Erratum to Cost utility of tumour necrosis factor-α inhibitors for rheumatoid arthritis: an application of Bayesian methods for evidence synthesis in a Markov model

Abstract

The authors have reported a number of corrections to their analysis following the Letter to the Editor by Diamantopoulos et al. [1] These corrections have not affected the conclusions of the article but have resulted in a number of changes to the cost and utility results presented throughout the text, figures and tables. In addition, a wider range of utility values were tested in the one-way sensitivity analyses as the corrections resulted in a wider variance than previously reported. Please refer to Bounthavong et al.'s reply [2] to Diamantopoulos et al. for a more comprehensive explanation of these errors and to the online corrected version for correct cost and utility results.

Validity of Cost and Utility Results?

“…We read with interest the research conducted by Nguyen and colleagues [1] to identify the costeffective agent for treatment of moderately to severely active rheumatoid arthritis (RA) from the US healthcare payer's perspective.…”

“…The model time horizon is set to 5 years; however, the estimated utility exceeds 5 QALYs and is over 10 QALYs for some of the strategies (table V). [1] Can the authors clarify how this calculation was made?…”

“…Furthermore, the acquisition cost of methotrexate (MTX) per cycle is 5% of that for etanercept (table III). [1] In addition the cost of a non-responder (which includes acquisition and administration costs of tocilizumab and extra physician visits) is still lower than that of the cost of etanercept. Can the authors clarify the difference in the total cost of MTX and etanercept strategies (Delta$ US5000 in table V), [1] given that MTX and 'nonresponders' cost less?…”

“…We understand from the paper that serious infection costs are also included in the above estimates for the total strategy costs. However, the incidence of serious infections is reported to be similar for both comparators: MTX and etanercept (~3.5%) [table S3 in the Supplemental Digital Content], [1] and therefore it is unclear how this could account for the difference in costs between the two strategies. Furthermore, is this similarity in the safety profile of the two agents plausible considering MTX is an oral therapy?…”

“…We thank Diamantopoulos and colleagues [1] for taking an active interest in our study [2] and for their careful examination of our work. As with any simulation, there are inherent limitations; however, the comments and observations by Diamantopoulos et al [1] have identified a specific error in the QALY calculations.…”