Comparison of the flexible parametric survival model and Cox model in estimating Markov transition probabilities using real-world data

Abstract Background and Aims We evaluated the cost-effectiveness of early [≤2 years after diagnosis] compared with late or no biologic initiation [starting biologics >2 years after diagnosis or no biologic use] for adults with Crohn’s disease in Switzerland. Methods We developed a Markov cohort model over the patient’s lifetime, from the health system and societal perspectives. Transition probabilities, quality of life, and costs were estimated using real-world data. Propensity score matching was used to ensure comparability between patients in the early [intervention] and late/no [comparator] biologic initiation strategies. The incremental cost-effectiveness ratio [ICER] per quality-adjusted life year [QALY] gained is reported in Swiss francs [CHF]. Sensitivity and scenario analyses were performed. Results Total costs and QALYs were higher for the intervention [CHF384 607; 16.84 QALYs] compared with the comparator [CHF340 800; 16.75 QALYs] strategy, resulting in high ICERs [health system: CHF887 450 per QALY; societal: CHF449 130 per QALY]. In probabilistic sensitivity analysis, assuming a threshold of CHF100 000 per QALY, the probability that the intervention strategy was cost-effective was 0.1 and 0.25 from the health system and societal perspectives, respectively. In addition, ICERs improved when we assumed a 30% reduction in biologic prices [health system: CHF134 502 per QALY; societal: intervention dominant]. Conclusions Early biologic use was not cost-effective, considering a threshold of CHF100 000 per QALY compared with late/no biologic use. However, early identification of patients likely to need biologics and future drug price reductions through increased availability of biosimilars may improve the cost-effectiveness of an early treatment approach.

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Overall survival of cetuximab administered every two weeks versus weekly in real-world data of U.S. patients with metastatic colorectal cancer.

Journal of Clinical Oncology ◽

10.1200/jco.2020.38.4_suppl.23 ◽

2020 ◽

Vol 38 (4_suppl) ◽

pp. 23-23 ◽

Cited By ~ 1

Author(s):

Chris Pescott ◽

Michael Batech ◽

Emmanuelle Boutmy ◽

Philippe Ronga ◽

Francois-Xavier Lamy

Keyword(s):

Colorectal Cancer ◽

Overall Survival ◽

Metastatic Colorectal Cancer ◽

Real World ◽

Cox Model ◽

Small Sample Size ◽

Small Sample ◽

Patient Death ◽

Real World Data ◽

World Data

23 Background: Cetuximab (CET) administered weekly (q1w) at 250 mg/m², after an initial dose of 400 mg/m², is approved in combination with chemotherapy (CT) for the treatment of (K) RAS wild-type metastatic colorectal cancer (mCRC). The use of CET 500 mg/m2 administered with CT every 2 weeks (q2w) is according to US clinical practice guidelines and observed routinely. In this study, we compared q2w vs q1w regimens on overall survival (OS) in a presumed first-line (1L) treatment subcohort and present updated data on the noninferiority of q2w vs q1w in line-agnostic (1L+) treatment using US real-world data. Methods: Using IBM MarketScan, a large US insurance claims database, we classified a cohort of mCRC patients treated between 07/2010 and 12/2016 with CET+CT as q1w or q2w based on observed infusion patterns. Absence of mCRC-related treatment claims preceding CET initiation date (defined as the index date) qualified as CET treated in 1L. A validated algorithm was used to determine patient death. Confounding was accounted for using high-dimensional propensity scoring (hdPS) with inverse probability of treatment weights. OS was compared using Cox proportional hazards regression. Imbalanced confounders after hdPS were added to the Cox model. In 1L+, noninferiority of the q2w regimen was tested with a margin hazard ratio (HR) of 1.25. However, noninferiority could not be tested in 1L due to the small sample size; a test for difference was used instead. Results: Of 2,730 CET-exposed mCRC patients (updated), 1,779 (65.2%) and 951 (34.8%) were classified in q1w and q2w groups, respectively, among which 557 (31.3%) and 316 (33.2%) received CET in 1L. The HR (95% CI) for OS of q2w vs q1w in 1L was 1.10 (0.92-1.31; crude), and 1.05 (0.86-1.29; adjusted; p for difference: 0.625). In 1L+, crude and adjusted HRs were 1.05 (0.94-1.18) and 0.94 (0.85-1.03), respectively, rejecting the inferiority hypothesis at p < 0.001. Conclusions: Only a third of patients received CET in 1L in this study. OS was statistically noninferior in q2w vs q1w in 1L+, and adjusted results in 1L suggest no differences between both treatment schedules. However, more data would be needed to formally test the noninferiority hypothesis in 1L.

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