Is the nicotine metabolite ratio a useful tool to improve the effectiveness, safety and adherence to quitting smoking? Systematic review of the literature and meta-analysis

We have carried out a systematic review of the literature (SRL) and a meta-analysis (MA) to answer: 1. Validity of the nicotine metabolite ratio (NMR) in improving the effectiveness of pharmacological treatments (PT) for smoking cessation (SC). 2. Validity of the NMR to improve the safety of the use of these PT? and 3. Validity of NMR in improving adherence to these PT?