Role of biochemical markers as adjuncts to the Fagerström test in evaluating nicotine dependence

Introduction: Nicotine dependence assessment is essential in smoking cessation programs. The Fagerström Test for Nicotine Dependence (FTND) is widely used, but its subjective nature limits accuracy. Biomarkers such as cotinine, exhaled carbon monoxide (CO), and carboxyhemoglobin (COHb) provide objective measures of tobacco exposure and dependence. Methods: A prospective observational study was conducted at the Smoking Cessation Unit of Salamanca University Hospital from 2009 to 2022. A total of 3820 smokers were included. Demographic data, smoking history, and dependence level were recorded. Biomarkers, including serum cotinine, exhaled CO and COHb, were measured. The correlation between biomarkers and FTND scores was analyzed. Results: Cotinine levels showed the strongest correlation with FTND scores (r = 0.302, p < 0.001), followed by COHb (r = 0.234, p < 0.001) and exhaled CO (r = 0.219, p < 0.001). Conclusion: Biomarkers offer a reliable alternative to subjective nicotine dependence assessments. Cotinine proved to be the most accurate marker. Integrating biomarkers into clinical practice could improve cessation outcomes by enabling personalized treatment strategies.