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Impact of Canadian tobacco packaging policy on use of a toll-free quit-smoking line: an interrupted time-series analysis.

BACKGROUND
A policy for new pictorial health warning labels on tobacco packaging was introduced by Health Canada in 2012. The labels included, for the first time, a prominently displayed toll-free number for a quit-smoking line. We used data from the Ontario provincial quitline to investigate the call volume and number of new callers receiving treatment in the months before and after the new policy was introduced.


METHODS
We used an interrupted time-series analysis to examine trends in the overall call volume and number of new callers receiving treatment (≥ 1 telephone counselling session) through Ontario's quitline (Smokers' Helpline) between January 2010 and December 2013. We analyzed data using Box-Jenkins autoregressive integrated moving-average models; we adjusted the models for a major campaign promoting the quitline, a seasonality (January) effect and tobacco pricing.


RESULTS
We found a relative increase of 160% in the average monthly call volume during the 7 months after the introduction of the new labels (870 calls per month at baseline and 1391 additional calls per month on average after the policy change; standard error [SE] 108.94, p < 0.001), and a sustained increase of 43% in subsequent months. We observed a relative increase of 174% in the number of new callers receiving treatment (153 new callers per month at baseline and 267 additional new callers per month after the policy change; SE 40.03, p < 0.001) and a sustained increase of 80% in subsequent months. The effect was significant even after controlling for a major promotion campaign and the January effect.


INTERPRETATION
We found a significant increase in the monthly overall call volume and number of new callers receiving treatment per month after the introduction of the new tobacco health warning labels, with a sustained increase in overall calls and new callers beyond the first 7 months. Our findings add to the body of evidence on the benefit of including a toll-free quitline number on tobacco packaging.