Tuesday, September 10, 2019

Draft USPSTF statement on screening for illicit drug use requires major revisions

It may surprise some observers that for its first quarter century, the U.S. Preventive Services Task Force did not post draft research plans, recommendation statements or systematic reviews online for public comments. Instead, these documents were developed and discussed on private conference calls and voted on at invitation-only Agency for Healthcare Research and Quality meetings, which I attended as a medical officer from 2006 through 2010. This policy changed after the media uproar over the USPSTF's 2009 mammography recommendations, which included criticism for the Task Force's lack of transparency in guideline development. Reluctant to open their meetings to the public out of fear that it would stifle candid debates about politically sensitive subjects, the USPSTF chose, instead, to institute a one-month public comment period on draft documents before finalizing their recommendations.

For the first few years, public comments resulted in few significant changes to draft statements. However, there are now examples of the public comment period leading to substantial changes in recommended testing options and letter grades in high-profile topics such as screening for colorectal cancer and cervical cancer. That's a good thing, since the USPSTF draft statement on screening for illicit drug use, which recently closed to public comments*, requires major revisions.

In 2008, the USPSTF concluded that "the current evidence is insufficient to assess the balance of benefits and harms of screening adolescents, adults, and pregnant women for illicit drug use." What specific evidence gap prevented them from making a recommendation?

The most significant research gap identified by the USPSTF is the lack of studies to determine if interventions found effective for treatment-seeking individuals with symptoms of drug misuse are equally effective when applied to asymptomatic individuals identified through screening.

Consequently, the research plan finalized by the USPSTF in October 2016 to update their 2008 statement focused on summarizing evidence of the benefits and harms of counseling interventions to reduce drug use in "screen-detected persons." Focusing the systematic review on this population recognized that their willingness and motivation to change their drug use behavior in response to an intervention likely differs from those who actively seek medical treatment.

The draft review produced by the team that carried out this research plan determined that a great deal more applicable evidence was published in the past decade: 27 randomized, controlled trials with a total of 8,705 participants. The studies' findings, however, were disappointing for advocates of screening:

Across all 27 trials, in general, there was no consistent effect of the interventions on rates of self-reported or biologically confirmed drug use at 3- to 12-month followup. Likewise, across 13 trials reporting the effects of the interventions on health, social, or legal outcomes, none of the trials found a statistically significant difference between intervention and control groups on any of these measures at 3- to 12-month followup.

In other words, interventions for persons who had illicit drug use detected by screening didn't reduce drug use, improve physical health, or lead to fewer brushes with the law. No benefit + no harm (though only 4 studies reported on potential screening harms) = no net benefit. So the appropriate response to the evidence would be to either recommend against primary care screening for illicit drug use (since it adds burden to practices without benefiting patients), or, if the studies were considered too heterogenous to make that definitive a conclusion, to declare the evidence insufficient to determine the balance of benefits and harms.

Here, though, is where the Task Force appears to have gone off the rails. Rather than draw one of these two evidence-based conclusions, they instead commissioned a second systematic review from a completely different team (without posting a new research plan for public comment) seeking evidence on interventions in treatment-seeking populations. This draft review concluded that psychosocial interventions increase the likelihood of abstinence from drug use for up to 12 months, and that there are effective medications for opioid use disorder in persons who desire treatment (nice to confirm, but hardly a novel finding). The USPSTF relied on this second review (and apparently ignored the first one) to support their draft "B" recommendation to screen for illicit drug use in adults age 18 years or older.

Don't primary care clinicians already ask their patients about illicit drug use? We certainly do, as part of taking the social history of a new patient, but not in the methodical, intensive way that the USPSTF is now recommending. Perhaps the Task Force felt compelled by the pressure of the opioid epidemic to offer something more in terms of clinical prevention than an "I" statement or a politically unpalatable "D" recommendation against screening. Regardless of their rationale, by bypassing their published methods and processes to produce a statement that the evidence clearly doesn't yet support, the USPSTF has ventured onto dangerous ground, raising questions about their scientific credibility at a time when evidence-based institutions need to be defended more than ever.


* - A summary of my assertions in this post was submitted to the USPSTF during the public comment process.