Cost-Savings Analysis of Renal Scintigraphy, Stratified by Renal Function Thresholds: Mercaptoacetyltriglycine Versus Diethylene Triamine Penta-Acetic Acid

Abstract

PurposeTo determine the financial implications of switching technetium (Tc)-99m mercaptoacetyltriglycine (MAG-3) to Tc-99m diethylene triamine penta-acetic acid (DTPA) at certain renal function thresholds before renal scintigraphy. MethodsInstitutional review board approval was obtained, and informed consent was waived for this HIPAA-compliant, retrospective, cohort study. Consecutive adult subjects (27 inpatients; 124 outpatients) who underwent MAG-3 renal scintigraphy, in the period from July 1, 2012 to June 30, 2013, were stratified retrospectively by hypothetical serum creatinine and estimated glomerular filtration rate (eGFR) thresholds, based on pre-procedure renal function. Thresholds were used to estimate the financial effects of using MAG-3 when renal function was at or worse than a given cutoff value, and DTPA otherwise. Cost analysis was performed with consideration of raw material and preparation costs, with radiotracer costs estimated by both vendor list pricing and proprietary institutional pricing. The primary outcome was a comparison of each hypothetical threshold to the clinical reality in which all subjects received MAG-3, and the results were supported by univariate sensitivity analysis. ResultsAnnual cost savings by serum creatinine threshold were as follows (threshold given in mg/dL): $17,319 if ≥1.0; $33,015 if ≥1.5; and $35,180 if ≥2.0. Annual cost savings by eGFR threshold were as follows (threshold given in mL/min/1.73 m2): $21,649 if ≤60; $28,414 if ≤45; and $32,744 if ≤30. Cost-savings inflection points were approximately 1.25 mg/dL (serum creatinine) and 60 mL/min/1.73m2 (eGFR). Secondary analysis by proprietary institutional pricing revealed similar trends, and cost savings of similar magnitude. Sensitivity analysis confirmed cost savings at all tested thresholds. ConclusionsReserving MAG-3 utilization for patients who have impaired renal function can impart substantial annual cost savings to a radiology department.