In his recent paper published in the journal 'Addiction' Robert West and colleagues tried to count the number of additional people who successfully quit smoking in 2014 and would not have done so if ecigs didn't exist.You can read the paper here. The conclusions drawn in this analysis have prompted a great deal of debate.
Suppose in year 1 we have 1000 people attempting to quit smoking of whom 100 are successful. 20 of those people used method A, 30 use method B, and 50 use method C. In year 2 method D is introduced, and now 10 people succeed by using method A, 20 use method B, 30 use method C and 40 use method D. Method D is the most popular method, but it hasn't added to the numbers, we still only have 100 successful quitters.
However, suppose instead in year 2, 15 use A, 25 use B, 35 use C and 40 use D. Now we have 115 successful quitters. Although 40 quitters used D, only 15 of them are additional. The rest have been 'poached' from other methods. However, some of the 'poached' quitters may not have used (say) method A in any case - it could be that factors other than the existence of D made A less popular for (say) 2 people than it had been previously - in which case the additional quitters attributable to D would be 17.
So how did Robert West do it?
891K people used ecigs in their quit attempt in 2014. There aren't enough good data to tell us directly how many of these would have been successful long term (12 months) quitters. We do know (from other studies) that the long term quit rates for both over the counter (OTC) NRT and cold turkey (CT) are 5%, and that ecigs increase the success rate over these for any quit attempt by 50%. So 5% of our 891K ecig quitters would likely quit with OTC NRT or CT if e-cigarettes weren't available and 2.5% would not. 2.5% of 891K is 22K. These are the people who would not have quit if they had bought OTC NRT or gone cold turkey but did so with ecigs.
But what about the ones 'poached' from medicinal methods (prescription meds and Stop Smoking Services)?
In 2014 the medicinal methods 'lost' 330K quit attempts, 250K of which are attributed to people choosing ecigs instead rather than just rejecting the med options. So to account for those we have to deduct them from our 891K ecig quit attempters (because they would have gone the meds route if ecigs were unavailable). So now our starting number is 641K. 2.5% of 641K is 16K. These are the people who would not have quit in 2014 if ecigs were not available.
Well that looks like an awfully small figure doesn't it?
In reality, using Roberts figures, 891K people used e-cigarettes in a quit attempt and of those, 66.8K (7.5%) could be expected to be successful long term. That is a huge number of people who have, at no cost to the state, given up smoking by finding a solution which suited them. 16K of those people would not have given up had ecigs not been available. They either would not have chosen, or would not have succeeded via any other route.
The 50% uplift in the success rate of ecigs compared with OTC NRT is from a 2014 study which aggregated data collected from July 2009 to February 2014 via household surveys (the same uplift was reported when 2009 -2011 respondents were excluded). It will therefore mostly include data from time periods when e-cigarettes were nowhere near as efficient, available or socially acceptable as they are now. In addition vapers, including new switchers, are now migrating from cigalike type products to more efficient refillable tank systems. It seems likely then that a comparison made now using current devices would produce a much larger uplift. For example, if in 2014 ecigs were 100% better than OTC NRT and CT rather than 50% (i.e. they had a 10% success rate rather than 7.5%) our quit attempters would have achieved 89K successful quits in that year, 32K of which would be people who would not have quit if ecigs didn't exist.
That is nothing to be sniffed at and is probably still a cautious estimate. If only the science could keep up.
So why don't these figures look like ASH's?
Because whereas these figures look at quit attempts and successes using a particular method in a particular year, all ASH does is count absolute numbers of vapers and dual users at a single point in time. ASHs figure for exclusive vapers includes people who switched in other years, people who used other methods to quit then started vaping and even a tiny smattering of people who never quit at all because they didn't smoke. ASHs figures don't include people who vaped then became totally abstinent or relapsed to smoking, whereas these figures do. Comparing the two data sets is like comparing apples with elephants.
Ultimately, it shouldn't matter whether ecigs are responsible for 16K, 32K or a million additional quitters per year. Vapers are almost exclusively ex smokers who, whether it be for health, pleasure or some other vagary of personal choice, have abandoned smoking tobacco for something which is at least 95% safer for themselves and harms no one else. Every single one of them is a cause for celebration.