(B-001) Impact of gabapentinoids use on healthcare utilization and expenditure among female breast cancer survivors in the United States: A propensity-score matched cohort study

Background: Gabapentinoids are widely used for off-label indications, such as cancer pain. However, their impact on healthcare utilization and expenditures among breast cancer survivors, who experience a high prevalence of pain, remains unclear.

Objectives: To assess effects of gabapentinoids versus duloxetine on healthcare utilization and expenditures among U.S. female breast cancer survivors.

Methods: A propensity-score matched cohort study was conducted using U.S. Merative MarketScan® claims data (2014-2022). Female breast cancer survivors aged ≥18 years old with one-year continuous health insurance coverage were included. Exposures were new initiation of a gabapentinoid or active comparator duloxetine (Group 1: gabapentin vs. duloxetine; Group 2: pregabalin vs. duloxetine). Each group was matched based on propensity scores to minimize bias, conditional on predefined covariates (e.g., socio-demographics, baseline healthcare utilization and expenditures, breast cancer stage and treatments, opioid dosage, comorbidities, and co-medications). Primary outcomes included healthcare utilization and expenditures across inpatient, emergency department, outpatient, and outpatient prescription claims over one-year of follow-up. Zero-inflated negative binomial regression and two-part models were used to estimate differences in mean (standard deviation) and incidence rate ratio (IRR).

Results: Of 42,511 eligible breast cancer survivors, 5,036 (11.8%) matched pairs were identified in Group 1 and 2,879 (6.8%) in Group 2. Gabapentinoids versus duloxetine was associated with a 6%-7% increase in outpatient visits (Group 1: 37 (27) vs. 35 (26), IRR 1.06 (1.02-1.11), p=0.003; Group 2: 40 (28) vs. 37 (26), IRR 1.07 (1.02-1.13), p=0.009). No differences in other healthcare utilization were observed between either gabapentinoid and duloxetine. Gabapentin versus duloxetine was associated with a 15% increase in costs for outpatient visits (Group 1: $10,908 ($25,963) vs. $9,428 ($20,401), IRR 1.15 (1.06-1.26), p=0.002). Outpatient costs did not differ between pregabalin and duloxetine (Group 2: $11,278 ($22,166) vs. $10,575 ($21,943), IRR 1.06 (0.96-1.18), p=0.258). Gabapentinoid use did not affect other healthcare expenditures compared to duloxetine.

Conclusions: Gabapentinoids were associated with a slight increase in number of outpatient visits compared to duloxetine among U.S. female breast cancer survivors, with higher outpatient costs observed for gabapentin use. These results may reflect increased resource use and pain management needs in oncology care during outpatient visits. Further research is needed to assess the impact of gabapentinoid use in other cancer types and conditions.