Are non-responders in a quitline evaluation more likely to be smokers?
BACKGROUND
In evaluation of smoking cessation programs including surveys and clinical trials the tradition has been to treat non-responders as smokers. The aim of this paper is to assess smoking behaviour of non-responders in an evaluation of the Swedish national tobacco cessation quitline a nation-wide, free of charge service.


METHODS
A telephone interview survey with a sample of people not participating in the original follow-up. The study population comprised callers to the Swedish quitline who had consented to participate in a 12 month follow-up but had failed to respond. A sample of 84 (18% of all non-responders) was included. The main outcome measures were self-reported smoking behaviour at the time of the interview and at the time of the routine follow-up. Also, reasons for not responding to the original follow-up questionnaire were assessed. For statistical comparison between groups we used Fischer's exact test, odds ratios (OR) and 95% confidence intervals (CI) on proportions and OR.


RESULTS
Thirty-nine percent reported to have been smoke-free at the time they received the original questionnaire compared with 31% of responders in the original study population. The two most common reasons stated for not having returned the original questionnaire was claiming that they had returned it (35%) and that they had not received the questionnaire (20%). Non-responders were somewhat younger and were to a higher degree smoke-free when they first called the quitline.


CONCLUSIONS
Treating non-responders as smokers in smoking cessation research may underestimate the true effect of cessation treatment.
Tomson
Tanja
T
Stockholm Center for Public Health, Tobacco Prevention, Box 175 33, 118 91 Stockholm, Sweden. tanja.tomson@sll.se
Björnström
Catrine
C
Gilljam
Hans
H
Helgason
Asgeir
A
D000328:Adult; D015982:Bias; D005260:Female; D005500:Follow-Up Studies; D015438:Health Behavior; D015277:Hotlines; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D009313:National Health Programs; D010352:Patient Dropouts / Q000145:classification* / Q000706:statistics & numerical data; D015397:Program Evaluation / Q000379:methods* / Q000706:statistics & numerical data; D012907:Smoking / Q000453:epidemiology; D016540:Smoking Cessation / Q000379:methods / Q000706:statistics & numerical data*; D000074606:Smoking Prevention; D011795:Surveys and Questionnaires / Q000706:statistics & numerical data*; D013548:Sweden / Q000453:epidemiology; D017211:Treatment Failure