Consistent with other studies,a longer history of cigarette smoking predicted worsening respiratory symptoms and decreased chances of improvement, independent of P30D cigarette smoking, underlining the importance of cigarette smoke exposure in the development or worsening of respiratory symptoms. The consequences of cigarette use were the same regardless of which additional tobacco products were used. As shown previously, dual users of cigarettes and e-cigarettes smoked cigarettes as frequently as exclusive cigarette smokers,their respiratory response to cigarette smoking intensity was essentially the same as exclusive cigarette users, and they had indistinguishable risk for symptom worsening.We found no evidence to support the idea that dual use of cigarettes and e-cigarettes carries higher risk for respiratory symptom worsening compared to exclusive cigarettes for the symptom outcomes we examined. This contrasts with increased risk of dual use in the analyses of PATH Study data reported by Reddy et al,an analysis that involved a different period , and adjusted only for demographics; we doubt the finding reported by Reddy would have remained statistically significant after adjustment for the multiple confounders included in the present analysis. In contrast, respiratory symptom risk for exclusive users of other tobacco products was significantly lower than for cigarettes, and was largely not significantly different from never or former tobacco users. The finding for e-cigarettes contradicts two cross-sectional studies of tobacco use and respiratory symptoms, one using PATH Study W2 data18 and one using W3 data,greenhouse tables both concluding that there was an association between e-cigarette use and wheezing. These studies examined the association with each item on the respiratory index and neither adjusted for cigarette smoking history or marijuana use.Based on the present study findings— lack of a crude dose-response for e-cigarette frequency illustrated in Figure 2 and the confounding analysis in Table 2—we conclude that the reported associations in these papers were likely spurious, primarily because of the failure to adjust for cigarette smoking history.
Our supplemental materials include a method for determining cigarette pack-years from PATH Study data to support the inclusion of this important confounder by other users of these data. The longitudinal results seem contradictory if the reference of focus is never users—ecigarette users are significantly more likely to have symptoms worsen at one cut-off level and significantly more likely to have symptoms improve at another—an example of how results for ecigarette users may be sensitive to how health outcomes are determined. But another viewpoint is that potentially reduced harm tobacco products are judged also by how health risks of the product compare to the health risks for cigarette smokers. With cigarette users as the referent category, the analysis suggests that exclusive e-cigarette users are less likely to have their respiratory symptoms worsen, along with consistent findings , than they are more likely to have their symptoms improve. In sum, with respect to short-term changes in functionally-important respiratory symptoms, the results suggest risk for exclusive e-cigarette users are intermediate–increased harm compared to never tobacco users, but reduced harm compared to cigarette users. Cigar smokers had consistently lower risk for functionally-important respiratory symptoms compared to exclusive cigarette smokers, as was previously reported for some of the single respiratory symptom items in another PATH Study report.Cigar smoking has been associated with higher mortality from respiratory disease and lung cancer,increased risk for diagnosis of lung cancer and COPD,decreased lung function and airflow obstruction,and respiratory symptoms.In all studies including cigarette smokers, risks associated with cigars were lower than for cigarettes; former cigarette smokers switching to cigars had higher risk vs. those who had smoked only cigars.Respiratory symptom risk among hookah smokers has not been studied extensively but was intermediate between never smokers and cigarette smokers in one study.Lower symptom risk with exclusive cigar use may be explained by reduced smoke inhalation.In contrast to cigarettes, cigar tobacco is fermented, and many cigars are smoked with lower frequency.
Cigar smokers also tend to inhale less deeply because of smoke alkalinity which also enhances oral nicotine absorption. Only 15% of exclusive cigar smokers reportactively inhaling the smoke, compared to two-thirds for users of both cigars and cigarettes .Marijuana was associated with functionally-important respiratory symptoms, consistent with 8 of 10 previous studies.The findings are backed by research involving dual users of marijuana and cigarettes showing higher puff volumes, deeper inhalation, and greater tar retention from marijuana vs. cigarettes,animal research documenting pulmonary cell changes with chronic marijuana smoking, and prospective research showing changes in lung function among marijuana smokers.One study showing an association between e-cigarette use and cough among young never cigarette smokers, failed to adjust for marijuana use in the multivariable model . Another study of adult PATH Study W4 data found vaping with marijuana to be associated with wheezing , consistent with our findings.Two other studies of youth, one using PATH Study data, have shown that the e-cigarette—respiratory outcome is confounded by marijuana use and marijuana vaping.Clinicians need to be aware of the association between marijuana use and respiratory symptoms as use increases.The study strengths include a nationally representative sample, a validated respiratory outcome related to functional impairment, and adjustment for multiple confounding influences. Limitations include small numbers in some product groups, increasing the probability of a chance finding. Because switching from cigarette smoking to exclusive e-cigarette use is an uncommon event, randomized e-cigarette switching trials may be required to better assess how e-cigarette substitution affects wheezing symptoms among adult cigarette smokers. Risk of marijuana smoking on respiratory symptoms may be underestimated because marijuana use may have included non-combustible products.Relying on self-report of COPD may have resulted in some who were unaware of their diagnosis being retained in the study.
