The Northwick Park Therapy Dependency Assessment scale: a psychometric analysis from a large multicentre neurorehabilitation dataset

Figures & data

Table 1. Characteristics of the study population (N = 2505).

Characteristics
Age, years, mean (SD) [range]	50.9 (15.9) [14–91]
Length of stay, days, mean (SD) [range]	83.3 (77) [4–945]
Male, n (%)	1517 (60.6)
Diagnosis, n (%)
Acquired Brain Injury	1602 (64.0)
Stroke	786 (49.1)
Traumatic	435 (27.2)
Tumour	122 (7.6)
Anoxia	101 (6.3)
Inflammatory	60 (3.7)
Other	98 (6.1)
Progressive condition	242 (9.7)
Spinal cord injury	191 (7.6)
Peripheral neurology	116 (4.6)
Other	173 (6.9)
Unknown	184 (7.2)
	Admission	Discharge	Paired t tests t/df/p value
Rehabilitation scores, mean (SD) [range]
NPTDA total	18.1 (9.1), [0–57]	18.5 (9.9), [0–55]	−1.77/1415/(0.077)
NPTDA therapy hours
Total hours per week	18.9 (16.4), [0–227]	18.4 (16.2), [0–214]	1.33/1415/(0.184)
RCS	10.4 (2.0), [2–15]	7.8 (2.9), [0–15]	41.37/1885/(<0.0001)
Care + medical + nursing	5.3 (1.6), [0–9]	3.6 (2.1), [0–9]	38.18/1885/(<0.0001)
Therapy	5.1 (0.9), [0–6]	4.2 (1.4), [0–6]	28.01/1885/(<0.0001)
FIM	67.1 (30.6), [18–126]	89.5 (32.2), [18–126]	−42.46/1656/(<0.0001)
FIM motor	44.7 (24.9), [13–91]	63.1 (26.1), [13–91]	−40.58/1650/(<0.0001)
FIM cognitive	22.5 (9.8), [5–35]	26.6 (8.7), [5–35]	−28.19/1658/(<0.0001)

NPTDA, Northwick Park Therapy Dependency Assessment Scale; RCS, Rehabilitation Complexity Scale; and FIM, Functional Independence Measure.

Table 2. Exploratory factor analysis – pattern matrix loadings for the hypothesised model (direct patient care) and confirmatory factor analysis – factor loadings.

									Confirmatory factor analysis
Item (domain)	Range	Mean (SD)	Item-total correlations	First principal component	Factor 1 Physical (17% variance)	Factor 2 Psychosocial (12% variance)	Factor 3 Discharge planning (8% variance)	Factor 4 Activities (6% variance)	Factor 1 Physical	Factor 2 Psychosocial	Factor 3 Discharge planning	Factor 4 Activities
1. Medical (A)	0–4	1.44 (1.09)	0.26	0.429	0.542				0.522
2. Splinting (A)	0–8	0.70 (1.32)	0.33	0.427	0.445				0.288
3. Seating (A)	0–4	0.99 (1.18)	0.24	0.401	0.706				0.471
4. Physical therapy (A)	0–4	2.58 (1.27)	0.22	0.347	0.585				0.408
5. Tracheostomy (B)	0–4	0.14 (0.60)	0.13	−0.388	0.491				0.451
6. Swallowing (B)	0–4	0.33 (0.79)	0.26	0.447	0.570				0.551
7. Nutrition (B)	0–4	0.51 (0.94)	0.28	0.464	0.655				0.585
8. Communication (B)	0–4	0.39 (0.93)	0.33	0.515	0.409				0.441
9. Speech/language (B)	0–4	0.74 (1.11)	0.38	0.543	0.348			0.498	0.452			(0.187)
10. Personal/self-care (C)	0–4	1.11 (1.21)	0.32	0.404				0.429				0.259
11. Domestic activity (C)	0–4	0.76 (1.09)	0.21	0.516	(−0.313)			0.709				0.678
12. Vocational activity (C)	0–4	0.44 (0.88)	0.32	0.485				0.687				0.586
13. Cognitive (D)	0–4	0.93 (1.28)	0.23	0.372		0.552				0.440
14. Behavioural (D)	0–4	0.31 (0.86)	0.34	0.510		0.827				0.617
15. Emotional/mood (D)	0–4	0.60 (0.99)	0.39	0.516		0.696				0.586
16. Family support (D)	0–4	0.48 (0.96)	0.47	0.606		0.562				0.517
17. Emotional – staff (D)	0–4	0.54 (0.96)	0.49	0.653		0.746				0.677
18. Discharge (E)	0–4	1.02 (1.27)	0.27	0.570			0.679				0.627
19. Benefits (E)	0–4	0.33 (0.77)	0.33	0.424			0.491				0.507
20. Equipment (E)	0–4	0.48 (0.91)	0.22	0.486			0.759				0.498
21. Community (E)	0–4	0.43 (0.99)	0.15	0.485			0.609				0.443
22. Key working (E)	0–4	1.07 (1.09)	0.39	0.418			0.417				0.505
23. Meetings (F)	0–2	0.83 (0.91)	0.33
24. Reports (F)	0–2	0.69 (0.83)	0.09
25. Groups (F)	0–2	0.49 (0.76)	0.23
26. Clinical attendance (F)	0–2	0.12 (0.44)	0.15

