The volume of attention to our study in the U.S. and international press is not surprising, considering the widespread promotion of nicotine replacement products to all smokers in the population, and their growing inclusion in government subsidized health plans. Prior to addressing criticisms made by Stapleton and others, we note that their comments reflect at least one important area of agreement. The fact that no advantage for long term abstinence was found for users of nicotine replacement therapies (NRT) comes as no surprise even to critics of the study findings underscores general consensus that NRT treatment has not solved the problem of relapse to smoking.
The argument is that our study ignores initial quit rates and that improved initial quit rates would be expected to have a long-lasting effect on population smoking rates. The logic of this argument is that use of NRT will increase the number of smokers in the population who quit initially, and even given the same relapse rate as of non-users, NRT would result in a larger number of long term quitters than would be the case had none of the smokers used it initially. That hope or expectation was prominent around the time that the U.S. Food and Drug Administration permitted NRT to be sold without prescription. Unfortunately, however, the predicted increases in both rates of quitting and long-term quitters failed to materialize, (Pierce et al., 2012) even though annual sales of NRT in the U.S. increased dramatically.
The meta-analyses by Etter et. al., which Stapleton suggests provides better information than our recent study, is also based on clinical trials, and subject to limitations for assessing population effectiveness as discussed in our paper. Further, none of the prospective studies reviewed in Hughes et. al. found a population effect of over-the-counter NRT.
The argument has been made that a form of selection bias may have occurred in which persons more addicted may have been more likely to seek treatment and also have been more prone to relapse. The likelihood of such a bias affecting the results was diminished by the study's control for level of dependence. On the contrary, the counterargument could be made that persons who made the effort to try and use NRT were actually more highly motivated to quit and consequently should have been less likely to relapse, in further support of our study's findings. Indeed, because of the primary role of motivation in cessation, clinical trials for NRT tend to be highly selective for subjects who are strongly motivated to try and quit.
The possibility of recall bias (that people who quit a longer time ago would find it more difficult to recall whether or not they used NRT) was addressed in the study by a sensitivity analysis, the results of which showed consistency of findings based on prior six months, one year, and two years reported abstinence. The sample size was reasonable for this study; and, a point missed by Stapleton, was sufficient to detect a statistically significantly <higher> rate of relapse among formerly heavy smokers who used NRT without counseling.
Although a major objective of the study was not to assess adherence to NRT use or reasons for its inappropriate use, the fact that many NRT users did not continue to use it for the recommended eight weeks raises more of a question regarding its effectiveness outside of the controlled trial setting than doubt regarding the findings.
Braillon and Dubois suggested the results might have differed had we analyzed covariates using alternative forms. We analyzed the data using categorical as well as ordinal variables for dependence, including a three -category scale from the Fagerstrom Test of Nicotine Dependence, and four- category variables representing numbers of packs smoked per day, age as well as education, respectively. Analyzing these variables as categorical is common practice. We do not think that the continuous form is necessarily a better representation than the ordinal form for each of these variables since the theorized relationships with relapse are not necessarily linear and monotonic. The results of these analyses with respect to NRT were qualitatively the same as the original analyses showing no differences except that use of NRT for at least six weeks without counseling was associated with higher rates of relapse.
Finally, Beard et. al. reports regarding smokers who "had not smoked for the last 4 weeks" and no misrepresentation was intended.
We are gratified by the attention that our study has received because we think it is important to examine the evidence both for and against this approach to one of the most vexing public health scourges of our time - tobacco addiction.
Pierce JP, Cummins SE, White MM, Humphrey A, Messer K. Quitlines and Nicotine Replacement for Smoking Cessation: Do We Need to Change Policy? Annu Rev Public Health. 2012 Apr 4. [Epub ahead of print]
Etter JF, Stapleton JA. Nicotine replacement therapy for long- term smoking cessation: a meta-analysis. Tob Control 2006;15:280-5.
Hughes JR, Peters EN, Naud S. Effectiveness of over-the-counter nicotine replacement therapy: a qualitative review of nonrandomized trials. Nicotine Tob Res. 2011;13:512-22.
Beard, E., McNeill, A., Aveyard, P., Fidler, J., & West, R. Association between use of nicotine replacement therapy for harm reduction and smoking cessation: a prospective study of English smokers. Tobacco Control, 10.1136/tobaccocontrol-2011-050007 Online 1 December 2011.
Conflict of Interest: