1 University College London February 2014 Robert West Population impact of tobacco dependence treatment

Declaration of interest I receive research funds and undertake consultancy for companies that develop and manufacture smoking cessation medications (Pfizer and J&J) I am co-director of the UK National Centre for Smoking Cessation and Training I am a trustee of the stop-smoking charity, QUIT My salary is funded by the charity, Cancer Research UK 2

Treatment for tobacco dependence –Clinical interventions that aim to promote tobacco cessation Medication/NRT (bought ‘over the counter’ and provided by health professional) Behavioural support provided face-to-face, by telephone, text messaging, internet, mobile applications or books Population impact –Effect of an intervention over a defined time period in reducing Number and percentage of tobacco users Tobacco-related harm Definitions 3

In a country of 43 million adults such as England –prevalence reduction of as little as 0.2% = 86,000 non-smokers If quitting occurs on average in middle age 1 –leads to 600 lives saved annually Impact is likely to be greater –heavier, high risk smokers seek help with quitting What is a significant population impact? 4 1 Doll et al (2004) BMJ

Survey sample sizeConfidence interval around 25% 1000±2.7% 5,000±1.2% 10,000±0.9% 20,000±0.6% 50,000±0.4% What is a measurable population impact? 5 0.2% prevalence reduction is not measurable by surveys Just because something is not directly measurable, it does not mean it is not important

Requires estimation and modelling using best available data –smoking prevalence –estimates of rates of factors that increase and decrease numbers of smokers –unaided success rate of quit attempts –proportion of smokers using a given treatment annually –estimated ‘real world’ effect of the treatment estimated from studies in countries with good data How to assess population impact in the absence of prevalence survey data 6

An Excel model of ‘inflow’ and ‘outflow’ of cigarette smokers in the population 1 Based primarily on data from the Smoking Toolkit Study: monthly surveys of representative samples of smokers and recent ex-smokers Estimating population impact in England: the Smoking Pipe Model 7 1 West (2013) Smoking Pipe Model (STS documents)

‘Smoking Pipe’ model 8 Smokers turn 16 Start smoking post-16 Prior quitters relapse Attempt to stop Relapse Die Smokers Excludes migration as effects are very small

Key behaviours during Smoking prevalence at 16:13% 2.Uptake rate post 16:4% per year of age 3.Quit attempt rate during the year: 34.4% 4.Relapse rate during the year: 82.4% 5.Relapse rate from past quitters: 1% 9

‘Smoking Pipe’ model for England: year olds 83,000 Uptake149,000 Late relapse 61,000 Attempt to quit 3,067,000 2,589,000 relapse 92,000 Die Prevalence reduction 0.75% 540,000 stop From: The Smoking Pipe Model, Adult population: 43 million Smokers at start: 8.9 million Prevalence at start: 20%

Relative contribution of different influences on prevalence change 11

Relative contribution of different influences on prevalence change: a closer look 12

Percentage of smokers trying to stop who use different methods 13

14 Real world effectiveness of different methods Significantly better than no aid adjusting for confounding variables, p<0.001 Kotz et al (2013) Addiction, Online early

Enter parameters for –Population size –Untreated quit attempt rate –Unaided quit success rate –Effect of cessation on mortality –Net effect on prevalence of uptake and death –Effect of treatment on quit attempt rate –Effect of treatment on success rate Estimated population effect of treatment over 10 years: an Excel model 15

GPs paid to give brief advice National stop-smoking service treating 700,000 smokers per year with behavioural support and medication Smoking prevalence at start of 2012: 21% Almost no tobacco use in non-smokers England 16

Prevalence impact of treatment in England 17 Actual: Brief advice causes 4% to try to quit. 26% treatment uptake Enhanced: Brief advice causes 10% to try to quit, 50% treatment uptake

Cumulative impact of treatment on mortality in England 18

Very little smoking cessation infrastructure Evidence from new RCT (Sarkar et al, in preparation) –Brief advice by outreach in poor urban areas can increase quit attempt rate by 2% –Background quit rate 0.5% Mixed tobacco use prevalence: 35% India 19

Prevalence impact of brief advice in India 20

Cumulative impact of treatment on mortality of brief advice in India 21

It is unrealistic to expect to be able to detect important effects of smoking cessation treatment on prevalence reduction by surveys It is possible to estimate treatment impact where data are available on prevalence of treatment provision and use When this exercise is undertaken for England, treatment is estimated to have increased prevalence reduction by 0.27 percentage points out of a total of 0.75 in 2012, saving 750 lives per year Increasing quit attempt rates in India by brief advice could increase prevalence reduction by 0.7 percentage points in the first year reducing the annual deaths from smoking by 22,700 The model used needs to be developed and validated Conclusions 22