NEW YORK (Reuters Health)—Low-dose amitriptyline does not have clear benefits for patients with chronic low-back pain that has no specific cause, according to results from a randomized clinical trial.
Despite the lack of evidence that antidepressants are more effective than placebo for low-back pain, seven of 14 national and international guidelines recommend their use in this setting.
Dr. Donna M. Urquhart from Monash University in Melbourne, Australia, and colleagues investigated whether low-dose amitriptyline (25 mg per day) is effective in reducing pain, disability and work absence and hindrance over six months in 146 patients with chronic, nonspecific low-back pain, compared with benztropine, which mimics the adverse events of amitriptyline but has no known effect on chronic pain.
At baseline, participants had a mean pain score of 41.6/100 and a mean disability score of 7.9/23. A quarter of patients reported work absence and 85% reported hindrance owing to low-back pain, the researchers report in JAMA Internal Medicine, online October 1.
Pain intensity declined by a mean 12.6 points in the amitriptyline group and by a mean 4.8 points in the benztropine group at six months. Both differences were well below the minimal clinically important difference (MCID) of 15 points, and the difference between the groups was not statistically significant.
Disability scores improved to a significantly greater extent in the amitriptyline group at three months, but the three-point improvement barely achieved the MCID, and improvements at six months did not differ between the groups.
At six months, the groups did not differ significantly in work absence, hindrance, global improvement, depression, general health, or fear of movement/reinjury.
“The most interesting result is that we found that low-dose amitriptyline tended to reduce back-related disability and pain intensity, suggesting it may be an effective treatment option for back pain,” Dr. Urquhart told Reuters Health by email.
“This is particularly important given effective treatments for back pain are limited and recent studies have shown that medications, such as paracetamol (acetaminophen), anti-inflammatories, and narcotics, don’t work,” she said.
“The cornerstone of back pain management is for patients to stay active,” Dr. Urquhart said. “However, where a patient and their doctor decide they need extra support for a short to medium period, low-dose amitriptyline may be worth considering.”
She added, “We found that prior to the commencement of the study more than 30% of participants in each group had moderate to severe symptoms that were similar to the side effects associated with low-dose amitriptyline. Given these symptoms were not a result of the study medication, they suggest that a significant proportion of the symptoms patients with low back pain report are not related to their medication use. This is important for physicians to take into consideration when they are assessing side effects thought to relate to low-dose amitriptyline.”