Background:

Most smoking cessation guidelines advise quitting abruptly. However, many quit attempts involve gradual cessation. If gradual cessation is as successful, smokers can be advised to quit either way.

Objective:

To examine the success of quitting smoking by gradual compared with abrupt quitting.

Design:

Randomized, controlled noninferiority trial. (International Standardized Randomized Controlled Trial Number Register: ISRCTN22526020).

Setting:

Primary care clinics in England.

Participants:

697 adult smokers with tobacco addiction.

Intervention:

Participants quit smoking abruptly or reduced smoking gradually by 75% in the 2 weeks before quitting. Both groups received behavioral support from nurses and used nicotine replacement before and after quit day.

Measurements:

The primary outcome measure was prolonged validated abstinence from smoking 4 weeks after quit day. The secondary outcome was prolonged, validated, 6-month abstinence.

Results:

At 4 weeks, 39.2% (95% CI, 34.0% to 44.4%) of the participants in the gradual-cessation group were abstinent compared with 49.0% (CI, 43.8% to 54.2%) in the abrupt-cessation group (relative risk, 0.80 [CI, 0.66 to 0.93]). At 6 months, 15.5% (CI, 12.0% to 19.7%) of the participants in the gradual-cessation group were abstinent compared with 22.0% (CI, 18.0% to 26.6%) in the abrupt-cessation group (relative risk, 0.71 [CI, 0.46 to 0.91]). Participants who preferred gradual cessation were significantly less likely to be abstinent at 4 weeks than those who preferred abrupt cessation (38.3% vs 52.2%; P = 0.007).

Limitations:

Blinding was impossible. Most participants were white.

Conclusion:

Quitting smoking abruptly is more likely to lead to lasting abstinence than cutting down first, even for smokers who initially prefer to quit by gradual reduction.

Primary Funding Source:

British Heart Foundation.