Comparison with literature
The available evidence on effectiveness of delivering LA or exhaled CO feedback on smoking cessation is summarised in a Cochrane review published in 2019 [The Cochrane review also included two studies testing LA. The first study was small (VBA is recommended as standard care in primary care in LMIC settings by the World Health Organisation [There are a number of factors that may have contributed to the low absolute quit rates seen within our study. In terms of fidelity to intervention delivery, quantitative measures taken across all trial participants indicated that this was high for the LA, CO and VBA protocols, however recordings of a sample of baseline consultations indicated that fidelity to the VBA protocol was reduced for the lung age and CO arms compared to the VBA arm alone. It is possible that delivery of the LA and CO components distracted GPs from delivering the full VBA protocol, and this may have masked differences in effectiveness between these approaches. In line with the protocol, participants setting a quit date did so within a week of the baseline visit. However, uptake of behavioural support was low with participants receiving an average of two out of a possible five sessions offered as part of the standard programme for behavioural support, and only 34% indicated that they had used some form of pharmacotherapy.In addition to these reasons, generally speaking, smoking remains a strong part of the culture within North Macedonia. National smoking prevalence is high [The low numbers of quitters in our study may mean that our trial was underpowered, and small effects of brief interventions in primary care cannot be ruled out. However, the findings highlight the difficulty of influencing smokers through primary care services within North Macedonia alone. Tackling high national smoking prevalence will also be reliant on more complete adoption of the WHO FCTC population based tobacco control measures, and on making known effective pharmacotherapies more accessible and affordable. More research is needed to find effective ways to prompt and support quitting in primary care in North Macedonia.