The findings relate only to short-term changes in wheezing and nighttime cough, not other bothersome symptoms , longer-term symptom effects, relation to respiratory disease onset, or vaping-related acute lung injury—medical issues that underline concern about any inhaled product use. The analysis included many comparisons and nevertheless employed a p-value of 0.05; the associations reported should be confirmed in other samples. Finally, future analyses with the latest available data from the PATH Study may provide a more refined look at the questions addressed in the present study. In summary, this study of a nationally representative sample of US adults without severe respiratory disease found an association between cigarette smoking and functionally-important respiratory symptoms – and substantially less evidence of associations between respiratory symptoms and exclusive non-cigarette tobacco product use. Early use of substances has been associated with more severe addictions and subsequent poor treatment outcomes . Early age at first substance use can lead to different addiction use trajectories, including early-onset and severe SUD symptoms persisting into adulthood, early-onset in adolescence that improves in adulthood,vertical farming and SUD symptoms emerging later with varying degrees of severity and persistence . Additionally, early age at first substance use not only negatively impacts mental health outcomes, but it also influences the addiction recovery process. Earlier age at inaugural substance use exerts a significant influence on later severe SUDs and constitutes a risk factor for comorbid mental health issues . Early age at first substance use can also extend the addiction recovery process , influence relapse frequency , and suicide attempts . To date, available evidence on associations between age at first substance use and later SUD varied across study populations, and research conducted in regions other than North America and Europe, especially sub-Saharan Africa is scarce . However, the majority of SSA countries is disproportionally affected by fragile security and armed conflicts ; which are among factors for proliferation of psychoactive substances in the region . This dearth of research may obstruct interventions toward the growing substance use issues, such as alcohol use disorders and subsequent deaths among youth in Africa .
Globally, substantial evidence links first alcohol use, before 18 years old, with higher alcohol and other drug disorders . In Canada, individuals consuming alcohol between the ages of 11 and 14 had more risk for developing alcohol disorders compared with those who started drinking alcohol after the age of 19 . Donoghue et al. in a study conducted in the UK likewise found a strong association between age of the first alcohol consumption, before the age of 15, tobacco use, lower quality of life, and emergency room admissions for alcohol use disorders among adolescents. Similarly, a recent systematic review of prospective studies highlighted the impact of early first alcohol use on future alcohol use disorders . In a birth cohort study, Newton-Howes and Boden demonstrated that early age of first drug use significantly increased the risk for later alcohol use disorders, nicotine dependence, and illicit drug dependence. However, after controlling for covariate factors, such as family living standards, ethnicity, and childhood sexual abuse, earlier first substance use was found to have no significant associations with these SUDs . In an Australian study, young age substance exposure was associated with later polydrug use, such as methamphetamine and heroin . In contrast to the above evidence, other research found no statistically significant associations between early-age substance use and later SUD . A few studies conducted in SSA reported the age at onset of only two types of psychoactive substances, alcohol , and tobacco . In youth tobacco surveys from nine Western Africa countries, Veeranki et al. found that the age of smoking onset was as early as 7 years old. Osaki et al. in a Tanzanian secondary school and college students aged 15–24 found that the age of alcohol consumption was as early as 10 years old. Contextual factors for alcohol use onset included exposure to a stressful environment, social events, and home alcohol consumption under the influence of parents, relatives, peers, and intimate partners . Likewise, a systematic review for cross-country comparison by Townsend et al. demonstrated that tobacco use primarily began in late adolescence and early adulthood in SSA. However, Townsend et al. found no association between tobacco use and socioeconomic status or urban/rural difference. The strength of the association be-tween first substance use to SUD seems to be moderated by contextual factors. Variations in the strength of associations between first substance use and SUD may be partially explained by environmental factors, such as life adversity and conflict-related psychology strains . In the recent UK Millennium Cohort Study of 10,498 11-year-old participants, having a friend who drank was a strong risk factor for increased alcohol use patterns . Besides, McCann et al. indicated that relationships, including higher levels of parental control and lower levels of child openness to parents, were linked with less frequent alcohol use. Furthermore, child-hood traumatic experiences in the forms of severe and mild physical abuse significantly correlated with an earlier age at first alcohol consumption, as well as illicit and poly drug use . Other factors, such as premorbid cognitive deficit early-age major depression , bipolar disorders , and impulse control influence early-age substance use and addiction trajectory following first substance. Additionally, interactions between premorbid mental health deficits and the effects of substance use on cognitive development may influence the early substance use onset and rapid spirals into substance dependence . Overall, there is little and inconsistent evidence on the association between early age at first substance use and later severe addiction issues worldwide. While the associations between PTSD and SUD are well documented, little is known about how young age substance use coupled to PTSD contributes to later severe addiction. Likewise, PTSD has been studied somewhat in SSA and substantially in Rwanda ; however, there is minimal data on associated substance misuse. The identified studies focused on a few substances and did not examine the transition from first use to addiction and contributors to later addiction severity. The study used consecutive sampling techniques to screen 362 participants who were referred to the study, only 342 of whom were eligible, and 315 consented to participate in the study. Given that addiction issues do not have any known seasonal fluctuations, consecutive sampling was the most reliable form of non-probability sampling, which can achieve a representative sample within a short time . Participants were included in the sample if they were aged 18 years old and over, had been diagnosed with any substance use disorder, presented for intake or relapse assessment, able to answer questions, and willingly provided consent.