Persistent pain is associated with a number of psychiatric diagnoses. For example, depression, anxiety and substance use disorders are common among people with persistent pain. Frustratingly, the conditions often exacerbate one another. In the case of substance use disorders—including tobacco use—a potential self-medication component must also be considered. Unsurprisingly, researchers have observed a strong relationship between smoking and physical pain, although it remains unclear if there is a direct causal link.

Accordingly, a research group based at Syracuse University with a lengthy publication record on the relationships and mechanisms that bind smoking, nicotine and pain recently released a study that assesses the likelihood of e-cigarette use among smokers with persistent pain. Early in the article, the authors provide multiple sources that describe the analgesic effects of nicotine and their potential contribution to the association between smoking and persistent pain. They also note that pain is a strong contributor to the urge to smoke, to smoking behavior and dependence. While no one suggests using tobacco for pain management, the reality is that persistent pain—whether physical or psychological—can cause people to use whatever means available to diminish their discomfort, especially if they do not have access to other medical options or achieve inadequate results with other treatments.

In light of this, the authors conducted a cross-sectional survey of 301 smokers who regularly smoke at least ten cigarettes per day and indicated that they were very motivated to quit within the next 30 days. The survey asked the participants to report their use of other tobacco products, pain status during the preceding two weeks, psychiatric comorbidities and demographic characteristics. Slightly less than a quarter of the sample reported significant pain during the preceding two weeks, and participants were more likely to report pain if they were white, unemployed or reported higher levels of depression. Smokers reporting pain also had more than four times the odds of having used an e-cigarette in the previous seven days, compared to smokers without pain.

With respect to specific findings, the authors found that participants who reported pain had greater odds of lifetime e-cigarette, cigar, pipe and hookah use, compared to participants who did not report pain. These results hint that smokers who report pain are drawn to inhaled products over oral ones (such as snuff, dip or snus). This is likely because—as the authors note—nicotine reaches peak blood levels most quickly via inhalation. They also cite studies that show smokers find it more difficult to control their nicotine intake when using oral products. This is one reason that smokers report being more likely to consider switching to e-cigarettes than an oral product. And moreover, both of these properties may be attractive to a person experiencing pain.

Overall, the study found that smokers who report pain exhibit higher cigarette dependence and smoke more cigarettes per day, on average, than smokers who do not. Also, those who reported pain were more likely to report use of multiple tobacco products throughout their lifetime and current e-cigarette use than smokers who did not report pain. Since smokers experiencing pain display higher dependence, they may find it more difficult to quit smoking. However, their higher likelihood of current e-cigarette use combined with e-cigarette’s similarities to combustible cigarettes suggests that e-cigarettes may be an appealing harm reduction tool for these smokers, as they are a close substitute.

Powers et al.’s expertise is evident in their discussion, which is pragmatic and accurate in its assessment of this study’s contextual meaning and limitations. While the findings are interesting and based on valid methods, the study’s limitations nevertheless necessitate a narrow interpretation of the results. First, it is important to remember that, due to the study design, causation cannot be determined. Accordingly, a related limitation is that the authors present results for lifetime use of alternative tobacco products, among them e-cigarettes, but they only report current use statistics for e-cigarettes. Since the authors retrospectively and simultaneously assessed product use and pain, it is impossible to know, for example, the magnitude of lifetime product use, how multiple product use impacted total nicotine consumption, whether pain preceded product use or if participants used combustible cigarettes and other tobacco products concurrently. The challenge with using lifetime use (i.e. ever-use) instead of current use in tobacco studies is that it is much more difficult to hypothesize a clinical or policy intervention based on these kinds of statistics. The intricacies of interpretation are also important because misinterpretation can lead to unsuccessful, and sometimes downright harmful, assumptions and interventions.

In sum, Powers et al. highlight avenues that nicotine and tobacco researchers should continue exploring. Indeed, this line of research has great potential to guide the application of harm reduction tactics for smokers who also experience persistent pain. For smokers struggling with pain management, their pain may decrease their willingness and ability to quit. However, if pain exacerbates a smoker’s dependence on nicotine, e-cigarettes’ similarity to combustible cigarettes and decreased risk profile, may offer harm reduction benefits beyond decreased risk of smoking-related illnesses.