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Table 7 Model-based* 6-month post-index all-cause total healthcare costs by index medication and DDI status and difference-in-difference comparison between pregabalin and duloxetine

From: A retrospective, matched cohort study of potential drug-drug interaction prevalence and opioid utilization in a diabetic peripheral neuropathy population initiated on pregabalin or duloxetine

  All-cause healthcare costs
  Mean 95% confidence interval
No DDI present $31,878 $9,545 - $106,461
DDI present $33,942 $8,995 - $128,076
Difference** $2,064 -
P value 0.8159 -
No DDI present $36,424 $10,847 - $122,314
DDI present $39,445 $11,904 - $130,702
Difference** $3,021 -
P value 0.4208 -
Difference-in-difference comparison $2,064 vs. $3,021  
Statistical difference† p = 0.8950
  1. *GLMM model with gamma distribution and log link. Model-based means, standard errors, and confidence intervals were derived from model and transformed into dollar values through exponentiation. All p values are calculated using Wald chi square tests through LSMEANS option. Presence of potential DDI, Drug used (duloxetine versus pregabalin), DDI*Drug interaction term, baseline demographic characteristics, baseline comorbidities present, and pre-index medication utilization controlled for in GLM model.
  2. **Represents the additional healthcare costs associated with the presence of a potential DDI.
  3. t-test, utilizing model estimates, comparing pregabalin difference (DDI minus No DDI) to duloxetine difference (DDI minus No DDI).
  4. DDI, Drug-Drug Interaction.
  5. CI, Confidence Interval.