Teaching parathyroid-sparing thyroidectomy: clinical and educational impact of near-infrared autofluorescence. Results of a retrospective case-control study

Purpose: To evaluate the impact of near-infrared autofluorescence (NIR-AF) on both 21 postoperative parathyroid function and the learning curve of surgeons performing total 22 thyroidectomy (TT). 23 Methods: We conducted a retrospective case–control study including 335 adult patients 24 undergoing TT for primary thyroid disease (181 with intraoperative NIR-AF guidance 25 [NIR-AF+] and 154 under conventional standard approach [NIR-AF−]). Primary endpoints 26 were transient hypocalcemia, transient hypoparathyroidism, and parathyroid gland 27 identification rate (PG-IR). To specifically explore learning dynamics, we evaluated the 28 influence of NIR-AF on the surgeons’ performance over time, comparing outcomes and 29 PG-IR across two consecutive NIR-AF utilization periods. Multivariate logistic regression was 30 used to identify independent predictors of postoperative PGs dysfunction. 31 Results: NIR-AF significantly increased PG-IR (90.7% vs. 70.5%) and was associated with 32 lower rates of transient hypocalcemia (46.3% vs. 60.2%, p=0.011) and transient 33 hypoparathyroidism (45.5% vs. 57.7%, p=0.041). On multivariate analysis, NIR-AF remained 34 an independent protective factor for transient hypocalcemia (OR 0.554, p=0.009) and 35 transient hypoparathyroidism (OR 0.606, p=0.040). Along the NIR-AF adoption timeline, PG-36 IR under white-light visualization progressively improved, suggesting a possible perceptual 37 calibration effect that may contribute to shorte-ning the learning curve for PG-sparing 38 thyroidectomy. Finally, short-term postoperative calcium levels were significantly higher in 39 the NIR-AF+ group. 40 Conclusion: NIR-AF improves intraoperative PGs identification and reduces early 41 postoperative parathyroid dysfunction after TT. Beyond its technical utility, fluorescence 42 guidance may act as an educational scaffold, potentially enhancing visual discrimination of 43 parathyroid tissue. Whether NIR‑AF independently accelerates the surgical learning curve 44 remains to be confirmed in prospective, surgeon-stratified studies.