NPTDA, Northwick Park Therapy Dependency Assessment; Extraction Method, Principal Component Analysis; Rotation Method: Promax; all loadings < 0.3 removed for clarity. Domains: (A) physical/handling programme, (B) basic functions, (C) activities of daily living, (D) cognitive/psychosocial/family support, (E) preparing for discharge, (F) additional activities; (G) special input not shown.

Table 3. Descriptive statistics of the 26 NPTDA items: scores on admission and discharge and change scores (N = 1418).

	Admission	Discharge			Paired t tests
Domain/Item Factor	Mean (SD)	Mean (SD)	Mean difference	95% CI	t	df	p Value
Direct patient care
(A) Physical/handling programme (range 0–16)
1. Medical (A)	1.69 (1.11)	1.18 (1.05)	0.51	−0.45 to 0.57	17.35	1417	<0.0001
2. Splinting (A)	0.68 (1.31)	0.62 (1.19)	0.06	−0.01 to 0.13	1.84	1365	0.066
3. Seating (A)	1.25 (1.26)	0.61 (0.96)	0.64	0.58 to 0.71	19.23	1365	<0.0001
4. Physical therapy (A)	2.89 (1.13)	2.16 (1.35)	0.72	0.65 to 0.79	19.49	1365	<0.0001
(B) Basic functions (range 0–20)
5. Tracheostomy (B)	0.19 (0.70)	0.08 (0.43)	0.11	0.07 to 0.14	6.11	1365	<0.0001
6. Swallowing (B)	0.42 (0.87)	0.18 (0.58)	0.25	0.21 to 0.29	11.02	1416	<0.0001
7. Nutrition (B)	0.57 (0.99)	0.37 (0.80)	0.19	0.15 to 0.24	8.76	1416	<0.0001
8. Communication (B)	0.44 (0.95)	0.28 (0.75)	0.16	0.11 to 0.21	7.06	1416	<0.0001
9. Speech/language (B)	0.83 (1.13)	0.55 (0.96)	0.28	0.23 to 0.34	10.32	1416	<0.0001
Physical (A + B)	8.17 (5.75)	5.45 (4.43)	2.73	2.46 to 2.99	20.45	1365	<0.0001
(C) Activities of daily living (range 0–12)
10. Personal/self-care (C)	1.35 (1.25)	0.84 (1.07)	0.51	0.43 to 0.58	13.81	1416	<0.0001
11. Domestic activity (C)	0.74 (1.09)	0.85 (1.13)	−0.11	−0.18 to −0.04	−3.24	1416	0.001
12. Vocational activity (C)	0.33 (0.78)	0.51 (0.93)	−0.18	−0.23 to −0.12	−6.65	1416	<0.0001
Activities (C)	2.41 (2.24)	2.18 (2.19)	0.22	0.09 to 0.35	3.42	1416	0.001
(D) Cognitive/psychosocial/family support (range 0–20)
13. Cognitive (D)	1.11 (1.34)	0.85 (1.24)	0.26	0.18 to 0.33	6.94	1416	<0.0001
14. Behavioural (D)	0.36 (0.91)	0.29 (0.77)	0.07	0.03 to 0.12	3.10	1416	0.002
15. Emotional/mood (D)	0.61 (0.98)	0.62 (0.97)	−0.01	−0.06 to 0.05	−0.21	1416	0.83
16. Family support (D)	0.44 (0.90)	0.54 (1.01)	−0.11	−0.16 to −0.05	−3.89	1416	<0.0001
