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Table 2 Dose escalation and IPTW-adjusted Medicare-approved amount for the biologic medication through week 78, in both the as-observed and persistent cohorts

From: Will savings from biosimilars offset increased costs related to dose escalation? A comparison of infliximab and golimumab for rheumatoid arthritis

 Infliximab (N = 5174)Golimumab (N = 2843)p value
Overall cohort
 Dose escalation*, %49.464.89< 0.0001
  Dose increase, %39.493.17< 0.0001
  Frequency increase, %29.151.79< 0.0001
 Discontinuation, %73.3379.85< 0.0001
 Biologic Medicare-approved amounts, day 0–546, $
  All biologics**
   LS mean (95% CI)26,934 (26,441–27,435)35,512 (34,849–36,187)< 0.0001
  Index biologic
   LS mean (95% CI)21,216 (20,737–21,706)28,146 (27,497–28,810)< 0.0001
 Biologic Medicare-approved amounts, day 183–546, $
  All biologics**
   LS mean (95% CI)16,401 (15,699–17,135)20,512 (19,615–21,450)< 0.0001
  Index biologic
   LS mean (95% CI)11,488 (10,813–12,205)14,055 (13,213–14,951)< 0.0001
Persistent cohort (no switch or gap > 10 weeks)N = 1380N = 573 
 Dose escalation*, %71.967.85< 0.0001
  Dose increase, %58.555.24< 0.0001
  Frequency increase, %45.002.97< 0.0001
 Biologic Medicare-approved amounts, day 0–546, $
  Index biologic
   LS mean (95% CI)34,671 (33,891–35,470)43,940 (42,849–45,058)< 0.0001
 Biologic Medicare-approved amounts, day 183–546, $
  Index biologic
   LS mean (95% CI)22,877 (22,301–23,467)27,454 (26,692–28,238)< 0.0001
  1. LS inverse probability treatment (IPTW)-weighted least square mean
  2. IPTW weighting controlled for patient age, sex, race, number of physician visits, number of prior biologic DMARDS, methotrexate use, statin use, reason for eligible for Medicare, and 55 of the CCS categories (Additional file 1: Table S2) which were significant in univariate analyses in their association with cost from day 183–546
  3. *Dose and frequency increases are not mutually exclusive. Note that two consecutive infusions were required to meet definition for dose and frequency escalation
  4. **Includes cost of both the index therapy (infliximab or golimumab) and any subsequent biologic switch through day 546. Costs from day 183–546 were shown to be able to describe costs following the loading period for each drug