Table 3

Summary of direction of effect in primary outcomes at last follow-up between heated tobacco product and combustible cigarette arms

TrialAffiliationDesignPrimary outcomesRoB (all domains)RoB (exc. BPP)
ISRCTN13439529Industry-affiliatedRCT▼7HighHigh
ISRCTN14301360/UMIN000024988Industry-affiliatedRCT▲16HighHigh
ISRCTN80651909Industry-affiliatedRCT▲19HighHigh
ISRCTN81075760Industry-affiliatedRCT▲1HighHigh
Gee et al (2018)61Industry-affiliatedNRT◄►6HighHigh
Jones et al (2020)62Industry-affiliatedNRT◄►5HighHigh
ISRCTN88682435Industry-affiliatedRCT▼3HighHigh
NCT03700112Industry-affiliatedRCT◄►3HighHigh
NCT01780714Industry-affiliatedRCT▲4HighHigh
NCT02466412Industry-affiliatedRCT▼2HighHigh
NCT02503254Industry-affiliatedRCT▲4HighHigh
NCT02641587Industry-affiliatedRCT▲5HighHigh
NCT02649556Industry-affiliatedRCT◄►8HighHigh
NCT03364751Industry-affiliatedRCT▼1HighHigh
UMIN000017297Industry-affiliatedRCT◄►3HighUnclear
UMIN000025777Industry-affiliatedRCT▲16HighUnclear
UMIN000041539Industry-affiliatedRCT▲15HighUnclear
NCT01780688Industry-affiliatedRCT▼2HighLow
NCT01959607Industry-affiliatedRCT▲2HighLow
NCT01959932Industry-affiliatedRCT▲4HighLow
NCT01967706Industry-affiliatedRCT▲2HighLow
NCT01967719Industry-affiliatedRCT◄►2HighLow
NCT01967732Industry-affiliatedRCT▲2HighLow
NCT01970982Industry-affiliatedRCT▲4HighLow
NCT01970995Industry-affiliatedRCT▲5HighLow
NCT01989156Industry-affiliatedRCT▲5HighLow
NCT02396381Industry-affiliatedRCT◄►8HighLow
Dalrymple et al (2022)26Industry-affiliatedRMS▲9Unclear*Low*
Caponnetto et al (2018)24Industry-affiliatedRCT▲1UnclearUnclear
NCT03889990/NCT03995329IndependentNRTNE†HighHigh
Nga et al (2020)161IndependentNRT▲1HighHigh
Lopez et al (2016)160IndependentRCT◄►6HighHigh
DRKS00012919IndependentRCT▼1HighHigh
NCT03435562IndependentRCT▼1HighHigh
NCT03452124IndependentRCT+CCS▲4HighHigh
Phillips-Waller et al (2021)162IndependentNRT▼7HighHigh
aspredicted.org #6896IndependentRCT◄►5UnclearUnclear
NCT03301129IndependentRCT▲2UnclearUnclear
Ioakeimidis (2021)IndependentRCT▲6UnclearUnclear
Yaman et al (2021)163IndependentRCT◄►24UnclearUnclear
  • Effect direction: ▲=HTP had a positive effect compared with cigarettes; ▼=HTP had a negative effect compared with cigarettes; ◄►=mixed or conflicting effects.

  • Numbers next to arrows describe number of primary outcomes within each synthesis.

  • Trial quality: RoB (all domains)=overall risk of bias based on all domains; RoB (exc. BPP)=overall risk of bias based on all domains except blinding of participants and personnel.

  • *This is excluding selection bias, which could not be assessed in this study.

  • †Not estimable due to lack of cigarette arm.

  • BPP, blinding of participants and personnel; CCS, case-control study; HTP, heated tobacco product; NE, not estimable; NRT, non-randomised trial; RCT, randomised controlled trial; RMS, repeated measures study.