Table 3.

Sensitivity and specificity of peroneal CMAP reduction to diagnose critical illness myopathy and/or neuropathy

		Time of development	Sensitivity	Specificity
		ICU day	(True-positive rate)	(True-negative rate)
	Number (%)	Median (IQR)
1. One peroneal CMAP reduced according to criterion A	64 (69.6)	3 (2–5)	28/28 = 100%	28/64 = 44%
2. One peroneal CMAP reduced according to criterion B	49 (53.3)	4 (2–7)	28/28 = 100%	43/64 = 67%
3. Both peroneal CMAPs reduced according to criterion A	26 (28.3)	6 (3–10)	21/28 = 75%	59/64 = 92%
4. One peroneal CMAP reduced according to criterion A plus the contralateral peroneal CMAP reduced according to criterion B	23 (25.0)	6 (3–10)	21/28 = 75%	62/64 = 97%
5. Both peroneal CMAPs reduced according to criterion B	16 (17.4)	6 (3.5–10)	16/28 = 57%	64/64 = 100%

Criterion A = CMAP amplitude reduced by more than 25% of its initial value (at ICU admission) but less than two standard deviations (SDs) of its normal value. Criterion B = CMAP reduced by more than 2 SDs of its normal value. Note that the five categories are not mutually exclusive (for example, the 16 patients in category 5 are also included in category 2). CMAP, compound muscle action potential; ICU, intensive care unit; IQR, interquartile range.