Latent Class Analysis of the Breadth, Severity and Stability of Child Health

Inequalities Mensah FK, Nicholson JM, Headley L, Carlin JB, Berthelsen D, Wake M

NHMRC Capacity Building Grant, MCRI, RCH and University of MelbourneProfessors Melissa Wake, John Carlin Professor Jan Nicholson, Parenting Research Centre, MelbourneLiz Headley, Victorian Public Health Training Scheme and Monash UniversityProfessor Donna Berthelsen, Queensland University of Technology

Gender Equality Network, Economic and Social Research Council UKDr Wendy Sigle-Rushton, London School of EconomicsProfessors John Hobcraft and Kathleen Kiernan, Department of Social Policy and Social Work and Institute of Effective Education, University of York

Acknowledgments

Multiple Outcomes of Health Inequality

Models have often focused on single outcomes– fail to consider breadth of impact and address “multifinality”

Alternative strategies– summary indices– multiple outcome models

Example to follow: Impact of socioeconomic position on children’s risks for multiple problems in physical, socio-emotional and cognitive functioning

Two national cohorts of ~5,000 children each

Infants (0-1 yrs) & Kindergarten children (4-5 yrs) in 2004

Followed up every two years

Conducted by Australian Govt. Department of Families, Housing, Community Services and Indigenous Affairs (FaHCSIA), Australian Institute of Family Studies (AIFS), and the Australian Bureau of Statistics (ABS) with advice from a national research consortium

www.aifs.gov.au/growingup/

The Longitudinal Study of Australian Children (LSAC)

Most advan-taged

qu. 2 qu. 3 qu. 4 Least advan-taged

0

25

50

75

33.1

64.3

9.2

32.6

at least one problem in 2 or more domains at least one problem in all 3 domains

%

Physical, Psychosocial and Cognitive Difficulties at 4-5 (Birth cohort)

Latent Class Analysis (LCA)

• Groups children to reflect key differences

• Accounts for inter-correlations between measures

• Similar to cluster analysis, but is model based (probabilistic)

• Gives model fit statistics to determine number of categories

• Uses specialist software such as Mplus

E.g. Multiple problem behaviours in adolescence

Fergusson et al. 1994, Journal of Child Psychology & Psychiatry 35 (6) 1123-1140

Subtypes and severity of peer victimisation

Nylund et al. 2007, Child Development 78 (6) 1706-1722

Study designAge 4-5 Age 6-7 Age 8-9

K cohort (wave 1) (N=3,711) K cohort (wave 2) (N=2,563) K cohort (wave 3) (N=3,080)

B cohort (wave 3) (N=3,608)(replication sample)

Indicators and Measures

Global health measure Excellent / Very good / Good / Fair or Poor

Special health care needs No / Yes (condition lasting for at least 12 months requiring medicines, medical care, health or educational services )

Asthma diagnosis No / Yes

Sleep difficulties 0,1,2+ (getting to sleep, sleeping alone, waking during the night)

Injuries 0,1,2+ in the last year

Body mass index Underweight / Normal / Overweight / Obese

Peds Quality of Life Physical, Social, Emotional and School Scores

Strengths and Difficulties Pro-social, Conduct, Emotional, Hyperactivity and Peers Scores

Peabody Picture vocabulary test Direct Assessment of Language Development

Who am I? (Age 4-5) Direct Assessment of School Readiness

Teacher rating scales (Age 6-7, 8-9) Language and Literacy, Mathematical Thinking

Model fit parameters (K cohort age 4-5)

266,000

268,000

270,000

272,000

274,000

276,000

278,000

1 2 3 4 5 6Number of classes

Akaike information criteria (AIC)

Bayesian information criteria (BIC)

Adjusted BIC

P value 0.000 0.014 0.048 0.188 0.327

Classes 0.750.25

0.590.330.07

0.550.200.190.07

0.450.220.200.090.05

0.380.220.150.120.090.04

Mean score for Healthiest(59.5%)

Moderate(33.4%)

Severe(7.2%)

