Two main findings of the study and their key implication are discussed below before discussing the results. The first main result of the study is that it is feasible to collect the intended information using the described inclusive methodology: an observational study combining information laboratory analysis of NPS samples and data from online surveys, both provided by online-recruited participants from a stigmatised population in a naturalistic setting. The second main finding of the study is that up to 13 different NPS were identified that could not be related to any previous peer-reviewed study from the studied literature database. The literature review was conducted after analysing the study results and included only the publications that mentioned the substances as NPS, sometimes discarding a significant number of publications providing relevant knowledge about substance pharmacology. To scale the results, 541 NPS were reported to the UNODC early warning advisory on new psychoactive substances in 2019. However, the number of newly identified NPS at a global level amounted only to 71 (including five whose effect has not yet been determined).
These two findings are further discussed during this section, specifying the actual study feasibility and commenting on the evidence obtained to provide further insight into its potential use.
After discussing the study's main findings, the reported results will be discussed in the same general order as they have been presented. The study participants, the study sample of analysed NPS with reported use by the participants, and the general feasibility of the study are discussed below.
The study procedure provided samples similar to the sizes reported when applying clinical methodologies. Most of the screened candidates (81.2%) failed to become enrolled participants (n = 35 18.2%). Nearly half of those enrolled (n = 35 100%) (n = 17; 48.6%) could fulfil all the designed procedures. This result puts the losses from the screening process into perspective, as the participant retention is acceptable considering the high demands from the study and its only reward being a limited free sample testing with a drug checking service. In the most similar online surveys studied, the response rates were close to 20% (increasing up to 80% in certain conditions not applicable in this context). On the contrary, our study was more demanding than the typical online survey with comparable characteristics described in the literature, leaving candidates' losses among the expected or better (64).
The participants of our study reported the same socio-demographic characteristics as the consistent descriptions of the population of e-psychonauts described in the literature (1, 65–68). Nonetheless, as the research's main goal was centred on combining reported information collected using online techniques and analytically confirming the reported expectations of the samples' content, the study was designed in a way that the participants mentioned above' characteristics outcomes were part of the screening and eligibility process (40).
Including and giving visibility to the contributions of people who use drugs is also essential to reduce stigma. The stigma is reduced when positive representations of the stigmatised reality become more prevalent. The importance of reducing stigma and its adverse effects has been well established (69–71). The statement mentioned above, however, might be controversial, as the generic negative representation of drug use has been used as a universal prevention strategy for drug use.
The designed methodology also intended to further participants promote a symmetrical dialogue with the researchers, which might increase internal data validity by contrasting the research framework with the participants' narrative (47, 70, 72). Inclusivity also facilitates knowledge empowerment of the study participants and promotes de development of citizen science, a goal set by the European Union to promote civil society participation. Increased participation would also accelerate the introduction of patient-reported outcomes that have shown to improve the obtention of conventional methodologies outcomes obtained in clinic settings (15, 73, 74).
Changing the focus from the participants' sample size to the primary sample of the research, we observe similar results. Of the total surveys (n = 136; 100%) that were intended to correspond to a submitted substance sample, more than two-thirds (n = 92; 67.6%) were received, and its correspondence to a valid substance characteristics survey was successfully determined. This percentage also represents the proportion of samples that were expected to be submitted and finally could be analytically identified and conformed to the comparison sample group for assessing biases due to procedure fulfilment.
Finally, the sample group that was defined by identified substances corresponding to fully reported surveys (both substance characteristics and self-administration surveys) consisted of 54 samples. By meeting the criterion mentioned earlier, we considered that more than half (58.7%) of the analysed samples could be labelled as confirmed NPS (comparing the reported expected content with the actual analysis result of a given sample). From these 54 confirmed NPS, 40 (74.1%) different substances were identified. We considered this a very high number of different identified NPS as it is not so far from the new NPS discovered yearly. For example, in 2020, 70 emerging NPS were identified for the first time (75).
No statistically significant differences in the data collected were detected (n = 54 and n = 92) when exploration of possible intervention biases due to reported analytical results back to the participant and receiving a fulfilled self-administration report. That suggests the absence of selection or completion bias and allows the reasonable discussion of all analysed samples' characteristics.
Regarding the reported sample origin, the most commonly reported was Europe, where point-of-care drug checking services are not as prevalent as in North America (76, 77). It is also remarkable that none of the samples allegedly obtained from the United States was detected as synthetic opioids, contrasting with the prevalence of these NPS observed using seizure data (4)
The most common substance provider was a trusted dealer (55.6%). Some studies report consistent findings, such as high levels of trust regarding regular "dealers" (78). However, other studies report inconsistent results, such as identifying distrust in the drug market as the primary motivation to use drug checking services and questioning the motivational effect of offering drug checking services to a group of participants that mostly report trusting their dealers (13, 79).
