Arthur Jeske DMD, PhD; James Zahrowski DMD, MS, PharmD
Evidence from seven randomized controlled trials concluded that nicotine replacement therapy (NRT), compared to placebo, can double the sustained smoking abstinence rate in smokers who have no intention to quit.
In adult smokers who have no intention of quitting, does nicotine replacement therapy (NRT) effectively and safely increase six-month smoking cessation rate?
The authors included both published and unpublished randomized, placebo-controlled trials that enrolled smokers who had no intention of quitting; the trials compared NRT with placebo (with or without motivational support) and reported quit rates. Two independent reviewers assessed the eligibility of the studies. One reviewer assessed study quality and extracted data while another checked process accuracy. The primary outcome, six months of sustained smoking abstinence, was assessed by data analysis. Secondary outcomes were defined as point abstinences, sustained reduction, and defined point reduction. Adverse effects were death, hospital admission, disability, discontinuation of NRT, and nausea. Individual patient data analyses and the development of a floating 6 month abstinence outcome measure were key to produce meaningful findings. (1-3)
The authors selected seven controlled randomized trials (2,767 smokers) that evaluated the following types of nicotine replacement therapies: nicotine gum (4 studies), nicotine inhaler (2 studies), and free choice (1 study). In each study, participants used NRT for six-to-18 months. The duration of the studies varied between 12 and 26 months. The NRT group attained 6.75 percent sustained smoking abstinence for six months, twice the rate of those receiving placebo (relative risk [RR] = 2.06l; 95 percent confidence interval [CI] 1.34-3.15). The number needed to treat (NNT) was 29. All other cessation and reduction outcomes were significantly more likely in smokers who received NRT instead of placebo. No statistically significant differences in adverse events were reported (death, odds ratio [OR] 1.00, 95 percent CI 0.25-4.02; serious adverse events 1.16, 0.79-1.50) and discontinuation 1.25, 0.64-2.51). Nausea was more common with NRT (8.7 percent vs. 5.3 percent; OR 1.69, 95 percent CI 1.21-2.36).
Nicotine replacement therapy is an effective intervention for smokers who have no intention of quitting smoking to achieve abstinence. However, the trials whose evidence supported this finding were studies in which participants also received regular behavioral support and monitoring. Thus, this review fails to makes clear which is more effective, NRT used as a sole modality or NRT supplemented with additional support and monitoring.
Source of Funding:
UK Health Technology Assessment Programme (National Institute for Health Research)UK Health Technology Assessment Programme (National Institute for Health Research)
Importance and Context:
Smoking is one of the most preventable causes of illness and premature death. Currently, 45 million people in the U.S. smoke tobacco and 435,000 people die annually from smoking related diseases. (4) Despite 70 percent of smokers intending to stop at some time, only 12 percent are ready to stop smoking. Many smokers try to stop every year, but only 2 to 3 percent succeed. A six-month smoking cessation is important to evaluate because half of the smokers who achieve abstinence for 6 months sustain their abstinence for a lifetime. Nicotine replacement therapy is the most widely used smoking cessation aid. As a nicotine delivery system (gum, lozenges, sublingual tablets, inhaler, or dermal patches), NRT administers a lower level of nicotine than cigarettes. This reduces nicotine withdrawal symptoms, which leads to increased motivation to quit. Thus, a systematic evaluation of evidence relating to NRT is needed, regarding the outcome of sustained smoking cessation in the majority of the smoking population, which has no intention to quit.
Strengths and Weaknesses of the Systematic Review:
The authors conducted a comprehensive search of six electronic data bases from 1992 to November 2007 and used accepted methods to screen articles for inclusion. Primary outcome and secondary outcomes were defined. The authors summarized smoking data using relative risk (RR). They summarized adverse effects data using Peto odds ratio. They performed homogeneity test of the included studies.
Strengths and Weaknesses of the Evidence:
The authors selected seven high-quality randomized controlled trials, six of which were sponsored by NRT pharmaceutical companies. In most of the studies, the primary outcome in these trials was smoking reduction and not a completed six-month cessation. Study participants were heavy smokers, typically recruited by advertisement. The authors did not separate NRT from beneficial behavioral support.
Implications for Dental Practice:
This systematic review shows that in a population of smokers not ready to stop, NRT results in a 6 percent six-month cessation rate as compared to 3 percent rate for placebo. Nicotine replacement therapy also helped a significant number of participants, who otherwise would not have stopped smoking. Overall, NRT effect exerted a modest effect in smokers, with only one smoker out of a total of 29 expected to achieve sustained smoking abstinence. All forms of NRT were well tolerated without adverse effects except for slightly more nausea, likely due to a higher nicotine level in participants who continued to smoke while receiving NRT. Nicotine replacement therapy has shown a 50-70 percent increase in long-term smoking cessation in motivated, high nicotine dependent patients who did not receive behavioral support.(5)
1. Moore D, Aveyard P, Connock M, Wang D, Fry-Smith A, Barton P. Effectiveness and safety of nicotine replacement therapy assisted reduction to stop smoking: systematic review and meta-analysis. BMJ 2009;338:b1024
2. Aveyard P, Wang D, Connock M, Fry-Smith A, Barton P, Moore D. Assessing the outcomes of prolonged cessation-induction and aid-to-cessation trials: Floating prolonged abstinence. Nicotine & Tobacco Research 2009; doi: 10.1093/ntr/ntp035
3. Wang D, Connock M, Barton P, Fry-Smith A, Aveyard P, Moore D. 'Cut down to quit' with nicotine replacement therapies in smoking cessation: a systematic review of effectiveness and economic analysis. Health Technology Assessment 2008;12
4. Benowitz NL. Nicotine addiction. N Engl J Med. 2010; 362:2295-2303.
5. Stead LF, Perera R, Bullen C, Mant D, Lancaster T. Nicotine replacement therapy for smoking cessation. Cochrane Database of Systematic Reviews 2008, Issue 1. Art. No.: CD000146. DOI: 10.1002/14651858.CD000146.pub3.