Initial validation of the Schedule of Growing Skills (SGS)

Margiad Elen WilliamsBangor 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 cut-off 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 comparisonsGriffiths 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

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%

Aim 1: Establishing cut-off point

Results: Step one

Aim 2: Concurrent validity with GMDS

• Calculated:- Sensitivity- Specificity- Over-referral rates- Under-referral rates

Results: Step oneAim 2: Concurrent validity with GMDS

Development area

SGS scoring Sensitivity (%)

Specificity (%)

Over-referrals (%)

Under-referrals (%)

Locomotor Original 16.67 100 0 12.80

New (DQ < 85) 83.33 51.52 41.02 2.56

Personal-Social

Original 0 100 0 7.69

New (DQ < 85) 66.67 100 0 2.56

Language Original 20 100 0 10.26

New (DQ < 85) 80 94.12 5.13 2.56

Fine motor Original 0 100 0 7.69

New (DQ < 85) 66.67 80.56 17.95 2.56

Overall Original 9.17 100 0 9.61

New (DQ < 85) 74.17 81.55 16.03 2.56

Results: Step two

Aim 1: Concurrent validity with ASQ

• Calculated:- Sensitivity- Specificity- Over-referral rates- Under-referral rates

Results: Step twoAim 1: Concurrent validity with ASQ

Development area

SGS scoring Sensitivity (%)

Specificity (%)

Over-referrals (%)

Under-referrals (%)

Locomotor Original 10 98.81 1.06 9.57

New (DQ < 85) 70 92.86 6.38 3.19

Language Original 50 93.02 6.38 4.26

New (DQ < 85) 75 83.72 14.89 2.13

Fine motor Original 26.67 92.41 6.38 11.70

New (DQ < 85) 66.67 77.22 19.15 5.32

Overall Original 28.89 94.75 4.61 8.51

New (DQ < 85) 70.56 84.60 13.47 3.55

Discussion 1

• New SGS scoring method shows increased concurrent validity.

• Better sensitivity, comparable specificity, higher over-referrals, lower under-referrals.

Limitations• Small sample sizes• GMDS training

Implications• Increased detection rates• Greater use in clinical practice and research

Discussion 2

Thank you for listening

Diolch am wrando

Any questions??