The Effectiveness and Risks of Long-Term Opioid Treatment of Chronic Pain. – PubMed – NCBI – Sep 2014

I originally found this in a government-sponsored Research Review, from the Effective Health Care Program (Helping You Make Better Treatment Choices) under the Agency for Healthcare Research and Quality (AHRQ).

But now in 2019, I can’t find it there anymore. I can only find the abstract of what used to be a 219-page report, which had reached the same non-conclusion as all other studies of the last couple of decades: “more research is needed”, used when the study doesn’t find the results they wanted.

I think this increasingly common “conclusion” to studies of opioids is a pathetic evasion of the full truth.

Objectives. Chronic pain is common and use of long-term opioid therapy for chronic pain has increased dramatically. This report reviews the current evidence on effectiveness and harms of opioid therapy for chronic pain, focusing on long-term (>1 year) outcomes. Review methods. Using predefined criteria, we selected randomized trials and comparative observational studies of patients with cancer or noncancer chronic pain being considered for or prescribed long-term opioid therapy that addressed effectiveness or harms versus placebo, no opioid use, or nonopioid therapies;

different opioid dosing methods; or

risk mitigation strategies. We also included uncontrolled studies >1 year that reported rates of abuse, addiction, or misuse, and studies on the accuracy of risk prediction instruments for predicting subsequent opioid abuse or misuse. The quality of included studies was assessed, data were extracted, and results were summarized qualitatively. Results. Of the 4,209 citations identified at the title and abstract level, a total of 39 studies were included. For a number of Key Questions, we identified no studies meeting inclusion criteria. Where studies were available, the strength of evidence was rated no higher than low,due to imprecision and methodological shortcomings, with the exception of buccal or intranasal fentanyl for pain relief outcomes within 2 hours after dosing (strength of evidence: moderate). No study evaluated effects of long-term opioid therapy versus no opioid therapy. In 10 uncontrolled studies, rates of opioid abuse were 0.6 percent to 8 percent and

and rates of dependence were 3.1 percent to 26 percent in primary care settings, but studies varied in methods used to define and ascertain outcomes.

So much confusion is due to the intentionally vague definition of “dependence”.

It can apply to the physical dependence our bodies develop to many common medications, even caffeine. Or, it can be used to imply “mental dependence“, which is a hallmark of addiction.

The anti-opioid zealots have taken full advantage of this vague term, citing alarming statistics about physical dependence (which is to be expected as part of normal treatment), yet implying they apply to addiction.

The terminology of the current “opioid crisis” deliberately clouds the critically important distinction between physical “dependence” and “addiction” in order to frighten people away from all opioids.

Rates of aberrant drug-related behaviors ranged from 5.7 percent to 37.1 percent. Compared with nonuse, long-term opioid therapy was associated with increased risk of abuse (one cohort study),

overdose (one cohort study),

fracture (two observational studies),

myocardial infarction (two observational studies), and

markers of sexual dysfunction (one cross-sectional study),

with several studies showing a dose-dependent association. One randomized trial found no difference between a more liberal opioid dose escalation strategy and maintenance of current dose in pain or function, but differences between groups in daily opioid doses at the end of the trial were small. Estimates of diagnostic accuracy for the Opioid Risk Tool were extremely inconsistent and other risk assessment instruments were evaluated in only one or two studies. No study evaluated the effectiveness of risk mitigation strategies on outcomes related to overdose, addiction, abuse, or misuse. Evidence was insufficient to evaluate benefits and harms of long-term opioid therapy in high-risk patients or in other subgroups. Conclusions. Evidence on long-term opioid therapy for chronic pain is very limited but suggests an increased risk of serious harms that appears to be dose-dependent.

There is just as much “limited, but suggests…” evidence of functional pain relief as well.

It seems odd that in all these studies on opioids are looking more for abuse and addiction than pain relief, which is, after all, the only reason we take these medications.

Unfortunately, research often becomes heavily biased when undertaken in search of a certain outcome, like the far too common premise that “opiates are bad”.

More research is needed to understand long-term benefits, risk of abuse and related outcomes, and effectiveness of different opioid prescribing methods and risk mitigation strategies.

This is the very same conclusion every other review of long-term opioid use reaches.

Because pain is subjective, “imprecision and methodological shortcomings” are impossible to avoid, so it’s unlikely that definitive evidence either for or against opioid use will be found soon.

Remember: “Absence of evidence is not evidence of absence.” Just because there’s no evidence that opiates work long term doesn’t mean they don’t.