A Survey of Intravenous Immune Globulin (IVIG) Dosing Strategies

Intravenous immune globulins (IVIGs) are used at various doses for a wide variety of labeled indications and off-label uses. Official labeling and commonly used general references list mg/kg doses, but fail to specify the patient weight that should be used in calculating each dose. One could infer that mg/kg dosing should be based on actual or total body weight because no qualifiers like “ideal [lean] body weight” or “adjusted body weight” are used in references. Furthermore, references do not list doses for special populations, such as obese patients. Based on the distribution of IVIGs in the body, which is similar to normal plasma, some have argued that ideal or an adjusted body weight between actual and ideal body weight may be used for dosing. Lower doses may preserve scarce resources, minimize cost, and decrease the risk of adverse reactions. The use of ideal body weight dosing has been shown to reduce IVIG use by 20%. However, some have questioned whether there is sufficient evidence to use ideal or adjusted body weight to dose IVIGs. Further inconsistencies in IVIG dosing may arise from dose-rounding practices, which have been described for other expensive intravenous drugs. Dose rounding, along with the use of varying dosing weights could result in considerable differences in the amounts of IVIG used to treat patients, especially in obese patients. Therefore, we conducted a cross-sectional survey to determine the prevalence of different dosing and dose-rounding strategies for IVIGs used at academic medical centers.