Assessment of quadriceps muscle thickness using bedside ultrasonography by nurses and physicians in the intensive care unit: Intra- and inter-operator agreement

Table 1 Quadriceps thickness measured by 5 operators in a critical care setting

Operator		Thickness measured on three different attempts, mean (± SD) mm
ID	Level	1st	2nd	3rd
1	Consultant	17.14 (± 6.64)	17.49 (± 6.83)	17.44 (± 6.82)
2	Fellow	17.23 (± 6.81)	17.28 (± 6.92)	17.17 (± 6.81)
3	Fellow	17.82 (± 6.73)	17.87 (± 6.81)	17.80 (± 6.77)
4	Nurse	17.11 (± 6.54)	17.28 (± 6.49)	17.35 (± 6.57)
5	Nurse	17.52 (± 6.64)	17.42 (± 6.67)	17.52 (± 6.71)

SD: Standard deviation.

Table 2 Intraclass correlation coefficient for intraoperator variation among five operators

Operator		Measurements	ICC (95%CI); P value	Cronbach’s alpha
ID	Level
1	Consultant	1stvs 2nd	0.997 (0.992-0.999); < 0.0001	0.998
		1stvs 3rd	0.997 (0.993-0.998); < 0.0001	0.997
		2ndvs 3rd	0.998 (0.996-0.999); < 0.0001	0.998
		Overall	0.998 (0.997-0.999); < 0.0001	0.997
2	Fellow	1stvs 2nd	0.997 (0.995-0.998); < 0.0001	0.997
		1stvs 3rd	0.997 (0.995-0.997); < 0.0001	0.997
		2ndvs 3rd	0.997 (0.995-0.998); < 0.0001	0.997
		Overall	0.998 (0.997-0.999); < 0.0001	0.998
3	Fellow	1stvs 2nd	0.997 (0.995-0.999); < 0.0001	0.997
		1stvs 3rd	0.997 (0.995-0.999); < 0.0001	0.997
		2ndvs 3rd	0.998 (0.996-0.998); < 0.0001	0.998
		Overall	0.997 (0.995-0.999); < 0.0001	0.998
4	Nurse	1stvs 2nd	0.998 (0.996-0.999); < 0.0001	0.998
		1stvs 3rd	0.997 (0.995-0.999); < 0.0001	0.998
		2ndvs 3rd	0.999 (0.998-0.999); < 0.0001	0.999
		Overall	0.999 (0.998-0.999); < 0.0001	0.999
5	Nurse	1stvs 2nd	0.998 (0.996-0.999); < 0.0001	0.998
		1stvs 3rd	0.997 (0.995-0.998); < 0.0001	0.997
		2ndvs 3rd	0.998 (0.996-0.999); < 0.0001	0.998
		Overall	0.998 (0.997-0.999); < 0.0001	0.998

CI: Confidence interval; ICC: Intraclass correlation coefficient.

Table 3 Intraclass correlation coefficients for intraoperator variation among five operators for interoperator variation among 5 operators

Operator1comparison	ICC (95%CI); P value
	1st measurement	2nd measurement	3rd measurement
1 vs 2	0.979 (0.961, 0.988); < 0.001	0.976 (0.956, 0.987); < 0.001	0.977 (0.958, 0.987); < 0.001
1 vs 3	0.978 (0.960, 0.988); < 0.001	0.978 (0.960, 0.988); < 0.001	0.977 (0.959, 0.987); < 0.001
1 vs 4	0.965 (0.938, 0.981); < 0.001	0.955 (0.920, 0.975); < 0.001	0.962 (0.932, 0.979); < 0.001
1 vs 5	0.979 (0.963, 0.989); < 0.001	0.967 (0.942, 0.982); < 0.001	0.971 (0.948, 0.984); < 0.001
2 vs 3	0.988 (0.979, 0.994); < 0.001	0.984 (0.971, 0.991); < 0.001	0.982 (0.967, 0.990); < 0.001
2 vs 4	0.966(0.938, 0.981); < 0.001	0.963 (0.933, 0.979); < 0.001	0.966 (0.939, 0.981); < 0.001
2 vs 5	0.980(0.964, 0.989); < 0.001	0.975 (0.956, 0.986); < 0.001	0.978 (0.960, 0.988); < 0.001
3 vs 4	0.966 (0.939, 0.981); < 0.001	0.969 (0.945, 0.983); < 0.001	0.968 (0.942, 0.982); < 0.001
3 vs 5	0.983 (0.969, 0.991); < 0.001	0.979 (0.962, 0.988); < 0.001	0.980 (0.964, 0.989); < 0.001
4 vs 5	0.988 (0.978, 0.993); < 0.001	0.989 (0.980, 0.994); < 0.001	0.985 (0.973, 0.992); < 0.001
Overall	0.977 (0.965, 0.986); < 0.001	0.974 (0.960, 0.984); < 0.001	0.975 (0.961, 0.985); < 0.001

¹1: Consultant; 2 and 3: Fellow; 4 and 5: Nurse. CI: Confidence interval; ICC: Intraclass correlation coefficient.