| Methods |
Design: three group parallel trial
Purpose: test the effect of nicotine replacement therapy, and placebo, in reducing cigarette consumption in smokers willing to intend to reduce number of smoked cigarettes but not to quit |
| Participants |
Patients: cigarette smokers unwilling to quit, but intending to reduce smoking by half
Baseline comparability: not for gender (54% male in nicotine group and 44% in no treatment group); yes for age, cigarette consumption, intention to reduce consumption (and several other variables) |
| Interventions |
Placebo: transdermal patch, gum, or inhaler without nicotine (and information leaflet) mailed every other week at the choice of the patient for 6 months
Untreated: no transdermal patch, gum, inhaler or leaflet
Experimental: transdermal patch, gum, inhaler with nicotine (and information leaflet)
(Co‐intervention: information booklet after three months) |
| Outcomes |
Mean number of cigarettes smoked per day after 6 months
Score of smoking intensity (0 to 100)
Score of total smoke inhalation per day (0 to 10)
Mean number of reduction of smoked cigarettes per day
Smoking cessation rate |
| Notes |
Not 1:1 randomisation. The combination of baseline inequality for gender, and lack of clear description of concealment of allocation indicate possible selection bias. In the no treatment group 7% did not provide information on smoking habits; in the placebo group it was 3%. For these individuals the baseline values were computed as the end result. Because the dropout rate was higher in the no‐treatment group this may have resulted in an inflated estimate of the mean number of smoked cigarettes, and thus a too optimistic estimate of the effect of placebo on smoking reduction. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Adequate sequence generation? |
Low risk |
‘computer generated list of random numbers' |
| Allocation concealment? |
Unclear risk |
NS |
| Blinding?
Treatment provider |
High risk |
Not described as double‐blind (placebo/drug) |
| Blinding?
Outcome assessor |
Unclear risk |
Not relevant as patient reported outcome |
| Incomplete outcome data addressed?
All outcomes |
Low risk |
Drop‐out < 15% |
| Free of selective reporting? |
Unclear risk |
No protocol available |
| Free of other bias? |
High risk |
See notes |
| No signs of variance inequality or skewness? |
Low risk |
No variance inequality (F‐test not statistically significant) and no skewness (1.64 standard deviations does not exceed the mean) |
| Trial size > 49? |
Low risk |
N = 658 |
| Clearly concealed allocation + trial size > 49 + drop‐out max 15% |
High risk |
Allocation not clearly concealed |
