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

Objective:
We quantified the proportion of HTP research funded by the tobacco industry and assessed any association with how authors interpreted findings.

Methods:
We conducted a systematic review of the literature through 25 February 2020 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 favorable, neutral, or unfavorable conclusion on HTPs and tobacco harm reduction (THR).

Results:
We retrieved 211 studies, of which 122 (57.8%) had tobaccorelated COIs. No studies with a declared COI were among the 42 studies assessed as against or strongly against HTPs, with 13 among 42 neutral studies (30.9%), and 109 among 127 studies evaluated as in favor or strongly in favor (85.8%). The multivariate odds ratio of being supportive of HTPs was 23.1 (95% confidence interval: 7.3–71.5) 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. The large majority of COI-free studies oppose HTPs. There is an urgent need to fund and sustain independent research on novel tobacco products.