17. Emotional – staff (D)	0.51 (0.91)	0.54 (0.95)	−0.03	−0.08 to 0.02	−1.34	1415	0.18
Psychosocial (D)	3.02 (3.45)	2.84 (3.32)	0.18	0.02 to 0.34	2.20	1415	0.028
(E) Preparing for discharge (range 0–20)
18. Discharge (E)	0.57 (1.00)	1.52 (1.33)	−0.95	−1.03 to −0.88	−24.37	1416	<0.0001
19. Benefits (E)	0.19 (0.57)	0.49 (0.90)	−0.29	−0.35 to −0.25	−12.39	1416	<0.0001
20. Equipment (E)	0.22 (0.65)	0.71 (1.05)	−0.50	−0.55 to −0.44	−16.83	1416	<0.0001
21. Community (E)	0.22 (0.72)	0.70 (1.24)	−0.48	−0.55 to −0.41	−13.27	1416	<0.0001
22. Key working (E)	0.90 (0.99)	1.21 (1.15)	−0.31	−0.36 to −0.26	−11.48	1416	<0.0001
Discharge planning (E)	2.09 (2.37)	4.63 (3.59)	−2.54	−2.72 to −2.35	−26.49	1416	<0.0001
Indirect patient care
(F) Additional activities (range 0–8)
23. Meetings (F)	0.79 (0.91)	0.89 (0.91)	−0.09	−0.15 to −0.04	−3.48	1416	0.001
24. Reports (F)	0.34 (0.63)	1.12 (0.81)	−0.78	−0.83 to −0.73	−30.53	1416	<0.0001
25. Groups (F)	0.37 (0.66)	0.66 (0.84)	−0.29	−0.34 to −0.25	−13.50	1416	<0.0001
26. Clinical attendance (F)	0.12 (0.44)	0.15 (0.47)	−0.03	−0.06 to −0.01	−2.08	1416	0.038
Total (F)	1.62 (1.46)	2.82 (1.78)	−1.20	−1.30 to −1.11	−24.09	1416	<0.0001

NPTDA, Northwick Park Therapy Dependency Assessment.

Items for which therapy inputs increase from admission to discharge are shown in bold.

Italics are shown the total scores from admission to discharge within the four factors.

Table 4. Pearson correlations between NPTDA direct patient care with RCS and FIM based on total and subscales scores on admission.

		Subscales
	NPTDA Direct patient care (A + B + C + D + E)	Physical (A + B)	Activities (C)	Psychosocial (D)	Discharge planning (E)
RCS	0.304*	0.435*	−0.153*	0.173*	−0.028
Care + medical + nursing	0.226*	0.360*	−0.196*	0.149*	−0.073*
Therapy	0.290*	0.346*	0.005	0.128*	0.069*
FIM	−0.249*	−0.492*	0.275*	−0.022	0.145*
Cognitive	−0.245*	−0.359*	0.172*	−0.217*	0.106*
Motor	−0.209*	−0.462*	0.265*	0.059**	0.132*

Domains: (A) physical/handling programme, (B) basic functions, (C) activities of daily living, (D) cognitive/psychosocial/family support, (E) preparing for discharge; RCS, Rehabilitation Complexity Scale; FIM, Functional Independence Measure.

*p < 0.01 and **p < 0.05.