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Table 4 Results of the weighted ANOVAs of quality items on the lifetime prevalence estimates

From: Prevalence of low back pain in children and adolescents: a meta-analysis

Quality item

k

p +

95%

C. I.

ANOVA results

   

p l

p u

 

Target population described:

     

 Yes

21

0.416

0.346

0.489

Q B(1) = 0.77, p = .380; R 2 = 0.0

 No

9

0.358

0.260

0.469

Q W(28) = 4942.26, p < .001

Non response described:

     

 Yes

5

0.486

0.401

0.572

Q B(1) = 4.42, p = .036; R 2 = 0.676

 No

20

0.384

0.343

0.427

Q W(23) = 1162.44, p < .001

Response rate reported:

     

 Yes

27

0.403

0.343

0.467

Q B(1) = 0.21, p = .648; R 2 = 0.0

 No

3

0.358

0.202

0.551

Q W(28) = 4910.99, p < .001

Direct reporting from subjects:

     

 Yes

26

0.411

0.344

0.480

Q B(1) = 0.87, p = .352; R 2 = 0.0

 No

4

0.326

0.190

0.498

Q W(28) = 4853.39, p < .001

Validated instrument:

     

 Yes

26

0.400

0.339

0.464

Q B(1) = 1.32, p = .250; R 2 = 0.015

 No

3

0.517

0.332

0.698

Q W(27) = 4754.11, p < .001

Delimitation of pain:

     

 Yes

20

0.472

0.413

0.532

Q B(1) = 17.98, p < .001; R 2 = 0.376

 No

10

0.266

0.205

0.338

Q W(28) = 2192.08, p < .001

Specification of pain:

     

 Questionnaire

16

0.399

0.316

0.487

Q B(1) = 0.00, p = .999; R 2 = 0.0

 Interview

14

0.399

0.311

0.494

Q W(28) = 4635.79, p < .001

  1. k: number of studies. p +: mean prevalence. p l and p u: lower and upper confidence limits of the 95% confidence interval around the mean prevalence. Q B: between-categories statistic to test the influence of the moderator variable on the prevalence rates. Q W: within-categories statistic to test the model misspecification. R 2: proportion of variance accounted for by the moderator variable. Five of the 12 quality items were not included in the table due to one of their categories being represented by one study only or by none (survey designed for studying prevalence rates, data collection was uniform, validated interview, validated exam, and memory period clear).