Prevalence of CPD among current smokers from 2002 to 2015 (The National Survey on Drug Use and Health, aged 12+)
| CPD | 2002* | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | Linear trend (13-year increment) | |
| Prevalence of CPD (weighted %) | Unadjusted OR(95% Cl) | T-test (p value) | ||||||||||||||
| Among current smokers by CPD | ||||||||||||||||
| 1–5 CPD (%) | 37.00 | 37.88 | 37.39 | 37.17 | 37.57 | 38.68 | 39.38 | 40.81 | 41.98 | 41.58 | 42.36 | 43.17 | 43.29 | 43.64 | 1.37 (1.30,1.45) | t=11.02 (0.0000) |
| 6–15 CPD (%) | 25.25 | 24.99 | 25.16 | 27.16 | 27.38 | 27.09 | 26.79 | 27.48 | 28.41 | 28.78 | 28.24 | 29.09 | 29.66 | 28.77 | 1.25 (1.18,1.32) | t=7.71 (0.0000) |
| 16 + CPD (%) | 37.75 | 37.12 | 37.45 | 35.66 | 35.05 | 34.23 | 33.83 | 31.71 | 29.61 | 29.64 | 29.41 | 27.74 | 27.05 | 27.59 | 0.58 (0.55,0.61) | t=−20.61 (0.0000) |
| (Unweighted N†) | 14 941 | 15 281 | 15 065 | 14 884 | 14 366 | 14 216 | 13 851 | 13 728 | 13 617 | 13 505 | 12 507 | 11 916 | 11 577 | 11 388 | ||
Logistic regressions were applied to examine the time trend within each particular group. An OR greater/less than 1 indicated a trend for the prevalence of CPD among each smoking category to increase/decrease during 2002–2015, and t tests showed the significance of time trends.
All current smokers are combination of current daily and non-daily smokers.
*2002 as reference year
†Missing number of CPD for 27–56 cases among current smokers.
CPD, number of cigarettes smoked per day in past 30 days.