Regarding the setting in which the samples were acquired, the clear predominance (66.7%) of traditional internet websites (surface web) is inconsistent with previous reports describing the everyday use of encryption technology (darknet) and cryptocurrency as the usual acquisition settings (80). However, our results are consistent with previous research from drug checking services, showing the predominant use of surface websites to purchase emerging NPS (37).
This data proves that this study design is feasible, as in possible to execute. The narrow interpretations of the data discussed to this point would not encourage further research to consolidate this exploratory methodology. Thus, the drug checking service results and the literature review will be discussed afterwards.
Drug analysis laboratories are the key source of reliable and sound scientific information and data (81). Therefore, in this study, an off-site fixed laboratory equipped with GC/MS LC/MS was used to provide the additional reliability needed to cover the evidence gap, compromising in a delayed report of the analysis result to the user compared with other drug checking methodologies (34).
Most of the samples sent and analysed at the laboratory (n = 79; 84.8%) contained only the active compound that the participants expected, suggesting that the purchased NPS of the study participants seemed to be less adulterated than other participants in other settings, such as general users of drug checking services expecting to analyse traditional drugs. The adulteration of a traditional drug like MDMA, for example, is among the lowest, ranging from 10 to 50% (21, 82, 83). Our research found that only 13% of the total analysed samples were adulterated with other interfering active compounds or the expected substance was not present.
Reported information on the surveyed expectation of the participant samples' composition was also compared between both sample groups. Statistical Fisher's exact test did not indicate any difference, but it was noticeable that most participants expected the analysis to confirm their idea about the composition of their submitted sample.
When conducting the same statistical procedure in a correlation table, it pointed out that the given answers could not be entirely explained by randomness. Within a confidence interval of 95%, participants seemed able to predict if the sample contained only the substance they expected or was adulterated in some way.
However, more robust statistical methods could not be applied due to the limitations of the responsible data, and interpretation of participants' prediction capabilities needs to be interpreted conservatively. Despite its potential use in many scenarios, such knowledge may provide a false sense of security, as its reliability is still compatible with severe negative consequences.
From this point, we will refer to the previously mentioned 40 different NPS circumscribed to the sample group that fulfilled all the procedures established in the study protocol. The primary process that could provide information on the impact of that outcome was the reported outcomes review of scientific publications incorporating peer-reviewing methods.
Of the 40 different detected NPS, the literature review failed to find previous publications regarding 13 different identified NPS. Furthermore, the literature review also found no previous publications reporting the subjective effects of the reported NPS for another 12 identified NPS.
Even though our literature review did not find previous peer-reviewed publications regarding the identified substances used as NPS, it is widely known that international organisations such as EMCDDA or the UNODC report findings on these concrete fields of general drug use topics. Their contributions have not been acknowledged in this publication until this point. Maintaining the focus on the study goal of covering a well-described evidence gap has been the only reason to postpone their commentary (10, 11). The study results will be discussed in light of these relevant but not peer-reviewed reports. We will focus on the reports from the UNODC, as this is the only agency that provides data worldwide, refraining from commenting on the multiple exciting publications from the EMCDDA to avoid centring what ought to be a global discussion in Europe.
Of the 40 different identified substances, 5 (12,5%) had been previously scheduled by the UN: 2C-B (schedule II), 3-MeO-PCP or 3-methoxyphencyclidine (Schedule II), Etizolam (Schedule IV), 4-FA (schedule II) and DOC (schedule I) (84). None were from the 13 substances with no previous literature found in our review, nor the 12 substances with no previous reports of their subjective effects found in the same literature review. The literature review results suggest that the study has identified 13 previously unknown substances in the scientific community. However, the literature review presents limitations, and the authors might have missed some previously published knowledge. However, the likelihood of considering these 13 substances as previously unreported on official channels increases when considering the following result. EMCDDA early warning systems and UNODC have been searched for any reference to these substances without finding any results. Finding only results on google from vendors and online forums or informative platforms (Directive of the European Parliament and Council, 2004; EMCDDA, 2020; The Council of the European Union, 2004). There is, thus, the possibility that this paper is reporting for the first time in a scientific or formal channel the use of the following substances as NPS: 4C-D, 4-ACO-MALT, BOD, Methallylescaline, 25E-NBOH, 3-HO-PCE, 4-ACO-MET, DOF, DOiP, MEAI, MiPT, MXPr, O-Desmethyltramadol.
It is important to note, however, that precisely the only opioid identified in our study as NPS (e.g., O-Desmethyltramadol) has to be regarded in the light of several facts necessary to provide an adequate contextualisation. The O-Desmethyltramadol (n = 1; 1.1%) has mainly been researched, and numerous publications provide original empirical data regarding its human pharmacology. However, none of the mentioned publications considered the substance as NPS or recreational drug. That is the case because o-desmethyltramadol is an active metabolite of tramadol, a widely prescribed opioid(85, 86). So, in this context, it must be acknowledged that the significant overlapping of knowledge required from the metabolite of approved medication and the knowledge required from a substance being used for its psychoactive properties with its additional risks of abuse, overdose, and addiction. However, some new research is also warranted regarding its use as NPS and its potential new benefits and harms.
