Early prediction of noninvasive ventilation failure in COPD patients: derivation, internal validation, and external validation of a simple risk score

Annals of Intensive Care

Table 3 Final model for prediction of NIV failure in the derivation cohort and points assigned to each variable

Variables	Regression coefficient β per unit increase	Category (j)	Assigned points
Respiratory rate at 1–2 h of NIV, breaths/min	0.062	< 30	0
		30–34	1
		35–39	2
		≥ 40	3
Heart rate at 1–2 h of NIV, beats/min	0.027	< 100	0
		100–119	1
		120–139	2
		≥ 140	3
pH at 1–2 h of NIV	− 15.851	≥ 7.35	0
		7.30–7.34	2
		7.25–7.29	3
		7.20–7.24	5
		< 7.20	8
GCS at 1–2 h of NIV	− 0.992	15	0
		14	2
		13	4
		12	6
		≤ 11	11
PaO₂/FiO₂ at 1–2 h of NIV, mmHg	− 0.005	≥ 150	0
		101–149	1
		≤ 100	2