Abstract
INTRODUCTION: Oral smokeless tobacco (OST) is a major preventable risk factor for oral cancer. Nicotine replacement therapy (NRT), a commonly used pharmacological treatment in tobacco cessation interventions that help in reducing the withdrawal symptoms that individuals might experience in their attempt to quit. This systematic review aimed to assess NRT's effectiveness on OST cessation and reduction rates, addressing gaps in prior studies by incorporating recent research across diverse populations, including developing and developed countries. METHODS: A systematic search was conducted across PubMed, Cochrane, Embase, and Web of Science. The inclusion criteria were: English articles (2004 to June 2024), OST users of both genders, NRT intervention, control group (generic, placebo, or no intervention), and a 7-day point prevalence of OST abstinence and reduction at week 12. Studies were excluded if they lacked relevant outcomes, were non-English, or published before 2004. Data abstraction forms were used to extract study characteristics and results. The Practical Meta-Analysis Effect Size Calculator determined the effect sizes and directions. The risk of bias was assessed using Cochrane Collaboration's tool. RESULTS: Eleven studies were included with 40-1067 sample size. Seven were effective on OST abstinence, with effect sizes ranging from d=0.10 to d=0.54 and odds ratios from OR=1.67 to OR=4.10. One study demonstrated OST reduction (d=0.16 for dips/day and d=0.17 for cans/week). Nicotine dependence, NRT dosage, self-efficacy and social support were identified as key factors influencing the NRT's effectiveness in the included studies. CONCLUSIONS: NRT can aid in OST cessation. Combination of NRT with other interventions such as coach calls and web-based interactive setting can enhance the OST abstinence rate. The evidence, though promising, is limited by study variability, and inconsistent outcome reporting. Future studies should explore self-efficacy, social support, and NRT dosage with larger sample sizes for better assessment.