Properties of SF-6D when longitudinal data from 16,398 spine surgery procedures is applied to 9 national SF-6D value sets

Figures & data

Table 1. Characteristics of the study population

	Spinal stenosis	Disk herniation
Factor	n = 8,888	n = 7,510
Age, mean (SE)	66.6 (0.11)	45.7 (0.15)
BMI (SE)	27.8 (0.05)	26.4 (0.05)
Females, n (%)	3,999 (45)	3,345 (45)
Smokers, n (%)	826 (9)	950 (13)

Figure 1. SF-36 scores for spinal stenosis (n = 8,888) and disk herniation (n = 7,510) preoperatively (green dots) and 2 years postoperatively (blue triangles). The standard errors were less than 0.6 for all domains. PF = physical functioning, RP = role limitation due to physical problems, BP = bodily pain, GH = general health, VT = vitality, SF = social functioning, RE = role limitations due to emotional problems, MH = mental health.

Figure 2. Frequency of SF-6D states (triangles) before and after surgical treatment for spinal stenosis (n = 8,888) and disk herniation (n = 7,510).

Figure 3. Kernel density estimates of the SF-6D index distributions for 9 different national SF-6D value sets based on data from patients treated for spinal stenosis (n = 8,888) and patients treated for disk herniation (n = 7,510).

Figure 4. Kernel density estimates of the SF-6D index distributions for 9 different national SF-6D value sets based on a computer-generated data set consisting of all possible 18,000 SF-6D health states (111111 to 645655).

Table 2. Preop and postop SF-6D indices for 16,398 spine surgery patients based on different national value sets

Country	Preop		Postop		Effect size SRM (95% CI)
	Mean (SE)	Median (IQR)	Mean (SE)	Median (IQR)
Spinal stenosis (n = 8,888)
Australia	0.27 (0.0024)	0.26 (0.10–0.44)	0.48 (0.0031)	0.50 (0.24–0.70)	0.76 (0.74–0.78)
Brazil	0.58 (0.0010)	0.57 (0.51–0.63)	0.67 (0.0014)	0.67 (0.57–0.78)	0.70 (0.68–0.73)
China	0.54 (0.0015)	0.55 (0.45–0.64)	0.67 (0.0019)	0.68 (0.55–0.81)	0.72 (0.70–0.75)
Spain	0.37 (0.0023)	0.38 (0.24–0.51)	0.57 (0.0029)	0.58 (0.38–0.81)	0.75 (0.73–0.78)
Hong Kong	0.59 (0.0013)	0.55 (0.50–0.69)	0.70 (0.0017)	0.72 (0.54–0.84)	0.71 (0.69–0.73)
Lebanon	0.70 (0.0012)	0.70 (0.63–0.78)	0.79 (0.0014)	0.81 (0.69–0.92)	0.71 (0.69–0.74)
Portugal	0.75 (0.0010)	0.74 (0.69–0.81)	0.82 (0.0012)	0.83 (0.74–0.92)	0.67 (0.65–0.69)
UK	0.61 (0.0013)	0.61 (0.54–0.70)	0.72 (0.0015)	0.73 (0.61–0.84)	0.73 (0.71–0.76)
USA	0.81 (0.0006)	0.81 (0.77–0.85)	0.86 (0.0008)	0.86 (0.81–0.93)	0.69 (0.66–0.71)
Disk herniation (n = 7,510)
Australia	0.18 (0.0025)	0.15 (0.02–0.33)	0.59 (0.0034)	0.64 (0.40–0.83)	1.33 (1.29–1.36)
Brazil	0.54 (0.0011)	0.54 (0.48–0.59)	0.71 (0.0016)	0.69 (0.61–0.78)	1.18 (1.15–1.21)
China	0.47 (0.0018)	0.47 (0.36–0.58)	0.73 (0.0020)	0.75 (0.63–0.84)	1.29 (1.26–1.32)
Spain	0.27 (0.0026)	0.30 (0.12–0.43)	0.67 (0.0030)	0.74 (0.51–0.87)	1.34 (1.31–1.38)
Hong Kong	0.54 (0.0014)	0.50 (0.46–0.62)	0.76 (0.0018)	0.81 (0.66–0.87)	1.30 (1.27–1.33)
Lebanon	0.65 (0.0013)	0.65 (0.57–0.73)	0.84 (0.0015)	0.88 (0.76–0.94)	1.30 (1.27–1.33)
Portugal	0.71 (0.0012)	0.72 (0.65–0.78)	0.86 (0.0012)	0.88 (0.81–0.93)	1.21 (1.18–1.24)
UK	0.56 (0.0014)	0.56 (0.47–0.64)	0.77 (0.0016)	0.80 (0.68–0.86)	1.29 (1.26–1.32)
USA	0.79 (0.0007)	0.79 (0.74–0.83)	0.89 (0.0009)	0.90 (0.84–0.96)	1.17 (1.14–1.20)