Prescription Patterns in Patients with Incident Trigeminal Neuralgia

Background: Trigeminal neuralgia (TN) is a rare neuropathic pain disorder that occurs mostly in older adults and has the potential of significantly affect health-related quality of life. Although carbamazepine is currently the only FDA-approved medication to treat TN, clinical guidelines recommend gabapentinoids (gabapentin and pregabalin) only as second-line therapy. Given the overall increased use of gabapentinoids in recent years in the United States and their questionable effectiveness in certain neuropathic pain conditions, there is need to understand drug utilization patterns for TN.

Objectives: We aimed to examine the drug utilization trends in the use of pharmacological treatments in patients newly diagnosed with TN.

Methods: We conducted a retrospective repeated cross-sectional study using IBM® MarketScan® Research Databases from 2005 to 2019. We examined the annual prevalence and average annual percent change (AAPC) of use of carbamazepine, oxcarbazepine, gabapentin, pregabalin, opioids, baclofen, duloxetine, lamotrigine and topiramate among patients with newly diagnosed TN who received any pharmacotherapy. Patients were considered exposed if there was a dispensing record within 7 days prior or 30 days after TN diagnosis. TN was identified using ICD-9-CM/ICD-10-CM diagnosis codes and individuals were required to have at least two medical claims for TN on two separate dates, 14 days or more apart.

Results: We identified 6,091 patients with incident diagnosis of TN. Of them, 74.34% were women and the mean age (SD) was 49.52 (10.92) years. Gabapentin was the most common drug used to treat incident TN, with increasing utilization prevalence during the study period (AAPC = 7.8% [95%CI: 2.5%,13.3%]). Carbamazepine (AAPC = 0.93% [95%CI: -0.5%, 2.4%]) and oxcarbazepine (AAPC = 1.79% [95%CI: 0.2%, 3.4%]) were the second and third most prescribed medications, respectively. Although prescription of opioids decreased from 21.6% in 2006 to 5.4% in 2018, 8.4% of patients with TN were initiated on opioids in 2019.

Conclusions: Gabapentin has been increasingly used as first-line therapy to treat TN at incident diagnosis despite clinical recommendations of restricting their use to patients who do not tolerate carbamazepine nor oxcarbazepine. Although the use of opioids decreased over the study period, they were still commonly used despite lack of evidence of their effectiveness to treat TN.