Table 12.

Ablation study results for severity quantification performance.

Methods	External 1 (CNUH)	External 2 (YNU)	External 3 (KNUH)
	MSE (95% CI)	MSE (95% CI)	MSE (95% CI)
Proposed model	1.441 (0.760-2.122)	1.435 (1.195–1.676)	1.458 (1.147–1.768)
w/o pre-train	1.737 (1.037–2.437)	2.319${}^{**}$ (1.907–2.732)	1.835${}^{*}$ (1.402–2.268)
w/o Transformer	1.544 (0.882–2.206)	1.977${}^{**}$ (1.682–2.272)	1.374 (1.091–1.657)
w/o PCAM	1.436 (0.777–2.095)	2.205${}^{**}$ (1.881–2.529)	1.353 (1.058–1.648)
w/o position embedding	1.447 (0.838–2.056)	1.504 (1.257–1.750)	1.522 (1.237–1.807)

Note:${}^{*}$, ${}^{**}$ denote the better performance of ours with statistical significance ($p<0.05$, $p<0.001$). CI: confidence interval.