Table 4.

Studies evaluating clinical outcomes associated with ICUAW determined using the MRC sum score

Reference No.	Population	Incidence of ICUAW	Timing of Measurement	Univariate Analysis	P Value	Multivariate/Matched Analysis	Relative Risk (95% CI) or Weak Versus Not Weak	P Value
Prospective studies
144,147	MV ≥7 days	24/95 (25%)	D7 after awakening	↑ Duration of MV	<0.001	Prolonged weaning	HR 2.4 (1.4–4.2)	0.001
143,632	MV ≥7 days	75/115 (65%)	At awakening	Low MRCb delays successful extubation	0.001	Low MRCb delays successful extubation	HR 1.96 (1.27–3.02)	0.002
				↑ICU mortality	0.006	↑ICU mortality	OR 7.99 (0.99–64.29)	0.05
				↑Hospital mortality	0.02	↑Hospital mortality	OR 2.02 (1.03–8.03)	0.048
499	ICU stay ≥24 h	50/474 (11%)	At awakening	↑ICU mortality	<0.05	NA	NA	NA
	ICU stay >10 days	44/185 (24%)		↑ICU mortality	<0.05
10	MV ≥5 days	35/136 (26%)	At awakening	↑Duration of MV	<0.001	↓Hospital free days	41% (12–60%)	0.007
				↑ICU stay	<0.001	↓ICU free days	54% (67–36%)	0.001
				↓ICU-free to day 30	<0.001	↑Hospital mortality	OR 7.8 (2.4–25.3)	0.001
				↑Hospital stay	<0.001
				↓Hospital-free to day 60	<0.001
				↑ICU readmission	0.01
				↑Discharged to other location than home	0.01
				↑Hospital mortality	<0.001
82	SIRS and MV ≥48 h	13/39 (33%)a	ICU discharge	↑Duration of MV	0.001	↑Death before 180 days	NA	0.009
				↑ICU stay	0.005
				↓Functional outcome (Barthel index) at D28	0.01
				↑Death before 180 days	0.03
				↑Resources needed (cumulative TISS-28 scores)	0.008
722	ICU stay ≥7 days	17/33 (51%)	At awakening	Prolonged weaning	<0.05	NA	NA	NA
				↑ICU stay	0.001
				↓MIP	<0.001
410c	SICU	44/95 (46%)	At awakening	↑ICU stay	0.002	↑ICU stay	IRR 0.98 (0.97–0.98)	<0.001
				↑Hospital stay	0.001	↑Hospital stay	IRR 0.97 (0.97–0.98)	<0.001
				↑Mortality	0.006	↑Hospital mortality	OR 0.95 (0.90–0.99)	0.04
						↑Duration of MV		0.01
304	ICU stay ≥8days	227/415 (55%)	At awakening	↑Time to alive weaning	<0.001	↑Time to alive weaning	11d (7–22) versus 8d (5–14)	0.009
				↑Time to alive ICU discharge	<0.001	↑Time to alive ICU discharge	8d (2–14) versus 3d (0–8)	0.008
				↑ICU mortality	0.02	↑Time to alive hospital discharge	36d (16–83) versus 23d (13–41)	0.007
				↑Time to alive hospital discharge	<0.001	↓ 6 min WD	66m (0–207) versus 191m (90–270)	0.01
				↑Hospital mortality	<0.001	↑Total billed hopsitalization costs	23,277€ (15,370–36,147) versus 17,834€ (12,227–31,306)	0.04
				↓6 min WD	0.002	↑1 yr mortality	30.6% versus 17.2%	0.014
				↑Total billed hopsitalization costs	<0.001
				↑1 yr mortality	<0.001
487	Long-term ventilated (≥10 days), FEES clinically indicated	20/30 (67%)	Within 24 h of FEES	Pharangeal dysfunction		Pharangeal dysfunction
				PAS >1	0.038	PAS >1	9 (1.3–61.14)	0.038
				VPSR >1	0.014	VPSR >1	5.4 (1–28.5)	0.014
				Symptomatic aspiration (retrospective analysis)	0.003	Symptomatic aspiration	9.8 (1.6–60)	0.009
Retrospective studies
51	ARDS	27/45 (60%)	At awakening	↑ICU stay	0.001	NA	NA	NA
				↑Duration of MV (at 28d)	0.02

MV, mechanical ventilation; ICUAW, intensive care unit acquired weakness; MRC, medical research council; ICU, intensive care unit; NA, not available; CI, confidence interval; HR, hazard ratio; OR, odds ratio; IRR, incidence rate ratio. All studies used MRC <48 to diagnose ICUAW and to examine relationship with outcome unless explicitly stated:

^aankle dorsiflexion not included, ICUAW defined as sum score <35/50;

^bMRC sum score ≤41;

^cMRC sum score used as a continuous variable in the predictive models. Additional univariate analysis with MRC cut-off of 48 showed significant association with days on MV, ICU, and hospital stay.