Switching Topical Diclofenac from Higher to Lower Strength: Financial and Clinical Evaluation

In February 2020, the Fraser Health Authority in British Columbia introduced an automatic therapeutic interchange policy, whereby orders for any strength of topical diclofenac would be automatically interchanged to the commercially available diclofenac 2.32% gel for twice-daily administration. The new policy was intended mainly as a cost-saving measure but had the potential for clinical impacts that needed to be considered.

To evaluate the financial and clinical impact of the automatic therapeutic interchange policy for topical diclofenac.

A financial evaluation and a clinical evaluation were conducted. Expenditures for topical diclofenac before and after implementation of the automatic therapeutic interchange policy were compared. To obtain information about the clinical impact of the interchange, a retrospective chart review was conducted at long-term care sites. The primary outcome was a composite of 7 components that could indicate worsening of pain in 3 prespecified scenarios.

The financial evaluation showed that the interchange could potentially save the health authority more than $200 000 over 12 months. The clinical evaluation showed that 25%-48% of patients met the primary outcome of worsening pain (analyzed according to 3 different scenarios) after the switch to lower-strength diclofenac, with increases in use of as-needed topical diclofenac and other analgesics being the main indicators of worsening pain.

An automatic therapeutic interchange policy that switched orders for higher strengths of diclofenac to the 2.32% concentration resulted in large financial savings and, in most cases (52%-75% of patients), did not appear to affect pain control. Prospective studies comparing the clinical impact of higher- and lower-strength topical diclofenac products are warranted.