4.2 Lung Health Study
The Lung Health Study was a clinical trial that assessed the benefits of smoking cessation over a time horizon of 5 years .
The model was built originally with active treatment arms and a placebo arm only. When this validation was conducted using the Lung Health Study, it was observed that the modelled annual mean rate of FEV1 decline was overestimated. This was attributed to an initial FEV1 boost in the placebo arm based on clinical trial data [, which cause patients discontinuing from placebo to have a significant drop in their FEV1 in line with the assumption described in Sect. of loss of treatment benefit upon treatment termination. In order to address this paradigm, a no treatment arm was added where it was assumed no initial benefit in FEV1 would be observed and patients would only be subject to a constant rate of FEV1 decline.
The model was re-run and it was observed that the mean rates of decline obtained after running the model were aligned with mean rates of decline published by Scanlon et al. , which highlights that the inclusion of a no treatment arm is appropriate and it is correctly used in the model (61.54 ml/year in smokers and 31.22 ml/year in ex-smokers obtained from the model vs. 62 ml/year in smokers and 31 ml/year in ex-smokers from the study publication ). These rates are used in the base case of the model and are not affected when no treatment is selected.