Randomised controlled trial testing effectiveness of feedback about lung age or exhaled CO combined with very brief advice for smoking cessation compared to very brief advice alone in North Macedonia:

This multicenter, randomized trial examined the effectiveness and cost-effectiveness of lung age or exhaled carbon monoxide feedback combined with very brief advice to prompt smoking cessation, as compared with very brief advice alone, in 1368 smokers in North Macedonia. Information regarding lung age was collected using the Vitalograph COPD-6 device.