Rare outcomes, self-harm and suicide, were used in previous analyses; the investigators will have greater power to explore more common outcome measures within this project. For example, in the previous analysis the nine month age- and sex-adjusted hazard ratio for all-cause mortality nine months after first prescription for varenicline vs. nicotine replacement therapy was 0.43 (95% CI: 0.35 to 0.53); after controlling for possible confounders this became: 0.49 (95% CI: 0.40 to 0.61). A 70% increase in sample size would lead to a reduction of the standard error by a factor of 1.3, reducing the breadth of the above-adjusted confidence interval from 0.21 to 0.16.