Study design: Population-based cross-sectional prevalence survey.
Objectives: To define muscle relaxant use patterns in the United States.
Summary of background data: Despite a long history of use for back pain and musculoskeletal disorders, national prevalence patterns of prescription muscle relaxant use have not been defined.
Methods: NHANES III (1988-1994) is an in-person health examination survey of the U.S. civilian population, based on a complex, multistage probability sample design.
Results: An estimated 2 million American adults reported muscle relaxant use (1-month period prevalence 1.0%; 95% confidence interval 0.8-1.3%). While virtually all (94%) used individual muscle relaxants rather than fixed combination muscle relaxant analgesics, two thirds took an additional prescription analgesic. Men and women had similar usage. Median user age was 42 years, but 16% of users were older than 60 years. Eighty-five percent of users took muscle relaxants for back pain or muscle disorders. Two thirds of muscle relaxant users had histories of recent back pain; however, only 4% of all those with a recent history of back pain reported any muscle relaxant use. Mean length of use was 2.1 years (95% confidence interval 1.6-2.6), with 44.5% taking medication longer than a year (95% confidence interval 35.7-53.3). Muscle relaxant use in the elderly, among older persons with ambulatory impairments, and in chronic obstructive pulmonary disease appeared undiminished compared with general population use.
Conclusions: Although typically recommended for short-term treatment of back pain, muscle relaxants are often used chronically and are prescribed to subpopulations potentially at risk for adverse effects.