Patterns of antidepressant use in people with low back pain: A retrospective study using workers' compensation data

Abstract

Background

Antidepressants are commonly used to treat low back pain (LBP), but little is known about patterns of antidepressant use in this population. This study aimed to identify patterns of antidepressant dispensing and switching in Australian workers with an accepted workers' compensation claim for LBP, and to investigate factors associated with dispensing and switching.

Methods

This retrospective study included data from accepted workers' compensation time loss claims for LBP between 2010 and 2018 with a 2-year follow-up. We described the type of antidepressant dispensed, the time for the index antidepressant to be dispensed, and whether people in the study switched to a different antidepressant. Logistic regression models investigated factors associated with antidepressants being dispensed for the first time and for switching to a different antidepressant.

Results

Antidepressants were dispensed to 2476 people with LBP (14%) at least once after a median (IQR) of 28 (10.9–54.7) weeks. Amitriptyline was the most dispensed antidepressant at any one point (47.8%), and the most common index antidepressant (42.9%). Also, 32.7% of people switched to a different antidepressant at least once. Sex, age, having been dispensed opioids, gabapentinoids or diazepam prior to antidepressants being dispensed, having used psychological services, and socioeconomic disadvantage were associated with antidepressant dispensing.

Conclusion

One in seven people with LBP were dispensed an antidepressant, most commonly amitriptyline. Antidepressants were commonly used in combination with other pain medicines such as opioids, gabapentinoids and diazepam.

Significance

Antidepressants were dispensed to one in seven people with low back pain, most commonly amitriptyline followed by duloxetine. Antidepressants were typically dispensed after 6 months and after other medicines such as opioids, gabapentinoids and diazepam had been dispensed. Due to the administrative nature of the data, the study cannot infer whether antidepressants were dispensed to treat pain or other health problems, such as a mental health condition.