Estimating the number of quit attempts it takes to quit smoking successfully in a longitudinal cohort of smokers

Abstract

Objectives: The number of quit attempts it takes a smoker to quit successfully is a commonly reported figure among smoking cessation programmes, but previous estimates have been based on lifetime recall in cross-sectional samples of successful quitters only. The purpose of this study is to improve the estimate of number of quit attempts prior to quitting successfully.

Design: We used data from 1277 participants who had made an attempt to quit smoking in the Ontario Tobacco Survey, a longitudinal survey of smokers followed every 6 months for up to 3 years beginning in 2005. We calculated the number of quit attempts prior to quitting successfully under four different sets of assumptions. Our expected best set of assumptions incorporated a life table approach accounting for the declining success rates for subsequent observed quit attempts in the cohort.

Results: The estimated average number of quit attempts expected before quitting successfully ranged from 6.1 under the assumptions consistent with prior research, 19.6 using a constant rate approach, 29.6 using the method with the expected lowest bias, to 142 using an approach including previous recall history.

Conclusions: Previous estimates of number of quit attempts required to quit may be underestimating the average number of attempts as these estimates excluded smokers who have greater difficulty quitting and relied on lifetime recall of number of attempts. Understanding that for many smokers it may take 30 or more quit attempts before being successful may assist with clinical expectations.

Keywords: addiction; longitudinal; population; smoking cessation.

Figure 1

Estimated probability of successful quitting (quit attempt of longer than 1 year) by quit attempt number in the Ontario Tobacco Survey. The top figure includes only observed quit attempts, while the bottom figure also includes reported quit attempts prior to study entry. Dotted lines represent upper and lower CIs. A life table analysis was used to calculate probabilities (n=1277).

Figure 2

Absolute survival probability (per cent who have not quit successfully) of reported quit attempts of longer than 1 year during the first 18 months of observation in the Ontario Tobacco Survey. The top figure includes only observed quit attempts, while the bottom figure also includes reported quit attempts prior to study entry. Dotted lines represent upper and lower CIs. A life table analysis was used to calculate survival probabilities (n=1277).