SGS - Centre for Evidence Based Early Intervention

Initial validation of the Schedule of Growing Skills (SGS)

Margiad Elen Williams Bangor University

Content • • • • •

Background Validation process Step one Step two Conclusions

Background • Screening tools are used to identify children with possible developmental delay to enable subsequent more rigorous assessment. • Quick, inexpensive, and easy to use. • Should be as accurate as possible.

American Academy for Pediatrics (2006) • Published recommended psychometric criteria that all screening tools should meet. • Sensitivity – proportion of correctly identified children in need of further assessment. • Specificity – proportion of correctly identified children who are developing typically. • Both need to be at least 70%.

The SGS in Wales • Welsh Assembly Government introduced Flying Start (FS) Initiative. • SGS chosen as the developmental screening tool to evaluate FS Initiative. • Problems with scoring identified during IY Toddler trial (Hutchings et al., 2011).

Problems with SGS scoring • Windows of assessment vary. • Score highest item within scale regardless of performance on other items. • Cannot compare between groups or across time.

• Problems can be solved by developing way of scoring to yield a Developmental Quotient (DQ) score.

SGS Profile Form

Aims • To validate both the original and new DQ way of scoring the SGS. • Two step validation process. • Use of two data sets, the RCT of the IY Toddler programme and MRes project comparing the SGS and GMDS.

Step one Aim 1: Estimate appropriate cutoff for new SGS scoring method

Aim 2: Determine concurrent validity of both SGS scoring methods against GMDS

Step two Aim 1: Determine concurrent validity of both SGS scoring methods against Ages and Stages Questionnaire (ASQ)

Step one: Sample & Measures Participants • 39 children • Mean age 31 months • 61% male

Measures • Griffiths Mental Development Scales (GMDS) • Schedule of Growing Skills (SGS)

Step two: Sample & Measures Participants • 94 children • Mean age 22 months • 61% male

Measures • Ages and Stages Questionnaire (ASQ) • Schedule of Growing Skills (SGS)

Subscale comparisons Griffiths Mental Development Scales (GMDS)

Schedule of Growing Skills (SGS)

Ages and Stages Questionnaire (ASQ)

Locomotor

Gross motor

Gross motor

Performance & Eye-Hand Coordination (fine motor)

Manipulative & Visual (fine motor)

Fine motor

Language

Hearing, Speech, & Language

Communication

Personal-Social

Interactive & Self-care

Results: Step one Aim 1: Establishing cut-off point • Receiver Operating Characteristic (ROC) Curves • Explored three potential cut-off points: - DQ < 90 - DQ < 85 - DQ < 80

Results: Step one Aim 1: Establishing cut-off point SGS cut-off

AUC

Sensitivity

Specificity

DQ < 90

.794

90.83

67.88

DQ < 85

.779

74.18

81.55

DQ < 80

.789

65.83

91.90

• Most accurate cut-off is DQ < 85. • Both sensitivity and specificity levels > 70%

Results: Step one Aim 2: Concurrent validity with GMDS • Calculated: - Sensitivity - Specificity - Over-referral rates - Under-referral rates

Results: Step one Aim 2: Concurrent validity with GMDS Development area

SGS scoring

Sensitivity (%)

Specificity (%)

Overreferrals (%)

Underreferrals (%)

Locomotor

Original

16.67

100

0

12.80

New (DQ < 85)

83.33

51.52

41.02

2.56

Original

0

100

0

7.69

New (DQ < 85)

66.67

100

0

2.56

Original

20

100

0

10.26

New (DQ < 85)

80

94.12

5.13

2.56

Original

0

100

0

7.69

New (DQ < 85)

66.67

80.56

17.95

2.56

Original

9.17

100

0

9.61

New (DQ < 85)

74.17

81.55

16.03

2.56

Personal-Social

Language Fine motor Overall

Results: Step two Aim 1: Concurrent validity with ASQ • Calculated: - Sensitivity - Specificity - Over-referral rates - Under-referral rates

Results: Step two Aim 1: Concurrent validity with ASQ Development SGS scoring area

Sensitivity (%)

Specificity OverUnder(%) referrals (%) referrals (%)

Locomotor

10

98.81

1.06

9.57

New (DQ < 85) 70

92.86

6.38

3.19

Original

50

93.02

6.38

4.26

New (DQ < 85) 75

83.72

14.89

2.13

Original

26.67

92.41

6.38

11.70

New (DQ < 85) 66.67

77.22

19.15

5.32

Original

28.89

94.75

4.61

8.51

New (DQ < 85) 70.56

84.60

13.47

3.55

Language Fine motor Overall

Original

Discussion 1 • New SGS scoring method shows increased concurrent validity. • Better sensitivity, comparable specificity, higher over-referrals, lower under-referrals.

Discussion 2 Limitations • Small sample sizes • GMDS training Implications • Increased detection rates • Greater use in clinical practice and research

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