Peds Quality of Life: Physical 87.1 79.8 63.0

Social 90.3 77.4 52.1

Emotional 78.5 64.4 56.8

School 93.3 83.8 58.2

Strengths and difficulties Pro-social 8.3 7.0 6.8

Conduct difficulties 1.7 3.7 3.6

Emotional difficulties 1.1 2.3 3.7

Hyperactivity 2.7 4.6 5.0

Difficulties With Peers 1.1 2.2 3.2

Language PPVT 65.0 63.6 59.7

School readiness Who am I 65.2 63.4 61.1

Profiles from 3 class model (K cohort age 4-5)

Percent of children with Healthiest(59.5%)

Moderate(33.4%)

Severe(7.2%)

Fair or poor health 1.0 3.1 9.3

Special health care need 7.2 17.2 38.6

Asthma diagnosis 16.9 26.5 34.0

2 or more sleep problems 7.1 21.3 23.3

2 or more injuries 2.8 6.3 6.9

Underweight 4.9 5.0 7.0

Overweight/obese 19.3 20.4 21.1

Profiles from 3 class model (K cohort age 4-5)

Replication and consistency of 3 class structure

B cohort K cohort

Age 4-5 (%) Age 4-5 (%) Age 6-7 (%) Age 8-9 (%)

(N=3,608) (N=3,711) (N=2,563) (N=3,080)

Healthiest 54.7 59.2 60.3 54.9

Moderate 38.4 33.4 30.5 36.5

Severe 6.9 7.4 9.2 8.6

Common sample across 3 waves of the K cohort N=1,685

Age 4-5 (%) Age 6-7 (%) Age 8-9 (%)

Healthiest 64.7 64.2 60.0

Moderate 30.1 29.0 33.5

Severe 5.2 6.7 6.6

Classification (K cohort age 4-5)

ESTIMATED CLASS PROPORTIONS AND COUNTS

CLASSIFICATION QUALITY (Entropy) 0.809

CLASSIFICATION OF INDIVIDUALS BASED ON THEIR MOST LIKELY LATENT CLASS MEMBERSHIP

1 (Healthiest) 0.592 2196

2 (Moderate) 0.334 1241

3 (Severe) 0.074 274

1 (Healthiest) 0.595 2208

2 (Moderate) 0.334 1238

3 (Severe) 0.072 265

A further technique for classification after LCA

Technique of random draws on the basis of probabilities

http://www.statmodel.com/download/meantest2.pdf

Takes into account both bias and uncertainty

Similar principles to multiple imputation

Implemented in Mplus as a default

Can also be implemented in Stata

Feeds into descriptive analysis and regression models

Girls

Most advantaged

2nd Quintile

3rd Quintile

4th Quintile

Least advantaged

Boys

Most advantaged

2nd Quintile

3rd Quintile

4th Quintile

Least advantaged

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Moderate

Severe

Proportion of children

Health Inequalities - K cohort age 4-5

Most healthy (%)

Moderate (%)

Severe (%)

69.5 27.7 2.8

69.2 27.7 3.1

69.3 24.4 6.3

56.6 36.2 7.2

47.5 37.9 14.6

61.2 33.0 5.9

63.0 31.3 5.6

56.7 36.6 6.7

54.0 39.2 6.9

39.4 43.4 17.2

Stability through childhood (K cohort)

Age 6-7 Age 8-9Healthiest (%)

Moderate (%)

Severe (%)

Healthiest (%)

Moderate (%)

Severe (%)

Age 4-5 Healthiest 78.8 18.5 2.8 73.0 25.5 1.5

Moderate 41.2 50.1 8.7 39.6 48.6 11.8

Severe 16.5 38.9 44.6 15.7 45.3 39.0

Age 6-7 Healthiest 77.7 22.0 0.3

Moderate 31.1 55.7 13.3

Severe 15.5 47.3 37.2

Conclusions, continuation and discussion

Clear and reproducible groups reflecting degree of difficulties

Powerful social grading

Strong continuity from early to mid-childhood

Potential to examine predictors, prognosis and associated costs

For discussion:

Criteria for evaluating validity

Utility of this type of indicator beyond academic research