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Open Access Study protocol

Study protocol for a non-inferiority trial of cytisine versus nicotine replacement therapy in people motivated to stop smoking

Natalie Walker1*, Colin Howe1, Chris Bullen1, Hayden McRobbie2, Marewa Glover3, Varsha Parag1, Jonathan Williman1, Reon Veale4, Vili Nosa5 and Joanne Barnes6

Author Affiliations

1 Clinical Trials Research Unit, School of Population Health, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand

2 UK Centre for Tobacco Control Studies, Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, UK

3 Centre for Tobacco Control Research, Social and Community Health, School of Population Health, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand

4 The Quit Group, PO Box 12605, Wellington, New Zealand

5 Pacific Health, School of Population Health, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand

6 School of Pharmacy, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand

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BMC Public Health 2011, 11:880  doi:10.1186/1471-2458-11-880

Published: 21 November 2011

Abstract

Background

Smokers need effective support to maximise the chances of successful quit attempts. Current smoking cessation medications, such as nicotine replacement therapy (NRT), bupropion, nortriptyline or varenicline, have been shown to be effective in clinical trials but are underused by smokers attempting to quit due to adverse effects, contraindications, low acceptability and/or high cost. Cytisine is a low-cost, plant-based alkaloid that has been sold as a smoking cessation aid in Eastern Europe for 50 years. A systematic review of trial evidence suggests that cytisine has a positive impact on both short- and long-term abstinence rates compared to placebo. However, the quality of the evidence is poor and insufficient for licensing purposes in many Western countries. A large, well-conducted placebo-controlled trial (n = 740) of cytisine for smoking cessation has recently been published and confirms the findings of earlier studies, with 12-month continuous abstinence rates of 8.4% in the cytisine group compared to 2.4% in the placebo group (Relative risk = 3.4, 95% confidence intervals 1.7-7.1). No research has yet been undertaken to determine the effectiveness of cytisine relative to that of NRT.

Methods/design

A single-blind, randomised controlled, non-inferiority trial has been designed to determine whether cytisine is at least as effective as NRT in assisting smokers to remain abstinent for at least one month. Participants (n = 1,310) will be recruited through the national telephone-based Quitline service in New Zealand and randomised to receive a standard 25-day course of cytisine tablets (Tabex®) or usual care (eight weeks of NRT patch and/or gum or lozenge). Participants in both study arms will also receive a behavioural support programme comprising an average of three follow-up telephone calls delivered over an eight-week period by Quitline. The primary outcome is continuous abstinence from smoking at one month, defined as not smoking more than five cigarettes since quit date. Outcome data will also be collected at one week, two months and six months post-quit date.

Discussion

Cytisine appears to be effective compared with placebo, and given its (current) relative low cost may be an acceptable smoking cessation treatment for smokers, particularly those in low- and middle-income countries. Cytisine's 'natural' product status may also increase its acceptability and use among certain groups of smokers, such as indigenous people, smokers in countries where the use of natural medicines is widespread (e.g. China, India), and in those people who do not want to use NRT or anti-depressants to help them quit smoking. However it is important to ascertain the effectiveness of cytisine compared with that of existing cessation treatments.

Trial registration

Australian New Zealand Clinical Trials Registry (ACTRN12610000590066)