Offer of a menu of different nicotine substitute products to REduce Tobacco Use iN pEople living with HIV (RETUNE): a protocol for a pragmatic randomized trial within the Swiss HIV Cohort Study
 Thanks to highly effective antiretroviral therapy, people living with HIV (PLWH) now have a near-normal life expectancy. Attention has therefore shifted from HIV-related complications to non-communicable diseases, particularly cardiovascular disease and cancer. Tobacco smoking is a major driver of both, and smokers with HIV now lose more life years to smoking than to HIV itself.
The RETUNE trial will test whether offering a menu of nicotine substitute products (e-cigarettes, nicotine pouches and nicotine patches) helps smokers in the Swiss HIV Cohort Study (SHCS) reduce tobacco use. The offer will be made to all smokers, regardless of their willingness to quit. Participants will be recruited at the SHCS centres in Basel, Bern, Geneva, Lausanne, St. Gallen, Zurich and Aarau. A participant advisory board supported every phase of the project so far, from planning and funding to intervention design, consent forms, protocol and this manuscript.
RETUNE is a multicentre, pragmatic, 1:1 randomised superiority trial using the Trials-within-Cohorts (TwiCs) design. Eligible participants are randomised within the ongoing cohort. Those allocated to the intervention are informed, may accept or decline the offer, and sign an additional intervention consent. Those allocated to the control arm are not informed about the trial. They continue to receive usual care within the cohort, and their routinely collected data serve as the comparison.
In the intervention arm, participants can choose among the nicotine products, provided free of charge for six months, in addition to usual smoking cessation care. The primary hypothesis is that this preference-based menu is safe and superior to usual care alone for reducing smoking after six months. The primary endpoint is self-reported abstinence from smoking in the past seven days at six months. Secondary endpoints include BMI and cardiovascular events. The target sample size is about 970 participants.
RETUNE will provide evidence on an “opt-out” approach to offering nicotine substitutes. It also shows how a trial can be embedded efficiently in a nationwide cohort through the TwiCs design.