German version of the Chelsea Critical Care Physical Assessment Tool (CPAx-GE): translation, cross-cultural adaptation, validity, and reliability

Figures & data

Figure 1. Step-wise translation and cross-cultural adaptation based on [14,15].

Table 1. Description of measured instruments, their constructs, and schedule.

Measurement instrument	Description, validity, and reliability	Construct (ICF component)	Visits^a
Medical Research Council sum score (MRC-SS)^b	Measures strength on a scale from 0 (no contraction) to 5 (normal strength) in 6 bilateral muscle groups, maximal summed score of 60 Reference standard to measure ICUAW (MRC-SS <48) [1], not validated Performance-based, volitional test (participants who were unable to follow at least 3 out of 5 commands, were assessed based on observation during physiotherapy) Established reliability in responsive, critically ill patients (ICC = 0.95) [19]	Muscle functions (b730–b749)	V1, V2, V3, V4
Functional Independence Measure (FIM)^b	18-item scale that evaluates assistance in activities of daily living such as self-care, sphincter control, locomotion, or communication on a scale from 1 (completely dependent) to 7 (completely independent) Multidimensional, performance-based, observational No established reliability and validity in the critically ill patient	Diverse body functions, activities, and participation	V1, V3, V4
ICU Mobility Scale (IMS)^b	Describes the highest level of mobility in critically ill adults from 0 (lying in bed with no active movement) to 10 (walking independently without aids) Performance-based, observational Good interrater reliability (weighted Kappa 0.83) [20] and established construct and predictive validity [21]	Mobility (d4)	V1, V2, V3, V4
Peak Cough Flow (PCF)^b	Assessed with a peak flow meter (Vitalograph Model 4300, Vitalograph Ltd., Ennis, Ireland) during volitional coughing in extubated or tracheotomised participants who were able to follow at least 3 out of 5 commands Performance-based, volitional No established reliability and validity in the critically ill patient	Additional respiratory functions (b450)	V1, V3, V4
Bogenhausener Dysphagia sum-score (BODS)^b	Rates dysphagia severity from 2 (no dysphagia) to 16 (severe dysphagia) by evaluating saliva swallowing and oral intake Performance-based, observational No established reliability and validity in the critically ill patient	Swallowing (b5105)	V1, V3, V4
Sequential Organ Failure Assessment Score (SOFA)^c	Describes the degree of organ dysfunction from 0 (normal) to 4 (most abnormal) for six vital organs Observational (biological and physiological variables) Content validity established by a consensus meeting [22], excellent interrater reliability (ICC = 0.89) [23]	Body structures	V1, V2, V3
Glasgow Coma Scale (GCS)^c	Assessment of consciousness since 1974 Performance-based, observational Reliability has been summarised as good and its worldwide use validated its relevance in neurologically impaired patients [24]	Mental functions (b1), movement functions (b750–b789)	V1, V2, V3
Richmond Agitation Sedation Scale (RASS)^c	Used to titrate sedation ranging from unarousable (–5) to calm and alert (0) to combative (+4) Performance-based, observational confirmed construct validity and high interrater reliability (ICC > 0.9) [25]	Mental functions (b1)	V1, V2, V3

^a V1: baseline, assessed between day 4 and 7; V2: ICU stay, assessed from day 5 every Tuesday and Friday until ICU discharge or a maximum of 10 assessments; V3: ICU discharge, assessed at ICU discharge; V4: hospital discharge, assessed at hospital discharge.

^b Performed or collected routinely by trained physiotherapists.

^c Extracted from routinely collected data via Patient Data Management System; the SOFA is routinely assessed daily at approximately 6 am, GCS and RASS were extracted at the time before physiotherapy.

Figure 2. Study flow. V1: visit at baseline; V2: visit at ICU stay; V3: visit at ICU discharge; V4: visit at hospital discharge.

Table 2. Demographics and characteristics of study participants (n = 58).

Variables	Participants
Age (years)	68 [56, 73]
Gender (male)	41 (70.7%)
BMI (kg/m^2)	26 [22.8, 29.1]
Weight (kg)	75.5 [70, 94]
APACHE II score (0–71)^a	32 [28, 36]
SOFA score (0–24)^a	12 [10, 14]
ICU diagnosis on ICU admission
Cardiac surgery	15 (25.9%)
Other surgery	7 (12.1%)
Respiratory insufficiency	15 (25.9%)
Hemodynamic insufficiency	13 (22.4%)
Trauma	5 (8.6%)
Neurology/neurosurgery	–
Gastroenterology	1 (1.7%)
Other	2 (3.4%)
ICU days until study inclusion	3.84 [3.41, 4.70]
Length of stay in ICU (days)^b	7.97 [6.69, 12.85]
Duration of mechanical ventilation (days)^b	6.81 [5.30, 11.51]
Tracheostomy^b	15 (25.9%)
ICU readmission^b	7 (12%)
Length of stay in hospital (days)^b	21.08 [11.72, 27.18]
ICU mortality^b	8 (13.8%)
ICU and hospital mortality^b	9 (15.5%)
ICU discharge destination
Hospital wards	34 (58.6%)
External ICU	13 (22.4%)
External hospital	3 (5.2%)
Died	8 (13.8%)
Hospital discharge destination
Rehabilitation	24 (41.4%)
External hospital	20 (34.5%)
Home	5 (8.5%)
Died	9 (15.5%)

