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Tob Induc Dis. 2016 Feb 3;14:5. doi: 10.1186/s12971-016-0070-2. eCollection 2016.

Non-responders in a quitline evaluation are more likely to be smokers - a drop-out and long-term follow-up study of the Swedish National Tobacco Quitline.

Author information

1
Centre for Clinical Research, Uppsala University, Västmanland County Hospital, 721 89 Västerås, Sweden.
2
Centre for Clinical Research, Uppsala University, Västmanland County Hospital, 721 89 Västerås, Sweden ; Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
3
Department of Public Health Sciences, Social Medicine, Karolinska Institutet and Centre for Epidemiology and Community Medicine, Stockholm County Council, Stockholm, Sweden ; Reykjavik University, Reykjavik, Iceland.

Abstract

BACKGROUND:

A previous randomized controlled trial (RCT) of the Swedish National Tobacco Quitline detected no significant differences in smoking cessation outcomes between proactive and reactive services at 12-month follow-up. However, the response rate was only 59 % and non-responders were over-represented in the proactive service. We performed a drop-out analysis to assess the smoking status of initial responders and non-responders.

METHODS:

At 29-48 months after the first call, a postal questionnaire with six questions was sent to 150 random clients from the RCT database, with equal numbers from the proactive and reactive services as well as responders and non-responders at 12-month follow-up. Clients who did not return the questionnaire were contacted by telephone. The outcome measures were point prevalence (PP) and 6-month continuous abstinence (CA), and their associations with response status at 12 months were assessed by logistic regression.

RESULTS:

The response rate was 74 % (111/150). Abstinence was significantly higher among initial responders than non-responders (PP 54 % vs. 32 %, p = .023 and CA 49 % vs. 21 %, p = .003). The odds ratios for initial responders vs. initial non-responders were, for PP = 2.5 (95 % CI 1.1-5.6, p = .024), and for CA = 3.7 (95 % CI 1.5-8.9, p = .004), after adjusting for proactive/reactive service.

CONCLUSIONS:

Non-responders to a 12-month follow-up smoking cessation questionnaire in a quitline setting were more likely to be smokers 1.5-3 years later. We propose a conservative correction factor of 0.8 for self-reported abstinence in telephone-based cessation studies if the response rate is approximately 55-65 %.

KEYWORDS:

Effectiveness; Intention-to-treat; Non-response; Per protocol; Proactive; Questionnaire; Reactive; Responder-only analysis; Smoking; Telephone

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