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Rapid Responses: Rapid Responses published:
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An Effective Intervention?
- Michael Siegel (5 April 2009)
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NNT 29
- Maneesh Gupta (11 April 2009)
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Re: NNT 29
- L Sam Lewis (14 April 2009)
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Responses to correspondents
- Paul Aveyard, David Moore, Martin Connock, Dechao Wang, Anne Fry-Smith, Pelham Barton (29 April 2009)
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The effect of the "chance of a good outcome"
- Florian Vogt, Theresa M Marteau (13 June 2009)
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Michael Siegel, Professor Boston University School of Public Health, Boston, MA, USA, 02118
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It appears to me that the conclusions of this paper are highly slanted. With a long-term smoking cessation percentage of only 1.6%, one can hardly call NRT treatment an "effective" intervention in this situation. Even though the 1.6% abstinence rate is better than the 0.4% achieved with placebo, how can one call the 1.6% success rate with NRT to be "effective?" In fact, the logical conclusion from this paper is that NRT was a dismal intervention. The overwhelming majority of smokers - 98.4% - failed to achieve long-term sustained abstinence with NRT treatment. Given the presence of a financial conflict of interest with a pharmaceutical company that manufactures nicotine replacement products, it certainly has the appearance that this conflict has biased the interpretation of the findings and the study conclusion. I can't quite think of another intervention for which a 98.4% failure rate would be considered a success. Competing interests: None declared |
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Maneesh Gupta, Consultant Psychiatrist Community Substance Misuse Team, West Sussex, PO21 1ER
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I am surprised at the results of this review and metanalysis. If only 6.75% of patients had sustained abstinence at six months, then the question to ask is, whether nicotine replacement therapy (NRT) is cost effective or not. The number needed to treat is 29 which is very high and any health intervention which is licenced as an evidence based tool, needs to do much more. In clinical practice, we would now have to advise our clients that NRT will help in cutting down but whether NRT is effective at sustained abstinence is debatable. Competing interests: None declared |
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L Sam Lewis, GP Trainer Surgery, Newport, Pembrokeshire, SA42 0TJ
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I beg to differ with Maneesh Gupta.. An NNT of 29 compares very well with most other approved and common medical interventions. For example, treatment of mild to moderate hypertension carries an NNT of 800 man-years to prevent one stroke, whilst in high-risk post-MI patients a statin offers an NNT of about 25 ( 4S study ) for each year of Statin swallowed. The Nicotine Replacement one-off stratagem requires no more than a month or two of Nicotine (I advise just a week or two), and is therefore very quick and cheap (compared to no action, or other CVD risk interventions such as Statin or BP treatment). Cold Turkey and gumption are also quick and valuable, but not so easily costed. " Giving up smoking is easy - I have done it many times ! " ( apologies to Mark Twain ) Dr Sam Lewis , ex-smoker at the moment. Competing interests: None declared |
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Paul Aveyard, Senior Lecturer University of Birmingham B15 2TT, David Moore, Martin Connock, Dechao Wang, Anne Fry-Smith, Pelham Barton
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Siegel is surprised that we concluded that the intervention was effective and cannot think of other interventions that would be regarded as effective with such a high failure rate. He chooses a secondary outcome from our review to make his point, but as it excludes 76% of all the people that stopped smoking for a long time, this is not an accurate measure of the impact of the programme. Overall, offering up to one year of treatment with NRT helped 6.75%-3.28%=3.47% or one in 29 users sustain long-term abstinence. About half will become lifetime abstainers1;2, and about half of those will be prevented from premature death3, which gives an NNT for prevention of premature death of about 120. This NNT compares favourably with other preventative interventions, as Lewis points out. Five years of treatment with statins in those at risk of cardiovascular disease gives an NNT of 931 for preventing one death, while one year of treatment for hypertension in middle aged people gives an NNT of 850 for stroke prevention4. Such treatments are widely accepted as effective, but the absolute benefits are small or the treatment is a failure for nearly everyone who takes it. In assessing the benefits of treatment, it is helpful to remember that smoking is largely sustained by tobacco addiction and that reinstatement after abstinence is characteristic of an addiction. This creates the high relapse rates and thus treatment for unwilling quitters could be compared with treatment for willing quitters or treatment for other addictions. Smokers trying to stop using NRT to assist them without support results in about 8% quitting5, and with modest behavioural support as provided by practice nurses gives similar results6. More intensive support and medication results in about 15% quitting in the long term7. These treatment effect sizes are not very different from the 7% or so observed in unwilling quitters and treatment effects are not small judged in this context. Gupta raises the issue of cost-effectiveness. As can be seen above, high failure rates are characteristic of treatments for addiction, but NICE have