Assessing the burden of illness from cervical dystonia using the Toronto Western Spasmodic Torticollis Rating Scale scores and health utility: a meta-analysis of baseline patient-level clinical trial data

Figures & data

Figure 1. Forest plot—burden of disease by means of TWSTRS in patients with CD. Note: D + L: DerSimonian and Laird random effects model and IPD: meta-regression using individual-patient data. Clinical trial study ID (registration number): Y-47-52120-051 (NCT00257660), Y-97-52120-045 (NA), Y-97-52120-045b (NA), Y-79-52120-131 (NCT00833196), Y-47-52120-731 (NCT00288509) and Y-97-52120-020 (NA); ClinicalTrials.gov. ES: estimate; Cl: confidence interval.

Table 1. Summary statistics of TWSTRS total and sub-scale scores and demographic characteristics of each trial.

Trials	NCT00257660	NCT00288509	NCT00833196	Y-47-52120-045	Y-47-52120-045b
n	127	87	404	157	132
Age 18–30 (%)	4.31	3.45	4.46	2.92	3.05
Age 31–40 (%)	12.07	10.34	12.86	9.49	9.16
Age 41–50 (%)	24.14	19.54	25.99	30.66	30.53
Age 51–60 (%)	30.17	31.03	26.49	24.82	25.19
Age 61–70 (%)	18.97	22.99	20.05	21.17	20.61
Age >70 (%)	10.34	12.64	10.15	10.95	11.45
Male (%)	33.9	40.2	35.2	39.5	37.9
Height (cm)	168.8	169.6	–	168.4	168.2
Weight (kg)	75.9	77.2	72.8	73.9	74.0
TWSTRS
TWSTRStotal (SD)	44.88 (8.4)	45.31 (8.2)	36.66 (10.8)	44.91 (8.4)	44.51 (8.8)
TWSTRSdisability (SD)	13.21 (4.27)	12.70 (4.31)	10.64 (5.87)	13.34 (4.46)	13.64 (4.22)
TWSTRSpain (SD)	10.57 (4.59)	9.99 (4.57)	6.57 (4.85)	10.93 (4.01)	11.48 (4.41)
TWSTRSseverity (SD)	20.51 (3.32)	19.79 (4.29)	19.54 (3.76)	19.99 (3.14)	19.39 (3.63)

SD, standard deviation; TWSTRS, Toronto Western Spasmodic Torticollis Rating Scale.

Table 2. Disease severities in terms of mean TWSTRS total and sub-scale scores as measured by DerSimonian and Laird method in patients with CD.

TWSTRS (full range)	Overall estimate	95% CI	Test of homogeneity
Total (0–85)	43.23	39.31–47.15	<0.0001
Disability (0–30)	12.37	11.35–13.40	<0.0001
Pain (0–20)	9.37	7.71–11.02	<0.0001
Severity (0–35)	19.79	19.43–20.15	0.089

CI, confidence interval; TWSTRS, Toronto Western Spasmodic Torticollis Rating Scale.

Table 3. Disease severities in terms of mean TWSTRS total associated with age groups measured by meta-regression in patients with CD.

TWSTRS (full range)	Overall estimate	95% CI	p Value	Coefficient (standard error)
Age 18–30	40.72	37.16–44.27	<0.0001
Age 31–40	1.68	−2.02–5.37	0.374
Age 41–50	5.89	2.48–9.30	0.001
Age 51–60	3.90	0.50–7.31	0.025
Age 61–70	3.16	−0.31–6.63	0.074
Age >70	3.43	−0.29–7.14	0.071
Variance
Level 1 (patients)				89.75 (4.30)
Level 2 (trials)				5.55 (1.41)

CI, confidence interval; TWSTRS, Toronto Western Spasmodic Torticollis Rating Scale.

Figure 2. Mapping of TWSTRS score to observed health utility. Note: R², r-squared (coefficient of determination), a statistical measure of how well a regression line approximates real data points, an r-squared of 1.0 (100%) indicates a perfect fit. TWSTRS, Toronto Western Spasmodic Torticollis Rating Scale.