Table 1

Overview of included trials

Trial*CountrySponsor (affiliation)DesignInterventions (brand/model)
ISRCTN1343952946 47ItalyBAT (Industry-affiliated)Crossover RCTHTPs (Glo1.0, Glo1.1) cigarettes (OB), NRT (Nicorette inhaler)
ISRCTN14301360/UMIN00002498848–51JapanBAT (Industry-affiliated)Parallel RCTHTPs (Glo1.0, Glo1.0M, IQOS) cigarettes (Lucky Strike Regular, Lucky Strike Menthol), tobacco and nicotine cessation
ISRCTN8065190952 53UKBAT (Industry-affiliated)Parallel RCTHTPs (Glo1.0, unknown brand HTP) cigarettes (Lucky Strike Regular), e-cigarette (IS1.0(TT)), tobacco and nicotine cessation
ISRCTN8107576054–60UKBAT (Industry-affiliated)Parallel RCTHTPs (Glo1.1, THD2.4T20), cigarettes (OB), smoking cessation
Dalrymple et al (2022)26GermanyBAT (Industry-affiliated)Repeated measuresHTP (Glo), cigarettes (N491), e-cigarette (ePen 3)
Gee et al (2018)61JapanBAT (Industry-affiliated)Actual use studyHTPs (Glo1.0, Glo1.0M, IQOS) cigarettes (Lucky Strike Regular, Lucky Strike Menthol)
Jones et al (2020)62ItalyBAT (Industry-affiliated)Actual use studyHTPs (Glo1.0, IQOS) cigarettes (Lucky Strike Regular), e-cigarettes (IS1.0(TT))
UMIN00001729763 64JapanJTI (Industry-affiliated)Crossover RCTHTP (Prototype NTVP), cigarettes (unknown brand)
UMIN00002577765–67JapanJTI (Industry-affiliated)Parallel RCTHTP (NTVP), cigarettes (OB), smoking cessation
UMIN00004153968 69JapanJTI (Industry-affiliated)Parallel RCTHTPs (Ploom TECH+, Ploom S2.0, 2 HTPs of unknown brands), cigarettes (OB), smoking cessation
ISRCTN8868243570 71UKJTI (Industry-affiliated)Crossover RCTHTP (HNB2.1), cigarettes (unknown brand)
NCT0370011272 73New ZealandJUUL Labs (Industry-affiliated)Crossover RCTHTP (IQOS), e-cigarettes (JUUL, Myblu, MarkTen Bold Classic, VUSE Solo, PHIX, NJOY Daily), cigarettes (Marlboro Red)
NCT0178068874 75UKPMI (Industry-affiliated)Crossover RCTHTP (IQOS2.1), cigarettes (OB)
NCT0178071476–78PolandPMI (Industry-affiliated)Parallel RCTHTP (IQOS2.1), cigarettes (OB)
NCT0195960779–82JapanPMI (Industry-affiliated)Crossover RCTHTP (IQOS2.2), cigarettes (OB), NRT (Nicorette gum)
NCT0195993283–89PolandPMI (Industry-affiliated)Parallel RCTHTP (IQOS2.2), cigarettes (OB), tobacco and nicotine cessation
NCT0196770679 90–94JapanPMI (Industry-affiliated)Crossover RCTHTP (IQOS2.2M), cigarettes (OB, M), NRT (Nicorette gum)
NCT0196771995–99USAPMI (Industry-affiliated)Crossover RCTHTP (IQOS2.2M), cigarettes (OB, M), NRT (Nicotrol nasal spray)
NCT01967732100–103UKPMI (Industry-affiliated)Crossover RCTHTP (IQOS2.2), cigarettes (OB), NRT (Nicotrol nasal spray)
NCT01970982104–109JapanPMI (Industry-affiliated)Parallel RCTHTP (IQOS2.2), cigarettes (OB), tobacco and nicotine cessation
NCT01970995110–115JapanPMI (Industry-affiliated)Parallel RCTHTP (IQOS2.2M), cigarettes (OB, M), smoking cessation
NCT01989156116–121USAPMI (Industry-affiliated)Parallel RCTHTP (IQOS2.2M), cigarettes (OB, M), smoking cessation