called smoking cessation treatments as ‘among the most cost- effective of all healthcare interventions’ (p78). We have published a cost-effectiveness analysis elsewhere and patients in these programmes used surprisingly little NRT on average- typically about 2 pieces of gum per day- so that the overall cost for the year long programme was about £100 on average for the NRT and about £50 for behavioural support and ancillary costs9. Both are similar to the estimates for treatment costs for short-term treatment in willing quitters. Consequently, the cost- effectiveness of treatment in this group is only slightly worse than for smoking cessation treatment in willing quitters, with a cost per QALY of less than £5000. This is well below the threshold at which NICE regards treatment as affordable. Neither NICE nor the US guidelines recommended smoking reduction programmes, though the New Zealand guidance did10-12. This is due to concerns that allowing smoking reduction would give the wrong message to the public not doubts about effectiveness or cost-effectiveness. These doubts will only be fully resolved by public health trials measuring total effects in populations, which are important, given the strong evidence of effectiveness and cost-effectiveness. Surveys suggest that most smokers might use these treatments and thus the potential public health benefit from these programmes is great. Reference List (1) Stapleton J. Cigarette smoking prevalence, cessation and relapse. Statistical Methods in Medical Research 1998; 7(2):187-203. (2) Etter JF, Stapleton JA. Nicotine replacement therapy for long- term smoking cessation: a meta-analysis. Tobacco Control 2006; 15(4):280- 285. (3) Doll R, Peto R, Boreham J, Sutherland I. Mortality in relation to smoking: 50 years' observations on male British doctors. BMJ 2004; 328(7455):1519. (4) Longmore M, Wilkinson IB, Rajagapolan S. Oxford handbook of clinical medicine. 6 ed. Oxford: Oxford University Press; 2004. (5) Hughes JR, Shiffman S, Callas P, Zhang J. A meta-analysis of the efficacy of over-the-counter nicotine replacement. Tob Control 2003;(1):21 -27. (6) Aveyard P, Brown K, Saunders C, Alexander A, Johnstone E, Munafo MR et al. A randomised controlled trial of weekly versus basic smoking cessation support in primary care. Thorax 2007; In press. (7) Ferguson J, Bauld L, Chesterman J, Judge K. The English smoking treatment services: one-year outcomes. Addiction 2005; 100(s2):59-69. (8) National Institute for Health and Clinical Excellence. Guidance on the use of nicotine replacement therapy (NRT) and bupropion for smoking cessation. http://www nice org uk/nicemedia/pdf/NiceNRT39GUIDANCE pdf [ 2002 [cited 2008 Feb. 16];[1-27] (9) Wang D, Connock M, Barton.P., Fry-Smith A, Aveyard P, Moore D. Cut Down to Quit with Nicotine Replacement Therapies (NRT) in Smoking Cessation: Systematic review of effectiveness and economic analysis. Health Technol Assess 2008; 12(2). (10) Fiore MC, Jaen CR, Baker TB, Bailey WC, Benowitz NL, Curry SJ et al. Treating tobacco use and dependence: 2008 update. U S Department of Health and Human Services 2008;1-256. (11) National Institute for Health and Clinical Excellence. Guidance on smoking cessation. 2008. Ref Type: Report (12) Ministry of Health. Smoking cessation guidelines. 1-54. 2007. Wellington, New Zealand, Ministry of Health. Ref Type: Report Competing interests: Paul Aveyard has done consultancy work on behalf of manufacturers of pharmacotherapy for smoking cessation |
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Florian Vogt, Cancer Research UK Research Fellow King's College London, SE1 9RT, Theresa M Marteau
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Siegel asks why, given 98% of people continue to smoke after using NRT (1), Moore, Aveyard and colleagues judge NRT to be effective (2). Aveyard, Moore and colleagues respond to Siegel by comparing the effectiveness of NRT to that of other lifesaving interventions using the “number needed to treat” (3), an effective technique for communicating the effectiveness of smoking cessation services to health professionals (4). This response, however, does not go to the heart of Siegel’s criticism which stems from a failure to separate the effect of a treatment from the effect of the natural history of the condition or behaviour resulting in the treatment effectiveness being judged on the overall “chance of a good outcome”. For example, individuals at risk of cardiovascular disease who take statins for 5 years have a 98% chance of not dying (NNT=107) (5). However, about 97% of comparable individuals who do not take statins will also not die. In summary, most individuals suffering from the ‘condition’ will have a good outcome whether they receive treatment or not. The reverse is true for smokers trying to quit: whether they receive treatment or not the vast majority will not succeed in quitting. While the impact of most smoking cessation interventions compare favourably to statins to prevent heart disease in terms of absolute risk reduction, the “chance of a good outcome” for the two patient groups could hardly be more different. Experimental research to document the effect of the “chance of a good outcome” on the perceived effectiveness of medical interventions is currently under way. 1. Siegel M. Nicotine replacement, effective? BMJ 2009;338:b1730. 2. 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. 3. Aveyard P, Moore D, Connock M, Wang D, Fry-Smith A, Barton P. Authors respond to criticism that treatment is ineffective. BMJ 2009;338:b1979. 4. Vogt F, Hall S, Hankins M, Marteau TM. Evaluating three theory- based interventions to increase physicians’ recommendations of smoking cessation services. Health Psychol. 2009;28(2):174-82. 5. Hebert P, Gaziano J, Chan K, Hennekens C. Cholesterol lowering with statin drugs, risk of stroke, and total mortality. Journal of the American Medical Association JAMA 1997;278:313-21. Competing interests: None declared |
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