Abstract
There are studies on the effect of low-dose amitriptyline on pain control, but there is a lack of studies on the use of amitriptyline for chronic pain and the factors associated with the prescription of traditional doses. We used a national sample cohort of patients aged ≥ 18 years who were prescribed amitriptyline along with chronic pain, without psychiatric disorders, between 2002 to 2015. We categorized the prescriptions into 2 groups according to the daily dose: low doses (≤25 mg) and traditional doses (>25 mg). Multivariable logistic regression models were used to identify factors associated with traditional dose prescriptions. Among 177,769 prescriptions for amitriptyline, 15,119 (8.5%) were prescribed for chronic pain. The prevalence of prescriptions and proportion of traditional doses of amitriptyline tended to decrease during the study period. Male sex (odds ratio [OR] 1.09, 95% confidence interval [CI] 1.05-1.13); age 65-80 years (OR 1.12, 95% CI 1.08-1.16), especially ≥ 80 years (OR 1.55, 95% CI 1.45-1.65); headaches (OR 1.18, 95% CI 1.10-1.27), receiving medical aids (OR 2.58, 95% CI 2.46-2.71); and being prescribed benzodiazepines or zolpidem concomitantly (OR 1.10, 95% CI 1.06-1.15) were significantly associated with traditional dose prescriptions of amitriptyline. Although traditional dose prescriptions of amitriptyline have been declining, close monitoring is still required in the presence of the above-mentioned factors.