Variations and determinants of novel psychoactive substance use: a mixed methods study to identify the implications for policy and practice

Background -The public health impact of increasingly dynamic and complex drug scenes (EMCDDA 2017, UNDOC 2017) remain of global concern. ‘New psycho-actives’ (NPS) are a contributor to this changing polydrug use vista. Knowledge of multiple substance use and analysis of overlaps between different drug using populations, especially with regard to NPS is limited with theoretical and empirical evidence persistently falling behind the adoption of consumption practices. This paper reports on a mixed method study (funded by NIHR) providing new empirical public health-related research evidence on novel psychoactive substances (NPS).

The session will be structured around methods, results and consideration of the findings of this study.

Methods -The study leveraged data from the Belfast Youth Development Study (BYDS), an eighteen-year longitudinal cohort study (see Higgins et al. 2019) to create a three-phase mixed methods design with a shared conceptual framework, based on risk and protective factors within individual, family and community contexts. Phase 1: (Quantitative) secondary analysis of the BYDS - latent class analysis using 2,039 BYDS participants. Phase 2: (Qualitative) extensive qualitative analysis via narrative interviews of participants, sampled from BYDS, drug and alcohol service settings and the prison estate (n=84), to explore highly detailed substance use repertoires and location of NPS therein, e.g. patterns of use, primary motivations for substances used, risks and harms from use. Phase 3: (Quantitative) The generalisability of the shared risk factor part of the model was tested using a three-Step Approach manual method to examine risk factors associated with latent class membership. Several integration analyses were built into the design to maximise the utility of the sequential mixed-methods.

Results

• Identifying where NPS use sits within substance use classes (LCA):

Analyses suggested that amongst our sample there was not a distinctive ‘NPS class’. Rather, the LCA identified 4 broad types of substance use within our sample: alcohol, tobacco and cannabis (ATC, n=367; 18%), alcohol and tobacco (AT; n=926; 45%), alcohol (n= 532; 26%) and polydrug use (n=214; 10%). Classes were named according to the substances for which the probability of previous use was 50% or above. For the polydrug class the LCA revealed probability at or above 50% for previous use of alcohol, tobacco, cannabis, ecstasy, speed, cocaine, poppers and NPS, and below 50% for all other substances. The results revealed that while there is no unique ‘NPS class’, NPS use is a feature of broader polydrug use. In fact, amongst polydrug users in our sample, 71% reported previous NPS use.

• Construction of a Taxonomy of NPS use

The narratives provided dynamic data on the life cycle of participants’ use. A taxonomy of NPS use was constructed using key conceptual fields (e.g. broad risk and protective factors for substance use, substance use repertoires, patterns of all drug and alcohol use, primary motivations for use, effects, drivers for switching between substances, critical incidents, harms, dependence. This 4 group (and sub-group) categorisation was used to explain how use on NPS was conceived of in a ‘limited experimental way’ or a ‘dependent way’ and what differentiated groups from one another. ‘Generation NPS’ in Group 4 were the closest to a NPS only category moving from use of alcohol through to dependence on synthetic cannabinoids.

Group 1 Limited Experimentals

Group 2 Past Recreationals

Group 3 Contemporary Regulars

Group 4 Dependents (includes 4 sub-groups)

• Focus on Synthetic Cannabinoids

Synthetic Cannabinoids (SC’s) use was either very experimental and generally an isolated incident, or use was reported as characteristic of dependence. Participants had little awareness of the risks associated with SCs. This was evident across both highly experienced and less experienced user groups. This was predicated on an assumption that SCs were akin to cannabis. Use of SCs provided a transition back onto heroin; less experienced users reflected on SCs’ role in providing an accelerated pathway to heroin use.

• Key risk and protective factors for substance use

Variables were carefully selected from the BYDS dataset to align as closely as possible with the risk and protective factors related to substance use that emerged from the qualitative analysis. The selected BYDS risk and protective factors variables were entered into the model. Notably, very little distinguished the ATC and polydrug groups.

• Adult outcomes associated substance use

All outcome models controlled for gender, socio-economic status and the early and protective factors associated with substance use. Compared to polydrug users the AT group were less likely to have poor outcomes in adulthood in most of the areas examined. Only in a few areas were ATC users less likely to have poorer outcomes than polydrug users; specifically, drug use, cannabis use and offending.

• Suggested Interventions/Treatment Modalities Mapped onto our Empirical Findings

In constructing our taxonomy, we located various types of NPS use within a range of polydrug trajectories. A consideration of results, categorised according to each of the four groupings, raise a number of important issues for policy and practice. We provide suggested intervention and treatment modalities, building on Project Neptune.