A newly published academic commentary has raised fresh questions about how evidence on vaping for smoking cessation is interpreted and communicated, after researchers identified a pattern of systematic reviews reporting positive results for e-cigarettes but stopping short of recommending their use.
The paper introduces the term “reverse spin bias” to describe situations where authors acknowledge statistically significant benefits in their own analyses, yet downplay or dismiss those findings in their conclusions.
The authors examined 16 systematic reviews on e-cigarettes for smoking cessation published between 2021 and 2025. Thirteen of those reviews found that e-cigarettes were significantly more effective than comparators such as nicotine replacement therapy or placebo. However, only three review teams went on to recommend e-cigarettes as a cessation aid. In the remaining ten, five explicitly advised against their use, while five declined to make any recommendation despite reporting evidence of benefit.
According to the commentary, this disconnect between results and recommendations risks undermining evidence-informed decision-making in both clinical and public health settings.
Five ways positive findings are played down
The researchers identified five recurring narrative techniques used to discount favourable outcomes for controversial treatments such as vaping:
- Discounting the evidence base, by labelling it “limited”, “inconsistent” or “low quality” without formal assessment
- Discrediting primary studies, even when trials showed statistically significant benefits
- Appealing to fear, for example by citing vague future harms not demonstrated in the reviews
- Rejecting the treatment a priori, based on regulatory or ideological positions rather than clinical outcomes
- Omitting findings, particularly where sub-group benefits were observed
While the analysis also looked at medical cannabis for pain management, the authors say the same pattern was clearly visible in vaping research, with multiple reviews acknowledging higher quit rates for e-cigarette users while simultaneously discouraging adoption.
They argue that this form of reporting bias differs from traditional “spin”, which usually involves overstating weak or non-significant results. Instead, reverse spin bias involves under-selling positive evidence, potentially sidelining effective harm-reduction tools.
Implications for the vape sector
For the vape industry, the findings add weight to longstanding concerns that vaping evidence is not always reflected accurately in policy-facing summaries and academic conclusions.
The authors suggest several possible motivations, including pressure to align with prevailing anti-vaping narratives or a desire to improve publication prospects in journals wary of research perceived as favourable to nicotine products. They also point to confirmation bias, where reviewers frame conclusions to fit pre-existing views on e-cigarettes.
Crucially, the paper warns that such practices may have real-world consequences: potentially effective cessation tools risk being overlooked, while data from clinical studies goes under-utilised.
The researchers are calling on journal editors and peer reviewers to pay closer attention to whether conclusions genuinely reflect the underlying results, arguing that stronger scrutiny is needed to prevent reporting bias from shaping healthcare guidance.