Introduction:
Tobacco companies are investing massive amounts of money to support research on heated tobacco products (HTP).

Objective:
To quantify the proportion of HTP research funded by the tobacco industry and to assess any association with how authors interpreted findings.

Material and Methods:
We conducted a systematic review of the literature through 23rd February 2022 in Pubmed/Medline, Embase and the Cochrane Library to identify all publications focusing on HTPs (PROSPERO 2020: CRD42020137394). For each study, reported tobacco industry related conflict of interest (COI) was identified based on authors’ affiliations, acknowledgements, funding, and COI disclosure. Two trained reviewers, blinded to information on authors, independently evaluated the conclusions of the abstracts to categorize them as providing either a favourable, neutral, or unfavourable conclusion on HTPs and tobacco harm reduction (THR).

Results:
We retrieved 514 studies, of which 320 (62.3%) had tobacco-related COIs. Six studies with a declared COI were among the 196 studies assessed as against or strongly against HTPs (3.1%), with 20 among 102 neutral studies (19.6%), and 168 among 216 studies evaluated as in favour or strongly in favour (77.8%). The crude odds ratio of being supportive of HTPs was 36.6 (95% confidence interval: 21.9 to 61.3) for studies with a COI.

Conclusions:
The existing body of published research on HTPs is dominated by studies conducted or supported by the tobacco industry, with evidence of bias in their conclusions. The large majority of COI-free studies oppose HTPs. There is an urgent need to fund and sustain independent research on novel tobacco products.