Development of a risk score for scoliosis in children with cerebral palsy

Figures & data

Table 1. Demographic distribution for included variables. Values are frequency (%)

Variable/category	n = 654
GMFCS ^a
I	264 (40)
II	117 (18)
III	53 (8.1)
IV	115 (18)
V	105 (16)
Sex
Male	372 (57)
Female	282 (43)
CP ^b subtype
Spastic unilateral	268 (41)
Spastic bilateral	216 (33)
Ataxic	41 (6.3)
Dyskinetic	93 (14)
Mixed type	22 (3.4)
Missing	14 (2.1)
Birthyear
2000	113 (17)
2001	144 (22)
2002	191 (29)
2003	206 (32)
Epilepsy, yes	222 (34)
Hip surgery ^c	53 (8.1)
Worst side
MP ^d 41–100%	45 (6.9)
Limited hip extension ≤ –5є	35 (5.4)
Limited knee extension ≤ –5є	91 (14)

^aGMFCS = Gross Motor Function Classification System.

^bCP = cerebral palsy.

^cFemur-, pelvic osteotomy, adductor psoas tenotomy.

^dMP = migration percentage.

Figure 1. Graph showing the proportion of children with scoliosis correctly predicted to develop scoliosis before the age of 16 years (the sensitivity) and the proportion of children without scoliosis correctly predicted not to develop scoliosis before the age of 16 years (the specificity) for choice of a cutoff to indicate a high-risk individual.

Table 2. Odds ratios (OR) with 95% confidence intervals (CI) for possible predictors of scoliosis measured at the age of 5 (steps 1 and 2) ^a

Risk factors	Step 1 Univariable analysis OR (95% CI)	Step 2 Multivariable analysis, first regression OR (95% CI)	Step 3 Multivariable analysis, last regression OR (95% CI)	Step 4 L1-penalized regression OR
GMFCS I–III	Ref.	Ref.	Ref.
GMFCS IV	12 (5.6–25)	10 (4.2–24)	9.9 (4.6–21)	8.4
GMFCS V	41 (20–83)	25 (9.5–65)	29 (14–61)	21
Female	1.7 (1.1–2.6)	1.9 (1.1–3.4)	1.9 (1.1–3.3)	1.8
Epilepsy	3.9 (2.5–6.2)	1.6 (0.9–2.9)	1.9 (1.1–3.2)	1.6
Knee extension ≤ –5°	4.3 (2.6–7.1)	1.9 (1.0–3.7)	1.9 (1.0–3.4)	1.8
Hip extension ≤ –5°	3.5 (1.7–7.3)	1.2 (0.5–3.0)		1.2
Spastic CP	0.4 (0.3–0.7)	1.3 (0.7–2.4)		1.2
Hip surgery	7.8 (4.3–14)	1.3 (0.6–2.9)		1.3
MP > 40%	5.9 (3.1–11)	1.3 (0.6–3.0)		1.3

^a Step 3 shows the significant factors remaining after the stepwise procedure, which predict the development of scoliosis before the age of 16 years for children with cerebral palsy (CP).

Step 4 shows the ORs from the sensitivity analysis using L1-penalized regression.

Spastic CP includes uni- and bilateral spasticity.

For CP, GMFCS, Hip surgery, and MP, see Table 1

Table 3. Risk of developing scoliosis before the age of 16, corresponding to each risk score level

Risk score	Risk of scoliosis (%)
< –2.2	0 to 10
–2.2 to –1.4	10 to 20
–1.3 to –0.85	20 to 30
–0.85 to –0.41	30 to 40
–0.41 to 0	40 to 50
0 to 0.41	50 to 60
0.41 to 0.85	60 to 70
0.85 to 1.4	70 to 80
1.4 to 2.2	80 to 90
> 2.2	90 to 100