Would scan, but which scan? A cost-utility analysis to optimize preoperative imaging for primary hyperparathyroidism.

BACKGROUND: Minimally invasive parathyroidectomy for primary hyperparathyroidism depends on accurate preoperative localization. This study examines the cost-utility of sestamibi in combination with single photon emission computed tomography (sestamibi-SPECT); ultrasound; and 4-dimensional computed tomography (4D-CT).

METHODS: A decision tree was constructed for patients undergoing initial parathyroidectomy. Patients were randomized to 1 of 5 preoperative localization protocols: (1) ultrasound; (2) sestamibi-SPECT; (3) 4D-CT; (4) sestamibi-SPECT and ultrasound; and (5) sestamibi-SPECT and ultrasound and 4D-CT, if discordant (sestamibi-SPECT and ultrasound ± 4D-CT). From a societal perspective, all relevant costs were included. Input data were obtained from literature and Medicare. The incremental cost-utility ratio was determined in dollars per quality-adjusted life years ($/QALY). Sensitivity analyses were performed.

RESULTS: In the base-case, ultrasound was least expensive, with a cost of $6666, compared to $6773 (4-D CT); $7214 (sestamibi-SPECT and ultrasound ± 4D-CT); $7330 (sestamibi-SPECT); and $7371(sestamibi-SPECT and ultrasound). Sestamibi-SPECT and ultrasound ± 4D-CT were most cost-effective because improved localization resulted in fewer bilateral explorations. QALY were comparable across modalities. Compared to sestamibi-SPECT, ultrasound, 4D- CT, and sestamibi-SPECT and ultrasound ± 4D-CT resulted a win-win situation-costing less and accruing more utility. Sensitivity analyses demonstrated that the model was sensitive to surgery cost and diagnostic accuracy of imaging.

CONCLUSION: In our model, sestamibi-SPECT and ultrasound ± 4D-CT were the most cost-effective methods, followed by 4D-CT and ultrasound. Sestamibi-SPECT alone was least cost-effective. Cost-utilities were dependent on the sensitivities of ultrasound and 4D-CT and may vary by institution.