EARLY DETERMINANTS OF LUNG FUNCTION IN AFRICAN INFANTS D Gray 1 , L - - PowerPoint PPT Presentation

EARLY DETERMINANTS OF LUNG FUNCTION IN AFRICAN INFANTS

D Gray1, L Willemse1, A Visagie1, E Smith1, PD Sly2, GL Hall3, HJ Zar1

1Department of Paediatrics and Child Health, Red Cross War Memorial Children’s Hospital,

University of Cape Town, South Africa, 2Queensland Children's Medical Research Institute, University of Queensland, Brisbane, Australia 3Telethon Kids Institute, University of Western Australia, Perth, Australia

Disclosures

• None

Background

• Low lung function in

early life is a risk for respiratory illness

• High prevalence of

respiratory disease in African children

• No data on lung

function in African infants

Aim

To assess antenatal and early life factors associated with early lung function in infants enrolled in a South African birth cohort study

Methods: Drakenstein Child Health Study

• Multidisciplinary birth

cohort study

• Peri urban area, 60km
• utside Cape Town
• High burden of

childhood respiratory disease

Methods: Antenatal recruitment from two primary health care clinics

Mbekweni community (Ethnicity – African) Newman community (Ethnicity – Mixed)

• Questionnaires at schedules study visits
• Maternal smoking confirmed on antenatal urine cotinine

Infant lung function measures

• 6-10 weeks
• Natural quiet sleep
• Lung function tests:
• Tidal breathing

measures

• Exhaled nitric oxide
• SF6 Multiple breath

washout

• ATS/ERS testing guidelines

Results

552 infants tested

Specific TBFVL exclusions: Insufficient sleep: 7 Technical problem: 2 Poor quality: 1

Technically acceptable TBFVL 542 (98%)

Specific eNO exclusions: Insufficient sleep:: 7 Technical problem: 10 Poor quality: 2

Technically acceptable eNO 533 (97%)

Specific MBW exclusions: Insufficient sleep: 18 Technical problem: 11 Poor quality: 11

Technically acceptable MBW 512 (93%)

Demographics of infants by ethnicity/site

African ethnicity N = 260 Mixed ethnicity N = 292 Total med (IQR) N = 552 Age at test (weeks) 7.1 (6.4; 8.1) 7.2 (6.6;8.3) 7.3 (6.6; 8.1) Weight (kg) 4.9 (4.4; 5.5) 4.7 (4.2; 5.2) 4.8 (4.3; 5.4) Height (cm) 55 (53; 58) 55 (53; 57) 55 (53; 57) Birth weight (kg) 3.1 (2.8; 3.5) 3.0 (2.6; 3.4) 3.0 (2.7; 3.4) Gestation (weeks) 39 (38; 40) 39 (38; 40) 39 (38; 40) N (%) N (%) N (%) Male 117 (45) 166 (57) 283 (51) Preterm (<37 wk) 37 (14) 41 (14) 78 (14) Active smoker 39 (16) 145 (52) 185 (35) Maternal HIV 91 (35) 8 (3) 99 (18) Mbekweni site 257 (99) 2 (1) 259 (47) bold text: statistically significant p<0.05

Association of lung function at 6 -10 weeks and sex

Female Mean (SD) Male Mean (SD) Total Mean (SD) Multivariate linear regression P value* 95% CI Respiratory rate n.min-1 48.7 (12.3) 48.2 (11.7) 48.4 (12.0) 0.6

• 1.4 to 2.6

tPTEF/tE % 40.9 (12.2) 37.9 (12.7) 39.4 (12.5) 0.05

• 4.3 to -0.01

FRC mL 78.0 (17) 75.9 (15.8) 77.1 (16.4) 0.03

• 6.0 to -0.3

Exhaled NO 9.7 (6.6) 9.6 (6.7) 9.7 (6.6) 0.5

• 1.5 to 0.8

*Adjusted for weight, height, age, ethnicity, maternal smoking, maternal HIV status, previous pneumonia and prematurity

Association lung function at 6-10 weeks and maternal smoking during pregnancy

Maternal non- smoker Mean (SD) Maternal smoker Mean (SD) Total Mean (SD) Multivariate linear regression P value* 95% CI Respiratory rate .min-1 49.4 (12.1) 49.2 (11.9) 49.3 (12.0) 0.8

• 2.8 to 3.4

tPTEF/tE % 42.0 (11.7) 38.0 (12.4) 39.7 (12.2) 0.01

• 7.4 to -0.9

FRC mL 79.6 (16.8) 75.0 (14.8) 77.1 (15.8) 0.1

• 7.3 to 0.8

Exhaled NO 10.2 (6.7) 9.3 (5.7) 9.7 (6.2) 0.02

• 0.25 to -0.02

*Adjusted for weight, height, age, ethnicity, sex, maternal HIV status, previous pneumonia and prematurity

Association of lung function at 6 to 10 weeks and ethnicity/site

African ethnicity Mean (SD) Mixed ethnicity Mean (SD) Total Mean (SD) Multivariate linear regression P value* 95% CI Respiratory rate n.min-1 49.8 (12.2) 47.2 (11.6) 48.4 (12.0) <0.001 2.1 to 6.9 tPTEF/tE % 41.7 (11.8) 37.2 (12.8) 39.4 (12.5) 0.02 0.4 to 5.5 FRC mL 78.8 (17.3) 75.6 (15.4) 77.1 (16.4) 0.7

• 2.6 to 4.0

Exhaled NO 9.3 (6.9) 10.0 (6.4) 9.7 (6.6) 0.5

• 1.5 to 0.8

*Adjusted for weight, height, age, sex, maternal smoking, maternal HIV status, previous pneumonia and prematurity

Association infant lung function at 6 -10 weeks and maternal HIV infection

Mother HIV negative Mean (SD) Mother HIV positive Mean (SD) Total Mean (SD) Multivariate linear regression P value* 95% CI Respiratory rate n.min-1 50.6 (12.0) 48.6 (12.4) 49.9 (12.2) 0.1

• 6.0 to 0.7

tPTEF/tE % 40.9 (10.8) 43.4 (13.2) 41.7 (11.8) 0.06

• 0.1 to 6.6

FRC mL 78.0 (17.8) 79.9 (16.4) 78.6 (17.3) 0.1

• 1.2 to 8.6

Exhaled NO 9.0 (6.4) 10.0 (7.6) 9.3 (6.7) 0.2

• 0.6 to 3.2

*Adjusted for weight, height, age, sex, maternal smoking, maternal HIV status, previous pneumonia and prematurity

Conclusions

• Male infants have lower early lung function compared

to female infants.

• In utero smoke exposure is an important determinant of

decreased early lung function.

• The ethnic differences in lung function may be due to

gene-environment interactions.

• Maternal HIV infection was not associated with early

lung function outcomes.

• Antenatal and early life factors have a significant

impact on lung growth and function in early infancy, which may impact on risk for respiratory disease.

Acknowledgements

• Drakenstein study staff:
• Lauren Willemse, Ane Alberts, Des

Pietersen, Joavine Fourie

• Study participants
• Paarl Hospital for testing space
• Supervisors and collaborators
• Prof Heather Zar, Prof Graham Hall,

Prof Peter Sly

• Funders
• The Wellcome Trust
• Thrasher Foundation
• Bill and Melinda Gates Foundation
• Worldwide Universities Network,

University of Cape Town

Association lung function and maternal smoking during pregnancy – no exposure, passive exposure and active smoking

P=0.06 P=0.04