Effect of integrated smoking cessation treatment on smoking intensity among persons who receive opioid agonist treatment

Background
Among persons with opioid dependence, an estimated 90 % smoke tobacco. Tobacco smoking causes increased morbidity and reduced life expectancy among opioid-dependent persons. In addition, chronic obstructive pulmonary disorders caused by tobacco smoking may increase the risk of opioid overdose. At the same time, studies have indicated that smoking cessation is more challenging to achieve among opioid-dependent persons. Possible explanations are opioid nicotine interactions, a pro-smoking social environment, and a lack of support from healthcare workers. This study aimed to test if an integrated smoking cessation intervention would increase the likelihood of participants reducing their smoking intensity by at least 50 %.
MethodsWe conducted a randomized controlled trial of integrated smoking cessation interventions at outpatient clinics providing opioid agonist treatment to persons with opioid dependence in the Norwegian cities of Bergen and Stavanger. The trial was completed in November 2023. Participants were randomized 1:1 to receiving a 16-week smoking cessation intervention with a weekly supply of nicotine replacement products and weekly short behavioural interventions or receiving opioid agonist treatment as usual (control group). Participants who smoked cannabis mixed with tobacco were asked to estimate the cannabis-tobacco ratio they used, and the tobacco portion was counted in the total cigarette count.
ResultsTwo hundred fifty-nine persons were included in the study. Missing values at the end of the trial are set equal to baseline. The mean number of cigarettes smoked per week for all participants at the start of the trial was 81.8 (sd 56.6) compared to 63.4 (sd 50.1) at week 16.  In the intervention group, 30% of the participants reported reducing the number of cigarettes smoked per week by at least 50 % compared to 17 % in the control group. Intention to treat analysis, using logistic regression,  indicates that participants who received the intervention had an odds ratio of 2.07 (95 % CI 1.14; 3.75, p =0.017) of at least reducing the number of cigarettes smoked by 50 % compared to the control group.
ConclusionsOur study indicates that integrating smoking cessation therapies at opioid agonist treatment clinics is an effective measure which can help opioid-dependent persons reduce the number of cigarettes smoked by at least one-half. While smoking cessation has the greatest impact on smoking-related diseases, a reduction in smoking intensity will reduce the risk of such diseases. Without interventions, the smoking cessation rates among persons with opioid dependence are negligible. Previous studies indicate that persons who want to quit smoking need several attempts to successfully quit smoking.  In line with this finding, integrating smoking cessation therapies at opioid agonist treatment clinics could provide patients with the possibility of repeated quit attempts, increasing the probability of quitting smoking.