The Gates et al.  randomized controlled trial (RCT) found that an efficacious face-to-face treatment combining motivational interviewing (MI) and cognitive–behavioral therapy (CBT) for cannabis users could be delivered by telephone with only modest decrements in benefits. The study thus extended to cannabis-related problems the widespread support for MI and CBT found for other addictive and health behavior problems [2, 3], and demonstrated that benefits were maintained using a delivery channel other than the in-person therapeutic dyad. Another contribution was the finding that changes in abstinence self-efficacy partially mediated intervention outcomes .
These are welcome, incremental additions to evidence for MI–CBT efficacy across target behaviors, delivery channels, formats, providers and settings [3, 4]. However, the results must be qualified by procedural shortcomings inconsistent with RCT best practices (e.g. brief follow-up, non-trivial attrition, author-conducted fidelity and outcome assessments; considerable extra-therapeutic treatment-seeking).
The authors made strong claims, despite these limitations, that their intervention is ‘novel’; has potential to reduce the ‘public health burden attributable to cannabis use to a greater extent than a face-to-face service’; and may appeal to people who ‘prefer [intervention] anonymity’. They are correct that a population perspective supports a spectrum of substance-related services that ranges from clinical treatment to accessible, low-intensity interventions  and makes use of both clinical and public health tools . However, their telephone-based intervention was not as distinct from conventional treatment as the authors suggest, and it thus advanced public health goals only modestly.
First, like typical RCTs of clinical treatments, the majority of interested respondents were excluded, and the minority enrolled were seeking, although not receiving, professional treatment for cannabis use, and 35% were taking ‘withdrawal medication’. During the 12-week follow-up, more than 25% were taking medication, receiving other treatment or both (per Table 1 in the original paper). Even with statistical controls, this extra-therapeutic help-seeking coupled with recruitment of a counseling-seeking sample meant that non-treatment-seekers were not included. Thus, the study did little to advance care for the untreated majority of cannabis users.
Secondly, the intervention was not brief, low-intensity or low-threshold, desirable features for reaching more people with problems, nor was it anonymous. As with accessing clinical services, acceptance into the study and access to MI–CBT treatment presented a high threshold. Like a clinical intake, the initial interview assessed in detail cannabis use, related problems and dependence levels; stage of change; self-efficacy (confidence) to reduce cannabis use or abstain; and other drug use. Then, participants either were wait-listed for services delayed for 12 weeks, a frequent occurrence in real-world treatment systems, or received up to four 1-hour weekly counseling sessions. Sessions were accompanied by homework and follow-up calls at 4 and 12 weeks. This has all the usual characteristics of clinical care, save that treatment was delivered by telephone. This change addresses geography as a treatment barrier, but does not reduce other barriers (e.g. inconvenience, stigma) or expand the reach and impact of care by providing accessible user-friendly services when cannabis users’ motivations shift away from drug use towards positive change.
Thirdly, the intervention did not optimize the use of telephone technology to reach large segments of the at-need population with relatively efficacious and somewhat individualized interventions [6, 7]. A basic tenet of public health practice is that more efficacious clinical interventions on a per-person basis may have a lower overall population impact than less efficacious public health interventions that reach many more people. An emerging strategy is to integrate public health and clinical approaches to target larger risk groups with semi-individualized interventions using telephone- and computer-delivered applications guided by behavior change theory .
Examples include service delivery via Interactive Voice Response (IVR) telephone platforms that can be made available continuously for long intervals to monitor and support behavior change, aid relapse prevention and promote needed stepped care [8-10]. IVR interventions have been used as a clinical treatment adjunct , for aftercare  and to support change in otherwise untreated substance misusers . Other cellphone voice and text applications have involved frequent, real-time, brief therapeutic messages variously designed to improve treatment adherence, promote healthy behaviors and guide coping in high-risk situations [6, 11]. Growing smartphone adoption means that previously developed computer programs that used behavior theory to match change materials to individual needs, resources and readiness to change will have unprecedented portability and reach [12, 13].
An optimal continuum of care for drug problems will support consumer-selected and professionally recommended choices across a range of services in ways that maximize individual and aggregate benefits . The Gates et al.  intervention fills a narrow niche along the continuum, far closer to in-person clinical care for motivated treatment-seekers than to public health or integrated options for the under-treated majority that may benefit from less intensive interventions.
Declaration of interests