Friday 18 November 2016

The missing smokers

A cheer went out when Health Canada released the results of the Canadian Tobacco, Alcohol and Drugs Survey (CTADS) for 2015.

The number of people who identify themselves as smokers in Canada had fallen to an all-time low -- only 3.8 million smokers representing only 13% of the population. If we consider only those who smoke on a daily basis, the results were even more encouraging: fewer than 10% said that they lit up ever day. This is one of the lowest rates among developed countries - lower than the rates observed for any OECD country!

But is it maybe too good to be true?  


The CTADS is a relatively recent survey. It was developed a few years ago when the (former) government decided to reduce its investment in monitoring tobacco use, and decided to compress the annual Canadian Tobacco Use Monitoring Survey (CTUMS) into a bi-annual survey which also covered other sin behaviours, like drinking and drug use. 

Meanwhile, Statistics Canada continues to manage a far larger survey which produces much higher estimates of smoking.  The Canadian Community Health Survey (CCHS) covers a wide range of health behaviours, of which tobacco use is a regular but small component. CTADS gets responses from 15,000 Canadians every 2 years: the CCHS covers 120,000 individuals. Two thirds of those asked to participate in the CCHS agree to do so (an overall response rate of 66%). Fewer than half of those asked to participate in the CTADS agree to do so (an overall response rate of 48%).

Even though they use the same questions, the CCHS has always produced higher estimates of smoking behaviour than either CTUMS and CTADS. 

It may now be that the gap between the results of these surveillance tools is growing. The 1.6 million fewer smokers identified by CTADS in 2015 than by CCHS in 2014 represents about 40% more smokers. This is a big difference.

We may not have to wait much longer to learn of the CCHS estimates for 2015. Information on risk factors for heart disease are scheduled for release on December 12, 2016.

Perhaps we can leave the champagne on ice for a while.

Canadian Tobacco Use Monitoring Survey (CTUMS)
Canadian Community Health
Survey (CCHS)
Smokers #
%
95% CI
Smokers
%
95% CI
1999
6,121,992
25
2000
6,007,562
24
2001
5,411,822
22
6,677,856
26
25.5-26.4
2002
5,414,335
21
2003
5,332,326
21
20.0-21.8
6,080,504
23
22.7-23.4
2004
5,116,200
20
18.5- 0.7
2005
4,966,600
19
17.6-19.8
5,874,689
22
21.4-22.1
2006
4,934,022
19
17.6-19.6
2007
5,176,302
19
18.2-20.2
6,112,442
22
21.6-22.5
2008
4,880,488
18
16.8-18.9
6,009,311
21
20.9-21.9
2009
4,851,274
18
16.5-18.6
5,730,321
20
19.6-20.7
2010
4,701,868
17
15.8-17.7
5,967,259
21
20.2-21.3
2011
4,910,520
17
16.2-18.4
5,764,843
20
19.3-20.4
2012
4,629,987
16
15.0-17.3
5,933,095
20
19.6-20.9
Canadian Tobacco, Alcohol and Drugs Survey
2013
4,233,300
14.6
13.5-15.8
5,722,635
19
18.7-19.9
2014
5,400,000
18
17.5-18.6
2015
3,846,800
13
11.9-14