US long-term use of muscle relaxants has skyrocketed since 2005

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US doctor visits for ongoing prescribing of skeletal muscle relaxant drugs tripled from 2005 to 2016, according to a study from researchers in the Perelman School of Medicine at the University of Pennsylvania. Moreover, in 2016, nearly 70% of patients prescribed muscle relaxants were simultaneously prescribed an opioid – a combination that has the potential to cause dangerous interactions. The researchers also found that muscle relaxants were prescribed disproportionately to older adults during this time period, despite national guidelines warning that this class of drugs should almost always be avoided in patients who are 65 and older.

“There are few studies on the short-term efficacy and safety of skeletal muscle relaxants, and almost no data on their long-term effects, so it is very concerning that patients, and particularly older adults, are using these drugs for an extended period of time,” said Dr Charles E Leonard, an assistant professor of epidemiology. “Providers seem to be reaching for them despite incomplete information on their potential benefits and risks.”

Skeletal muscle relaxants are drugs that were approved years ago for short-term treatment of muscle spasms and back pain, and are used today, without good evidence, to treat chronic pain and other conditions. Recommendations generally limit the use of these drugs to a maximum of three weeks, since they have not been shown to work for muscle spasms beyond that duration, and they can cause serious side effects including falls, fractures, vehicle crashes, abuse, dependence, and overdose. Due to these risks, muscle relaxants should be avoided altogether in elderly patients, according to guidelines from the American Geriatrics Society.

Despite these concerns, Leonard and his colleagues hypothesised that the growing opioid epidemic may have led clinicians to prescribe muscle relaxants as an alternative to opioids for long-term pain management.

To measure national trends in muscle relaxant prescribing, the researchers analysed publicly-available 2005-2016 data from the National Ambulatory Medical Care Survey. NAMCS is a US-based annual survey of non-federally funded office-based physicians engaged in direct patient care. The researchers examined the total number of visits per year, and stratified counts by the muscle relaxant agent, whether the drug was newly prescribed or continued therapy, as well as the race, ethnicity, and sex of the patient, and the region of the visit.

From 2005 to 2016, the number of office visits resulting in new muscle relaxant prescriptions remained stable at approximately 6m per year, while office visits for continued muscle relaxant drug therapy tripled – from 8.5m in 2005 to 24.7m in 2016. Worryingly, older adults accounted for 22.2% of all muscle relaxant visits in 2016, even though this group accounted for just 14.5% of the US population. Also of concern, in 2016, 67% of the continued muscle relaxant visits also recorded therapy with an opioid.

The US Food and Drug Administration warns against use of co-prescribing of these medications, because of the risk of serious side effects, including slowed or difficult breathing, and death.

“For older adults, I think the message should be to avoid using muscle relaxants, especially when we consider the side effects and increased risk of falls and fractures, and to find alternatives for pain management,” said the study’s first author Dr Samantha Soprano, a research coordinator and student in Penn’s Master of Behavioural and Decision Sciences programme.

Leonard added that, in addition to potential adverse effects, muscle relaxants may not be any more effective in managing pain than medications like Tylenol or Advil. Past studies examining muscle relaxants found they were more efficacious than a placebo, but they were not compared to other therapies. Further research is needed to determine more detailed information about the effects of muscle relaxants, particularly when used for longer periods of time, since their use is so widespread, Leonard said. Additionally, doctors need better, safer options for managing patients’ pain.

“Muscle relaxants’ place in therapy is really limited. Based on most guidelines, they’re normally reserved as second- or third-line therapies,” Leonard said. “Our findings suggest that prescribers may be reaching for these drugs sooner than that.”

This research was supported by funding from the National Institutes of Health.

Importance: Little is known to date about national trends in the prescribing of skeletal muscle relaxants (SMRs), the use of which is associated with important safety concerns, especially in older adults and in those who use concomitant opioids.
Objective: To measure national trends in SMR prescribing over a 12-year period.
Design, Setting, and Participants: This cross-sectional study used data from the National Ambulatory Medical Care Survey from January 2005 to December 2016. Data were analyzed from August 21, 2018, to July 18, 2019. The study included patients with ambulatory care visits who had encounters with non–federally funded, office-based physicians in the United States.
Exposures: SMR use, categorized as newly prescribed or continued therapy at the office visit.
Main Outcomes and Measures: Ambulatory care visits—overall and stratified by calendar year, geographic region, and patient age, sex, and race—in which an SMR was newly prescribed or continued were quantified. Among office visits in which an SMR was newly prescribed, diagnoses were assessed. Concomitant medications were quantified for all office visits, stratified by new or continued therapy. Survey visit weights were used to estimate nationally representative measures, and age-standardized rates were generated by geographic region using US Census data.
Results: This study included a total of 314 970 308 office visits (mean [SD] age, 53.5 [15.2] years; 194 621 102 [61.8%] men and 120 349 206 [38.2%] women). In 2016, there were 30 730 262 (95% CI, 30 626 464-30 834 060) US ambulatory care visits in which an SMR was either newly prescribed or continued as ongoing therapy. Patients in these visits were most frequently female (58.2% [95% CI, 57.9%-58.6%]), white (53.7% [95% CI, 53.4%-54.0%]), and aged 45 to 64 years (48.5% [95% CI, 48.2%-48.9%]). During the study period, office visits with a prescribed SMR nearly doubled from 15.5 million (95% CI, 15.4-15.6 million) in 2005 to 30.7 million (95% CI, 30.6-30.8 million) in 2016. Although visits for new SMR prescriptions remained stable, office visits with continued SMR drug therapy tripled from 8.5 million (95% CI, 8.4-8.5 million) visits in 2005 to 24.7 million (95% CI, 24.6-24.8 million) visits in 2016. Older adults accounted for 22.2% (95% CI, 21.8%-22.6%) of visits with an SMR prescription. Concomitant use of an opioid was recorded in 67.2% (95% CI, 62.0%-72.5%) of all visits with a continuing SMR prescription.
Conclusions and Relevance: This study found that SMR use increased rapidly between 2005 and 2016, which is a concern given the prominent adverse effects and limited long-term efficacy data associated with their use. These findings suggest that approaches are needed to limit the long-term use of SMRs, especially in older adults, similar to approaches to limit long-term use of opioids and benzodiazepines.

Samantha E Soprano, Sean Hennessy, Warren B Bilker, Charles E Leonard


University of Pennsylvania School of Medicine material


JAMA Network Open abstract

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