NCT02396381122–125USAPMI (Industry-affiliated)Parallel RCTHTP (IQOS2.2), cigarettes (OB)
NCT02466412126–128JapanPMI (Industry-affiliated)Crossover RCTHTP (CHTP1.1M), cigarettes (OB, M)
NCT02503254129–134PolandPMI (Industry-affiliated)Parallel RCTHTP (CHTP1.0), cigarettes (OB)
NCT02641587135–138PolandPMI (Industry-affiliated)Parallel RCTHTP (CHTP1.2), cigarettes (OB)
NCT02649556139–141USAPMI (Industry-affiliated)Parallel RCTHTP (IQOS2.2), cigarettes (OB)
NCT03364751142–145JapanPMI (Industry-affiliated)Parallel RCTHTP (IQOS), cigarettes (OB)
Caponnetto et al (2018)24UnknownUniversity of Catania (Industry-affiliated)Crossover RCTHTPs (IQOS, Glo), cigarettes (OB)
DRKS00012919146 147GermanyUniversity Medical Centre Schleswig-Holstein (Independent)Crossover RCTHTP (IQOS2.2), cigarettes (Marlboro Gold), e-cigarettes (eGo-T with and without nicotine)
NCT03301129148 149ItalyUniversity of Roma La Sapienza (Independent)Crossover RCTHTP (IQOS2.2), cigarettes (Marlboro Gold), e-cigarette (Blu Pro)
NCT03435562150 151USAVirginia Commonwealth University and NIDA (Independent)Crossover RCTHTP (IQOS), cigarettes (OB), e-cigarette (JUUL)
NCT03452124152 153GreeceNational and Kapodistrian University of Athens (Independent)Crossover RCT+Case Control StudyRCT: HTP (IQOS), cigarettes (Marlboro Red), sham cigarette
Case Control: HTPs (IQOS), cigarettes (unknown brand)
NCT03889990/NCT03995329154–156GreeceAristotle University Of Thessaloniki (Independent)Single-group assignmentHTP (IQOS) #6896157 158BelgiumKU Leuven and Thomas More University of Applied Sciences (Independent)Crossover RCTHTP (IQOS), cigarettes (OB), e-cigarette (Eleaf iStick)
Iokeimidis et al (2021)159GreeceAthens Medical School, Hippokration HospitalCrossover RCTHTP (IQOS), cigarettes (unknown brand), sham cigarette
Lopez et al (2016)160USANIDA and CTP (Independent)Crossover RCTHTP (PAX), CC (OB), e-cigarette (eGo)
Nga et al (2020)161MalaysiaInternational Medical University (Independent)Quasi-experimentalHTP (IQOS), cigarettes (OB), e-cigarette (Aspire AVP)
Phillips-Waller et al (2021)162UKTobacco Advisory Group project grant, Cancer Research UKNon-randomised crossoverHTPS (IQOS), cigarettes (OB), e-cigarettes (JUUL, KangerTech EVOD, Innokin iTaste MVP 2)
Yaman et al (2021)163CyprusNear East University and Mersin City Training and Research HospitalCrossover RCTHTP (IQOS), cigarettes (OB)
  • *Registration ID for registered trials. Author and date for unregistered trials.

  • BAT, British American Tobacco; [C]HTP, [carbon] heated tobacco product; CTP, Center for Tobacco Products, U.S. Food and Drug Administration; JTI, Japan Tobacco International; M, menthol; NIDA, National Institute on Drug Abuse; NRT, nicotine replacement therapy; NTVP, novel tobacco vapour product; OB, participant’s preferred own brand of cigarettes; PMI, Philip Morris International; RCT, randomised controlled trial.