Table 2.

The 2 × 2 contingency table for agreements between the Rex method and the standardized PEEP reduction method in the original dataset (MAFAI VENT)

	Rex analysis POSITIVE EFLT	Rex analysis NEGATIVE EFLT	Total n
PEEP reduction POSITIVE EFLT	45	11	56
PEEP reduction NEGATIVE EFLT	21	253	274
Total n	66	264	330

Using PEEP reduction from 5 cmH₂O to ZEEP as a gold standard: The Rex analysis method provides 90.3% agreement (95% CI 86.6–93.3%), 80.4% sensitivity (95% CI 67.6–89.8%) and 92.3% specificity (95% CI 88.5–95.2%). The positive and negative predictive value of Rex were 68.2% (58.2–76.7%) and 95.8% (93.1–97.5%) respectively. The Cohen’s k is 0.68 (95% CI 0.58–0.78), i.e., substantial agreement [17]