | < .01 | ||
| 60 000 to < 80 000 | 2.08 (0.78) | < .01 | 4.71 (1.76) | < .01 | ||
| 80 000 to < 100 000 | 2.37 (0.38) | < .01 | 4.84 (2.15) | .03 | ||
| Income model (adjusted)b | ||||||
| Annual family income, $ (Ref: ≥ 100 000) | ||||||
| < 20 000 | 3.25 (1.10) | < .01 | 13.41 (2.53) | < .01 | ||
| 20 000 to < 40 000 | 3.41 (0.18) | < .01 | 10.11 (2.50) | < .01 | ||
| 40 000 to < 60 000 | 2.43 (0.87) | < .01 | 1.65 (1.19) | .17 | ||
| 60 000 to < 80 000 | 1.30 (0.85) | .13 | 2.00 (2.41) | .41 | ||
| 80 000 to < 100 000 | 1.95 (0.25) | < .01 | 3.06 (1.96) | .12 | ||
| Type of home (Ref: owner occupied) | ||||||
| Mobile home | −1.17 (0.93) | .21 | −3.26 (2.58) | .21 | ||
| Apartment, rented | 1.01 (0.53) | .06 | 2.04 (1.34) | .13 | ||
| Single family, rented | 3.60 (0.72) | < .01 | < .01 | 6.52 (3.21) | .04 | .01 |
| Carpet in bedroom | 0.24 (0.46) | .61 | 0.38 (2.03) | .85 | ||
| Gas heat (kitchen stove or space heater) | 0.40 (1.77) | .83 | 0.30 (5.44) | .95 | ||
| Smoke exposure (Ref: none) | ||||||
| Active smoking | −0.62 (1.01) | .54 | −2.12 (2.12) | .32 | ||
| Secondhand smoke only | 2.65 (0.39) | < .01 | .25 | 3.78 (4.39) | .39 | |
| Neighborhood-level exposures (0–5 score) | 0.33 (0.20) | .1 | 4.73 (1.02) | < .01 | .01 | |
| Education model (unadjusted) | ||||||
| Education (Ref: postgraduate education) | ||||||
| No high school degree | 3.40 (1.89) | .07 | 13.46 (5.57) | .02 | ||
| High school graduate | 2.12 (0.80) | < .01 | 4.31 (3.88) | .27 | ||
| Some college | 3.16 (0.97) | < .01 | 11.72 (2.13) | < .01 | ||
| Associate degree or trade school | 4.13 (1.23) | < .01 | 11.98 (1.79) | < .01 | ||
| Bachelor’s degree | 0.05 (0.38) | .9 | −1.34 (3.30) | .69 | ||
| Education model (adjusted)c | ||||||
| Education (Ref: postgraduate education) | ||||||
| No high school degree | 1.49 (1.76) | .4 | 7.07 (4.46) | .11 | ||
| High school graduate | 1.24 (0.71) | .08 | 1.91 (3.77) | .61 | ||
| Some college | 2.14 (0.52) | < .01 | 8.39 (1.81) | < .01 | ||
| Associate degree or trade school | 3.29 (0.93) | < .01 | 10.08 (2.56) | < .01 | ||
| Bachelor’s degree | −0.07 (0.17) | .67 | −1.46 (3.18) | .65 | ||
| Type of home (Ref: owner occupied) | ||||||
| Mobile home | −0.08 (0.80) | .92 | 1.02 (2.88) | .73 | ||
| Apartment, rented | 1.86 (0.85) | .03 | 4.90 (1.64) | < .01 | ||
| Single family, rented | 4.11 (0.50) | < .01 | < .01 | 8.92 (2.17) | < .01 | .01 |
| Carpet in bedroom | 0.29 (0.44) | .5 | 0.29 (2.07) | .89 | ||
| Gas heat (kitchen stove or space heater) | 0.43 (1.50) | .78 | 0.61 (5.00) | .91 | ||
| Smoke exposure (Ref: none) | ||||||
| Active smoking | −0.61 (1.00) | .54 | −2.16 (1.69) | .21 | ||
| Secondhand smoke only | 2.48 (0.05) | < .01 | .06 | 3.42 (2.63) | .19 | |
| Neighborhood-level exposures (0–5 score) | 0.45 (0.24) | .06 | 4.96 (1.00) | < .01 | .06 | |
Note. HRQL = health-related quality of life. Multiple linear regression models included age, gender, and all variables shown in tables. The sample size was n = 515.
a
Sobel tests for mediation conducted only on exposure variables that were significant (P < .05) in these models.
b
Model R2 for severity of asthma score = 0.15; model R2 for rhinasthma HRQL score = 0.16.
c
Model R2 for severity of asthma score = 0.16; model R2 for rhinasthma HRQL score = 0.17.