BMI: body mass index; APACHE: Acute Physiology and Chronic Health Evaluation; SOFA: Sequential Organ Failure Assessment; ICU: intensive care unit. Data are presented as median [25%, 75%] or frequencies n (%).

^a ICU admission.

^b At original hospital (excluding external hospitals).

Table 3. Hypothesis-testing for construct, cross-sectional, and cross-cultural validity of the CPAx-GE.

No.	Prior hypothesis	n	Spearman’s rank correlation coefficient (r)	Confirmed
ICU baseline (V1), n = 58
1	CPAx with MRC-SS (r = 0.5–0.8)^a	58	0.639	Yes
2	CPAx with FIM (r = 0.4–0.7)	58	0.554	Yes
3	CPAx with IMS (r = 0.6–0.9)	58	0.711	Yes
4	CPAx with BODS (r = 0 to −0.3)	58	–0.294	Yes
5	CPAx with SOFA (r= −0.4 to −0.7)^a	58	–0.341	No
6	CPAx with GCS (r = 0.5–0.8)^a	58	0.603	Yes
7	CPAx with RASS (r = 0.3–0.6)^a	58	0.485	Yes
Total of accepted hypotheses for V1: 6 out of 7 (86%)
ICU discharge (V3), n = 50
8	CPAx with MRC-SS (r = 0.6–0.9)^a	50	0.809	Yes
9	CPAx item 10 with MRC-SS (r > 0.7)	50	0.775	Yes
10	CPAx with FIM (r > 0.7)^a	50	0.811	Yes
11	CPAx with IMS (r > 0.7)	50	0.883	Yes
12	CPAx item 2 with PCF (r = 0.4–0.7)^a	35	0.524	Yes
13	CPAx with BODS (r= −0.3 to −0.6)	50	−0.540	Yes
14	CPAx with SOFA (r= −0.4 to −0.7)^a	50	−0.482	Yes
15	CPAx with GCS (r = 0.5–0.8)^a	50	0.781	Yes
16	CPAx with RASS (r = 0.2–0.4)	50	0.082	No
Total of accepted hypotheses for V3: 8 out of 9 (89%)
Hospital discharge (V4), n = 32
17	CPAx with MRC-SS (r = 0.5–0.8)^a	31	0.674	Yes
18	CPAx item 10 with MRC-SS (r > 0.7)	31	0.391	No
19	CPAx with FIM (r > 0.7)^a	32	0.820	Yes
20	CPAx with IMS (r > 0.7)	32	0.856	Yes
21	CPAx item 2 with PCF (r = 0.4–0.7)^a	27	0.432	Yes
22	CPAx with BODS (r = 0 to −0.3)	32	0.027	Yes
Total of accepted hypotheses for V4: 5 out of 6 (83%)
Total of accepted hypotheses for complete pathway: 19 out of 22 (86%)

MRC-SS: Medical Research Council sum score; FIM: Functional Independence Measure; IMS: ICU Mobility Scale; BODS: Bogenhausener Dysphagia sum-score (BODS); SOFA: Sequential Organ Failure Assessment Score; GCS: Glasgow Coma Scale; RASS: Richmond Agitation Sedation Scale; PCF: Peak Cough Flow.

^a Cross-cultural validity: hypothesis based on original CPAx [10].

Figure 3. The modified Bland-Altman plot compares the treating versus the observing physiotherapist (n = 49) with the modified “true value varies” method which adjusts for repeated measurements with an unequal number of measurements for each individual. Mean/bias = –0.13 ± 0.15 (95% CI –0.43 to 0.18) and 95% limits of agreement: lower limit of agreement = –2.04 (95% CI –2.65 to –1.60), upper limit of agreement = 1.79 (95% CI 1.35 to 2.40), within-subject variance = 0.50 ± 0.22, between-subjects variance = 0.46 ± 0.28.

Table 4. Intraclass correlation coefficients (ICCs) for interrater reliability of the CPAx-GE.

