Cost-utility analysis of intravenous immunoglobulin and prednisolone for chronic inflammatory demyelinating polyradiculoneuropathy

There is a paucity of economic evidence relating to interventions for peripheral nerve disorders and the aim of this study was to illustrate the application of economic evaluation in this area by making a comparison of the cost-effectiveness of intravenous immunoglobulin and prednisolone treatment for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Patients (n=32) were recruited to a double-blind randomised cross-over trial from nine European centres and received either prednisolone or intravenous immunoglobulin during the first six-week treatment period, followed by a four-week washout period after which the other treatment was received. Service use, quality of life and physical disability were measured at baseline and at the end of both treatment periods. Cost and outcome data were available for 25 patients who completed the first arm of the study but for only 16 who completed both arms. Therefore, the focus of the economic evaluation was on the initial treatment period. Baseline costs were controlled for using a bootstrapped multiple regression model. The cost difference between the two treatments was estimated to be £1608 for the initial six week period. Physical disability fell over six weeks in both groups without any significant difference between them. Health-related quality of life, as measured by the EQ-5D, increased more in the IVIg group and this difference approached statistical significance. The incremental cost per QALY of IVIg compared to prednisolone was estimated to be £107,200. The cost per QALY is greatly affected by the price of IVIg and the amount administered. The impact of side effects on long-term costs and quality of life are likely to reduce the cost per QALY of IVIg treatment compared to prednisolone.