Table 2.
Comparison of three methods for estimating smoking-attributable fraction and mortality
| Multivariable predictive algorithm | Levin's Method | Population-attributable fraction | |
|---|---|---|---|
| Method comparison | |||
| Overview | Multivariable models relating exposure (and covariates) to outcome are created, then applied to current exposure data in the target population to predict total burden. The models may be created from earlier years of data from the same target population. | Rate of outcome in the total population is compared to the rate in the unexposed population to estimate the contribution of exposure to excess outcome. | Prevalence of exposure in the target population is combined with hazards relating exposure to outcome from an etiologic study. This is done to estimate proportion of burden attributable to the exposure in the population. |
| Computational method | The models are applied to a counterfactual population where no one is exposed | (AFp) = (It-Iu)/It, AFp is multiplied by total outcome count (see text) | AFp = [Pe(RR-1)]/[1 + Pe(RR-1)], AFp multiplied by total outcome count (see text) |
| Typical data Source | Population-based, routinely collected data on health outcomes that are linked at the individual level to exposure data, often from health surveys. | Not commonly available at the population level. Cohort studies, disease registries, or exposure data linked to outcome. | Ecological, summary measures of: prevalence from health surveys, hazards from the literature, and outcome counts from routinely collected data. |
| Study data sources | |||
| Smoking prevalence (target population) | Canadian Community Health Survey (CCHS) 4.1 | Not used | CCHS 4.1 |
| Hazard estimates | CCHS 1.1 to 3.1 linked to death database | Not used | Cancer Prevention Study II, 2014 Surgeon General’s Report [8] |
| Mortality estimates | Predicted by algorithm | CCHS 1.1 to 3.1 linked to death database | Death database (RPDB) |
| Smoking-attributable fraction/deaths, 2009–2010 | |||
| Males | |||
| Smoking-attributable fraction (AF p ) | 26.1% | 36.8% | 24.1% |
| Smoking-attributable mortality (SAM) | 11 332 | 15 998 | 10 648 |
| Females | |||
| AF p | 21.4% | 33.9% | 15.8% |
| SAM | 9 285 | 14 713 | 6 928 |
| Total | |||
| AF p | 23.7% | 35.4% | 20.0% |
| SAM | 20 573 | 30 711 | 17 576 |