Our main findings are twofold. First, the TDI data show that patients starting specialist treatment for substance use problems on referral by their GP have a distinct, more favourable profile compared to patients who were referred by non-GP caregivers. They were relatively older and socially better-off considering their education, employment status and their stable housing status. They were also better off regarding substance use problems with relatively more problems of alcohol and/or pharmaceuticals, more mono-substance use and first treatment episodes. There is some evidence that problem use of alcohol alone is less severe than poly substance use or street drug use [9, 10]. Second, the SGP showed that patients starting GP treatment without receiving specialist treatment were also better off compared to similar patients receiving concurrent specialist treatment. Among the latter, fewer patients were recently employed and more had been in treatment before. We thus found evidence confirming our assumption that patients starting GP treatment and concurrently receive specialist treatment are more similar to GP-referred patients starting specialist treatment compared to patients starting GP treatment only.
This study found considerable agreement between two data sources about general practice patients with substance use problems. New knowledge was acquired about the (referred) general practice population, such as education and recent accommodation. Yet, nearly 13% of educational data were missing in the TDI.
Our study has other weaknesses. One limitation is that data were compared on an aggregated level. So far, it has been impossible to measure overlap between the two surveillance systems at the patient level by unique patient identifiers. Due to the cross-sectional design of both the studies this paper presents a mere snapshot of the populations at a given point in time. Consequently, we cannot tell whether patients started GP treatment before and/or after starting specialist treatment. Neither do we know whether patients starting specialist treatment also receive(d) GP treatment.
Yet, the essence of a treatment episode clearly differs across levels of care. As described above (see “Sample description”), the percentage of patients with more than one treatment episode was much higher in the TDI (28.7%) than in the SGP (3.5%), despite uniform definitions. Several reasons may account for this large difference. In the TDI, a treatment trajectory may include subsequent treatment episodes in different settings, e.g. hospital-based detoxification first, followed by drug-free therapy in another setting. In general practice the difference between a health problem episode and a treatment episode is relatively small, especially as to unhealthy lifestyle. Moreover, the difference between new and ongoing problems and treatment is equally blurry, especially when chronic problems are concerned. In contrast to specialist treatment, substance use may not be an issue in every GP-patient contact during a treatment episode, even when the problem is still present. Conversely, the end/start of a treatment episode is much clearer in specialist treatment: when the patient fails to show up/shows up again. Given those limitations, it is impossible to estimate the size of the gap in the TDI register due to its non-coverage of general practice.
A PubMed search (September 2019) using the medical subheadings of ‘substance-related disorders/epidemiology’ and ‘general practice’ did not reveal recent papers with comparable research questions. Papers with (comparable) findings from the EMCDDA TDI were not found in PubMed. The focus of the SGP pilot study was different but some core results are comparable, e.g. type of substance use, previous treatment episodes and regional differences . The pilot showed that seven months after the baseline recording of new and ongoing episodes of GP-treatment, 21% of the patients who continued GP treatment also received specialist treatment. This proportion is similar to the proportion of 28% episodes of concurrent specialist treatment we found in this study.
Monitoring treatment demand in general practice is one way of dealing with the problem of underdiagnosis of substance use problems, mostly alcohol, in general practice . Yet, ‘detected’ patients in general practice may have more severe problems resulting in a relatively higher rate of referrals and concurrent specialist treatment. Unfortunately, we did not find evidence to verify this assumption.
Our findings fit the knowledge about general practice and GP care of patients with chronic, recurrent substance use problems. According to a good health services model, GPs provide as much care as possible to patients and refer patients to specialist health facilities only when more complex care is needed . Continuity is a major attribute of general practice care, comprising continuing care over a lifetime, across health conditions and levels of care. In the context of substance use problems, this means preventive care, e.g. active screening and short interventions, and, aftercare or chronic patient care, e.g. patient support in case of relapse . The finding that relatively more GP-referred and GP-treated patients were using the primary substance daily in the last 30 days may be exemplary of the chronic care role of GPs towards patients with, most likely, problems of alcohol and/or pharmaceuticals. Maybe those patients seek help from their GP in times of crisis: when they are drinking too much or have relapsed into drinking. GPs may be less strict than specialist caregivers about abstinence as a condition for starting treatment, but the widespread availability of alcohol and, to a lesser degree, pharmaceuticals, possibly also play a role.
This study yielded useful information for health policy and research. We found that GPs meet the demand of a specific population with substance use problems. This population is better off in more than one way. They may prefer to seek discreet help from their GPs above having to interrupt their social/work activities and seek specialist treatment, often outside the community. In this study, a relatively small part of the TDI population was examined. We believe that further research of motivators and referring caregivers of patients starting specialist treatment for substance problems would be useful to profile the population and treatment demand.