Visit	Item	ICC (95% CI)	SEM	SDC	Cronbach’s α
V1 (ICU baseline)	Total CPAx score	0.984 (0.85–0.999)	0.500	1.386	0.85
V2 (ICU stay)	Total CPAx score	0.998 (0.991–1)	0.483	1.339	0.94
V3 (ICU discharge)	Total CPAx score	0.995 (0.992–0.997)	0.688	1.907	0.93
V4 (Hospital discharge)	Total CPAx score	0.979 (0.809–0.999)	0.500	1.386	0.61
Combined (V1–4)^a	Total CPAx score	0.996 (0.995–0.998)	0.680	1.885
Combined (V1–4)^a	Respiratory function	0.919 (0.914–0.948)	0.303	0.840
Combined (V1–4)^a	Cough	0.993 (0.993–0.993)	0.102	0.283
Combined (V1–4)^a	Moving within the bed	0.902 (0.866–0.951)	0.297	0.823
Combined (V1–4)^a	Supine to sitting on the edge of the bed	0.970 (0.971–0.974)	0.237	0.657
Combined (V1–4)^a	Dynamic sitting	0.976 (0.974–0.978)	0.236	0.654
Combined (V1–4)^a	Standing balance	0.974 (0.963–0.983)	0.181	0.502
Combined (V1–4)^a	Sit to stand	0.967 (0.957–0.973)	0.291	0.807
Combined (V1–4)^a	Transfers	0.967 (0.959–0.968)	0.333	0.923
Combined (V1–4)^a	Stepping	0.968 (0.953–0.962)	0.291	0.807
Combined (V1–4)^a	Grip strength	0.995 (0.995–0.996)	0.102	0.283

^a Corrected for multiple assessments.

Wild D, Grove A, Martin M, et al. Principles of good practice for the translation and cultural adaptation process for patient-reported outcomes (PRO) measures: report of the ISPOR Task Force for Translation and Cultural Adaptation. Value Health. 2005;8(2):94–104.

 PubMed Web of Science ®Google Scholar

Beaton DE, Bombardier C, Guillemin F, et al. Guidelines for the process of cross-cultural adaptation of self-report measures. Spine. 2000;25(24):3186–3191.

 PubMed Web of Science ®Google Scholar

Stevens RD, Marshall SA, Cornblath DR, et al. A framework for diagnosing and classifying intensive care unit-acquired weakness. Crit Care Med. 2009;37(10 Suppl.):S299–S308.

 PubMedGoogle Scholar

Hermans G, Clerckx B, Vanhullebusch T, et al. Interobserver agreement of Medical Research Council sum-score and handgrip strength in the intensive care unit. Muscle Nerve. 2012;45(1):18–25.

 PubMed Web of Science ®Google Scholar

Hodgson C, Needham D, Haines K, et al. Feasibility and inter-rater reliability of the ICU Mobility Scale. Heart Lung. 2014;43(1):19–24.

 PubMed Web of Science ®Google Scholar

Tipping CJ, Bailey MJ, Bellomo R, et al. The ICU Mobility Scale has construct and predictive validity and is responsive. Ann Am Thorac Soc. 2016;13(6):887–893.

 PubMed Web of Science ®Google Scholar

Vincent JL, Moreno R, Takala J, et al. The SOFA (Sepsis-related Organ Failure Assessment) score to describe organ dysfunction/failure. On behalf of the Working Group on Sepsis-Related Problems of the European Society of Intensive Care Medicine. Intensive Care Med. 1996;22(7):707–710.

 PubMed Web of Science ®Google Scholar

Arts DG, de Keizer NF, Vroom MB, et al. Reliability and accuracy of Sequential Organ Failure Assessment (SOFA) scoring. Crit Care Med. 2005;33(9):1988–1993.

 PubMed Web of Science ®Google Scholar

Teasdale G, Maas A, Lecky F, et al. The Glasgow Coma Scale at 40 years: standing the test of time. Lancet Neurol. 2014;13(8):844–854.

 PubMed Web of Science ®Google Scholar

Sessler CN, Gosnell MS, Grap MJ, et al. The Richmond Agitation-Sedation Scale: validity and reliability in adult intensive care unit patients. Am J Respir Crit Care Med. 2002;166(10):1338–1344.

 PubMed Web of Science ®Google Scholar

Corner EJ, Wood H, Englebretsen C, et al. The Chelsea Critical Care Physical Assessment Tool (CPAx): validation of an innovative new tool to measure physical morbidity in the general adult critical care population; an observational proof-of-concept pilot study. Physiotherapy. 2013;99(1):33–41.

 PubMed Web of Science ®Google Scholar

Data availability statement

The dataset supporting the conclusions of this article is included within the article as a Supplementary Material (Supplementary Material 5).