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Two packs contain $40$ cigarettes. Holding height fixed, increasing average consumption from zero to two packs per day changes the log odds byThe corresponding odds ratio is thereforeThus the model estimates that a two-pack-per-day smoker has about $2.52$ times the odds of heart disease of an otherwise comparable nonsmoker. This is an association in the fitted observational model, rather than by itself a causal conclusion.

Because the second model is saturated, its fitted worsening probabilities are the observed proportions:Thus the drug efficacy as a risk reduction isandThese are reasonably similar to the published estimates of $90.0\%$ and $62.1\%$.

The interaction coefficients provide the same quick comparison on the odds scale:They are treatment-versus-control odds ratio. Since worsening is rare in every group, each odds ratio is close to its risk ratio, giving the approximate efficacies $87.5\%$ and $65.3\%$.

The overall odds ratio is $0.99$ with 95% interval $(0.95,1.02)$, so there is little evidence for an average effect. The estimate changes sharply across residual-vitamin-D strata: it is $0.69$ $(0.59,0.80)$ in the deficient group, $0.94$ $(0.89,0.99)$ in the insufficient group, and close to one in the two higher groups. The pattern is consistent with effect modification: raising vitamin D may reduce mortality among deficient people but offer little benefit once concentration is adequate. The claim still depends on the Mendelian randomization assumptions and should account for the fact that several subgroup estimates were examined.