Table 5.
Prevalence of depression among current, former and never smokers by family income (NSDUH, 2005–2013, aged 12+)
| Family income | 2005* | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | Linear Trend | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Prevalence of depression in past year stratified by family income (%, s.e.) | Unadjusted OR (95%CI) |
t-test (p- value) |
Adjusted ORb, c (95%CI) |
t-test (p- value) |
|||||||||
| Current smokersa | |||||||||||||
| <$20,000 (%) | 14.04 | 12.49 | 13.45 | 12.70 | 14.27 | 13.30 | 14.50 | 14.14 | 12.14 | 1.00 (0.98,1.02) |
t=0.02 (0.9826) |
1.00 (0.98,1.02) |
t=0.36 (0.7212) |
| s.e. | (0.71) | (0.84) | (0.94) | (0.92) | (0.93) | (0.86) | (1.05) | (0.84) | (0.71) | ||||
| $20,000–$74,999 (%) | 9.54 | 10.12 | 10.43 | 10.02 | 9.76 | 9.74 | 10.50 | 10.41 | 10.25 | 1.01 (0.99,1.02) |
t=0.84 (0.4039) |
1.01 (1.00,1.03) |
t=1.50 (0.1378) |
| s.e. | (0.55) | (0.39) | (0.57) | (0.52) | (0.51) | (0.57) | (0.55) | (0.60) | (0.64) | ||||
| >=$75,000 (%) | 6.36 | 7.78 | 8.06 | 8.25 | 8.41 | 9.48 | 7.71 | 7.42 | 8.91 | 1.02 (1.00,1.05) |
t=1.73 (0.0893) |
1.03 (1.00,1.05) |
t=2.10 (0.0400) |
| s.e. | (0.63) | (0.76) | (0.84) | (0.68) | (0.78) | (0.78) | (0.69) | (0.71) | (0.73) | ||||
| Differential time trend among current smokers: year as continuous×family income | F(2)=1.11(0.3371) | F(2)=0.91(0.4061) | |||||||||||
| Former smokers | |||||||||||||
| <$20,000 (%) | 7.45 | 7.58 | 8.06 | 10.06 | 8.61 | 8.27 | 10.81 | 10.33 | 9.75 |
1.04 (1.01,1.08) |
t=2.51 (0.0147) |
1.05 (1.01,1.08) |
t=2.51 (0.0149) |
| s.e. | (0.74) | (0.87) | (1.04) | (1.32) | (0.99) | (1.02) | (1.10) | (0.92) | (0.91) | ||||
| $20,000–$74,999 (%) | 5.49 | 4.62 | 6.54 | 6.34 | 6.73 | 7.09 | 5.67 | 5.87 | 6.95 |
1.03 (1.00,1.05) |
t=2.32 (0.0237) |
1.03 (1.01,1.06) |
t=2.92 (0.0049) |
| s.e. | (0.42) | (0.36) | (0.42) | (0.56) | (0.54) | (0.48) | (0.37) | (0.46) | (0.53) | ||||
| >=$75,000 (%) | 4.43 | 4.84 | 4.77 | 3.90 | 4.96 | 4.21 | 4.85 | 4.23 | 5.27 | 1.01 (0.98,1.04) |
t=0.56 (0.5797) |
1.01 (0.98,1.05) |
t=0.89 (0.3763) |
| s.e. | (0.49) | (0.47) | (0.40) | (0.41) | (0.55) | (0.47) | (0.46) | (0.54) | (0.54) | ||||
| Differential time trend among former smokers: year as continuous×family income | F(2)=1.13(0.3299) | F(2)=0.82(0.4447) | |||||||||||
| Never smokers | |||||||||||||
| <$20,000 (%) | 6.93 | 5.07 | 5.38 | 6.66 | 5.38 | 5.19 | 6.30 | 8.46 | 7.10 |
1.03 (1.00,1.07) |
t=2.14 (0.0364) |
1.03 (1.00,1.06) |
t=1.99 (0.0513) |
| s.e. | (0.85) | (0.54) | (0.53) | (0.80) | (0.48) | (0.48) | (0.69) | (0.88) | (0.78) | ||||
| $20,000–$74,999 (%) | 5.21 | 5.10 | 4.80 | 5.63 | 4.71 | 5.08 | 4.46 | 5.49 | 5.52 | 1.00 (0.99,1.02) |
t=0.47 (0.6384) |
1.01 (0.99,1.03) |
t=0.72 (0.4749) |
| s.e. | (0.38) | (0.39) | (0.32) | (0.42) | (0.33) | (0.36) | (0.34) | (0.37) | (0.39) | ||||
| >=$75,000 (%) | 3.45 | 3.96 | 4.00 | 3.76 | 4.14 | 4.68 | 4.79 | 5.31 | 4.61 |
1.05 (1.02,1.07) |
t=4.02 (0.0002) |
1.05 (1.03,1.08) |
t=4.54 (<0.0001) |
| s.e. | (0.41) | (0.40) | (0.43) | (0.35) | (0.42) | (0.49) | (0.37) | (0.48) | (0.36) | ||||
| Differential time trend among never smokers: year as continuous×family income | F(2)=4.10(0.0214) | F(2)=4.48(0.0153) | |||||||||||
| Differential time trend: year as continuous×smoking (current vs. never smokers: current vs. former smokers) among each family income category |
Unadjusted | Adjusted | |||||||||||
| Differential time trend among <$20,000: year×smoking (current vs. never smokers) | F(1)=2.60(0.1124) | F(1)=1.84(0.1804) | |||||||||||
| Differential time trend among $20,000–74,999: year×smoking (current vs. never smokers) | F(1)=0.03(0.8584) | F(1)=0.13(0.7213) | |||||||||||
| Differential time trend among >=75,000: year×smoking (current vs. never smokers) | F(1)=2.03(0.1593) | F(1)=2.46(0.1220) | |||||||||||
| Differential time trend among <$20,000: year×smoking (current vs. former smokers) | F(1)=5.06(0.0282) | F(1)=3.96(0.0512) | |||||||||||
| Differential time trend among $20,000–74,999: year×smoking (current vs. former smokers) | F(1)=2.25(0.1389) | F(1)=2.32(0.1332) | |||||||||||
| Differential time trend among >=75,000: year×smoking (current vs. former smokers) | F(1)=0.34(0.5623) | F(1)=0.41(0.5266) | |||||||||||
Logistic regressions were applied to examine the time trend within each particular group. An odds ratio greater/less than one indicated a significant trend for the prevalence of depression among each smoking category stratified by family income to increase/decrease during 2005–2013, and t tests showed the significance of time trends.
a
who smoked in the past 12 months
b
Odds ratios are for past year depression versus no past year depression.
c
Adjusted models: were adjusted for age (12–17, 18–25, 26–34, 34–49, 50+ or older) and gender (male, female).
*
2005 as a reference year
s.e. - standard error
CI, confidence interval; OR, odds ratio; NSDUH, National Survey on Drug Use and Health; s.e., standard error