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Use of electronic-cigarettes was associated with a lower rate of smoking cessation at 6 months among recently hospitalized smokers who said they planned to quit, compared with non-users in a secondary analysis of a large randomized trial.

Six months after discharge, the participants who used e-cigarettes had a lower incidence of smoking cessation than those who did not use e-cigarettes, wrote Nancy Rigotti, MD, director of the Tobacco Research and Treatment Center of Massachusetts General Hospital in Boston, and colleagues.

In an analysis of 237 propensity score-matched pairs, 10.1% of e-cigarette users had quit smoking at 6 months, versus 26.6% of non-users (risk difference -16.5%; 95% CI -23.3% to -9.6%).

Three months after hospital discharge, 28% the 1,357 study participants reported e-cigarette use, and of those, less than half said they used e-cigarettes regularly -- a low rate that could have affected the findings, Rigotti and colleagues wrote.

The observational analysis is published online in

"We found that patients who used e-cigarettes were actually less likely to succeed in quitting compared to those who did not, which is the reverse of what we might expect to see if e-cigarettes help people quit," Rigotti told 乌鸦传媒 Today.

"But a big caveat is that we don't know how they were using them. The e-cigarette users may have been the people who were having the most trouble quitting."

Rigotti noted that while almost 70% of the study participants who used e-cigarettes said they were doing so to help them quit combustible cigarettes, the frequency of use ranged from daily to just once a week.

"I think the message of this paper is that using e-cigarettes infrequently or using them with cigarettes is just not an effective way to quit smoking. Many of these people didn't even use e-cigarettes once a day. People who have success with [approved] smoking-cessation medications use them regularly. That is probably how e-cigarettes need to be used if they are going to be effective."

The analysis included participants in the randomized , conducted to assess the efficacy of a post hospital-discharge smoking-cessation intervention. All 1,357 participants received tobacco-cessation counseling while hospitalized, and were randomized to receive a tobacco treatment recommendation consisting of instructions on accessing a telephone quit-line and medication recommendations (controls) or the same intervention with free access to a smoking-cessation medication.

Self-reported e-cigarette use was assessed 1 month and 3 months after hospital discharge, and biochemically validated tobacco abstinence was assessed 6 months after discharge.

The association between e-cigarette use and quitting varied between intervention patients given free access to medications (7.7% versus 29.8%; risk difference, -22.1%; 95% CI, -32.3% to -11.9%) and control patients (12% versus 24.1%, 95% CI, -21.2% to 2.9%) (P for interaction = 0.143).

"Because of the study's observational design, in which e-cigarette use was self-selected, unmeasured confounding could explain the findings, and a causal relationship cannot be inferred from these data," the researchers cautioned, adding, however, that E-value calculation indicated that only a very strong unmeasured confounder could explain the findings.

Other study limitations included the lack of information on e-cigarette type and lack of detailed information on frequency of use.

"Despite the limitations inherent in its observational design, this study illustrates how e-cigarettes, which are widely available commercially, are being used in a common clinical situation (a cessation attempt after hospitalization)," the researchers wrote.

"In this setting, the use of e-cigarettes intermittently and concurrently with other cessation aids did not seem to aid quitting and may have hampered it. The possibility remains that e-cigarettes can promote tobacco cessation if they are used regularly and as a complete replacement for cigarettes, which is how conventional cessation medications are recommended for use. Future research, particularly randomized controlled trials, is needed to address this critical question."

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