This study likely provides the first reports regarding the use of up to 13 substances as NPS, increasing the potential number of detected NPS considerably after its publication. However, this interpretation will have to be tested with potentially unpublished information or publications missed by the literature review. Regardless, a discussion of where this new methodology would be positioned in the current landscape of the NPS research field is warranted.
This study provides another innovative methodology that can benefit from the technological innovations of software development. In this regard, innovation in this direction can be seen as an alternative to developing methodologies such as data scraping. Promoting inclusivity, empowering citizen science, and open-source collaboration instead of raising ethical concerns about privacy and data ownership.
The study has not outperformed the early warning systems as forum data scraping has done almost 4:1 but provides more reliable data and is comparable to the number (more than half) of substances detected yearly by official institutions such as UNODC (75). However, for this methodology to have a real scientific impact, it needs to be coupled with methodologies with external validity. Studies such as wastewater analysis can provide the capacity to make prevalence estimations of the general use of the newly identified NPS, triaging anecdotes from the early detection of new trends (87, 88).
Despite all the potential that can be imagined, it is essential to remember that this study is only an experimental, observational design(34). We hope, however, that at least the study can provide the early methodological guidance that observational studies can provide according to the Cochrane guidelines, informing the development of future designs based on the time-tested strengths and weaknesses (89).
After discussing the potential and dependency of the study, a proper discussion of its limitations is warranted.
The study has several limitations intrinsic to its design, representing choices consciously made by the research team to overcome the critical limitations affecting previous research in the field. Other limitations, however, reflect avoidable shortcomings of the study implementation or execution, from which some might be solved with experience and others with increased funding.
Another restriction of the possible outcomes obtained by this study design is related to the sample size. While consisting of a reasonable number of participants for a clinic setting, generalisation of the results to the original population is unsuitable. Thus, more established NPS-monitoring methodologies that work with larger samples may complement our designed method. These studies are already being used successfully by many research teams and networks around the globe. One of those monitoring methodologies is wastewater analysis, which can provide analytical confirmation of substances from a larger sample of collected data. However, because the sample size also requires other methods to signal which chemical compounds might be present, the screening process may use a narrow range of substance comparison samples (87, 90, 91)
The main limitation regarding the main study finding is the lack of external validity and, thus, the impossibility of extrapolating the presented results from our NPS samples to any significant population. Only time or the contribution to another study design, such as wastewater analysis, can consolidate the relevance of this crucial finding.
Another limitation regarding the study feasibility, the other key finding, is the difficulties that might arise when trying to replicate the study design, as the conversations and inclusivity process done with members of the online communities where NPS use is discussed. Then the participants might have benefitted from some idiosyncrasies poorly translated in the methodology, study protocol and supplementary materials.
The inability to directly observe and confirm the participants' behaviour is a limitation to the reliability of the data from the questionnaires. The researcher's physical absence, however, makes the study feasible for many reasons.
Another limitation is the accumulation of methodological innovation. When the study design is too different from other studies, its capacity to connect its results to the shared pool of scientific knowledge becomes limited, possibly the study's main limitation. Despite being intrinsic to the innovative design, its impact could be reduced by diminishing the amount of methodological experimentation in future similar designs.
Finally, the possibility of open sourcing all the non-confidential coding of the platform and surveys might have increased engagement and even contributed to the automatisation of time-consuming processes. Our experience convinced us that when tools were provided to the study participants, everyone benefited after finishing the data collection period (92).
The primary limitations and the potential policy implications of this study will be briefly discussed before wrapping up this discussion.
First, this study adds to the mounting evidence that positions drug checking services as a necessary intervention to complete the monitoring of the NPS markets. Multiple occasions have proven that agile monitoring, evaluating, and understanding of constantly evolving synthetic drugs markets has delivered successful outcomes (UNODC, 2021b).
Second, these results also support the feasibility, efficacy, and ethical responsibility of involving the diverse people who use drugs in the scientific process (74). Sadly, the best practice guidelines from the Early Warning Advisory on NPS from the UNODC and the European drug prevention quality standards both do not include people who use drugs in the critical aspects of designing or evaluating interventions, despite advocating for networking with all relevant stakeholders (81, 93).
Third, provide better and faster evidence to support science-based policies instead of morals. Both quality of the information and the information gaps will affect the level of uncertainty in the answers to the questions posed. Uncertainty needs to be made explicit in the conclusions of the risk assessment to deal with the limitations of information scientifically (94).