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Drug Alcohol Depend. 2018 Sep 1;190:72-81. doi: 10.1016/j.drugalcdep.2018.04.035. Epub 2018 Jun 26.

Predicting smoking abstinence with biological and self-report measures of adherence to varenicline: Impact on pharmacogenetic trial outcomes.

Author information

1
Department of Pharmacology and Toxicology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada. Electronic address: a.peng@mail.utoronto.ca.
2
Department of Psychiatry and Abramson Cancer Center, University of Pennsylvania, 3535 Market Street, 4th Floor, Philadelphia, PA, 19104, United States. Electronic address: schnoll@mail.med.upenn.edu.
3
Department of Psychology, State University of New York at Buffalo, 230 Park Hall, The State University of New York, Buffalo, NY, 14260-4110, United States. Electronic address: lhawk@buffalo.edu.
4
Department of Behavioral Science, The University of Texas MD Anderson Cancer Center, 1155 Pressler St, Houston, TX, 77030, United States. Electronic address: pcinciri@mdanderson.org.
5
Addictions Division, Centre for Addiction and Mental Health and Division of Brain and Therapeutics, Department of Psychiatry, University of Toronto, 100 Stokes Street BGB 3288, Toronto, ON, M6J 1H4, Canada. Electronic address: tony.george@camh.ca.
6
Department of Psychiatry and Abramson Cancer Center, University of Pennsylvania, 3535 Market Street, 4th Floor, Philadelphia, PA, 19104, United States. Electronic address: clerman@upenn.edu.
7
Department of Pharmacology and Toxicology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada; Addictions Division, Centre for Addiction and Mental Health and Division of Brain and Therapeutics, Department of Psychiatry, University of Toronto, 100 Stokes Street BGB 3288, Toronto, ON, M6J 1H4, Canada. Electronic address: r.tyndale@utoronto.ca.

Abstract

INTRODUCTION:

Adherence to pharmacotherapies for tobacco dependence, such as varenicline, is necessary for effective treatment. The relationship between varenicline adherence, determined by commonly used indirect (i.e., self-reported pill counts) and infrequently used direct (i.e., varenicline levels) methods, and abstinence outcomes have not been previously examined, nor has their impact on the outcomes of a genetically randomized clinical trial been assessed.

METHODS:

At Week 1 following target quit date, self-reported pill count and salivary varenicline levels were obtained from participants (N = 376) in a smoking cessation clinical trial (NCT01314001). Point-prevalence abstinence was biochemically-verified by salivary cotinine at Week 1 and by exhaled carbon monoxide at Week 1, end-of-treatment, 6 and 12 months following treatment. Blood nicotine metabolite ratio (NMR) was obtained at baseline.

RESULTS:

Adherent individuals based on varenicline levels were significantly more likely to be abstinent than non-adherent individuals at Week 1 (odds ratios [ORs] 1.92-3.16, p's≤0.006), end-of-treatment (OR = 2.53, p = .004), and six months following treatment (OR = 2.30, p = .03). In contrast, pill counts did not consistently predict abstinence. Including direct measures of adherence enhanced the association between rate of nicotine metabolism (NMR) and end-of-treatment abstinence; normal metabolizers (NMR ≥ 0.31) were significantly more likely than slow metabolizers (NMR < 0.31) to be abstinent at end-of-treatment (OR = 2.00, p = .005).

CONCLUSION:

Adherence based on salivary varenicline, rather than on pill counts, is predictive of Week 1 abstinence, irrespective of the biomarker of abstinence assessed, and of long-term abstinence. Direct measures of adherence enhance the ability to assess the impact of a biomarker or genetic marker on abstinence outcomes.

KEYWORDS:

Compliance; Smoking cessation; Treatment adherence; Treatment outcome; Varenicline

PMID:
29986268
PMCID:
PMC6085881
[Available on 2019-09-01]
DOI:
10.1016/j.drugalcdep.2018.04.035
[Indexed for MEDLINE]

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