Lung Function Trajectories From Birth to 6 Years in an African Birth Cohort

05 Mar 20264 min read0 viewsJournal Feed

GIST

In this African birth cohort study, lung function trajectories were tracked from birth to 6 years using intra-breath oscillometry to quantify end-expiratory impedance components. Six measurement points (6 weeks to 6 years) enabled joint modelling of end-expiratory resistance and reactance, yielding five distinct respiratory-system-impedance trajectories: normal (70.2%), persistent low (2.4%), early normal with decline (8.4%), early low with catch-up (5.8%), and decline with recovery (13.1%).

Overall, 11% (90/830) exhibited low trajectories (persistent low or early normal with decline) through age 6. Early-life factors associated with adverse trajectories included respiratory syncytial virus lower respiratory tract infection, prematurity, and postnatal maternal psychological distress.

Conversely, about 19% (157) demonstrated catch-up to normal function by age 6, via early low with catch-up or decline and recovery trajectories. At 6 years, spirometric indices varied by trajectory, with the normal group showing the highest FEV1 and FVC, and the persistent low group the lowest.

The study notes uncertainty remains regarding the full causal impact of modifiable factors and the extent to which these trajectories reflect true lung development versus measurement or population-specific effects.

Clinical Editorial

Study design and population

Prospective birth cohort study conducted in Drakenstein, Africa, following children from birth to 6 years.
Lung function assessed at six time points from 6 weeks to 6 years using intra-breath oscillometry to quantify end-expiratory impedance components.
Comprehensive exposure data collected longitudinally from the antenatal period through childhood.
Analysis employed group-based multi-trajectory modelling to jointly characterize end-expiratory resistance and end-expiratory reactance trajectories.

Key findings on trajectory structure

Five distinct respiratory impedance trajectories emerged as the optimal representation of the data.
Normal: the majority (70.2%).
Persistent low: a small subset (2.4%).
Early normal with subsequent decline: 8.4%.
Early low with catch-up: 5.8%.
Decline with recovery: 13.1%.
Overall, 11% of children (90/830) exhibited low trajectories (persistent low or early normal with decline).
A substantial portion (19%, 157/830) showed catch-up to normal function by age 6 (either early low with catch-up or decline with recovery).

Determinants and associations

Risk factors linked to adverse trajectory patterns included respiratory syncytial virus-associated lower respiratory tract infection, preterm birth, and postnatal maternal psychological distress.
By age 6, spirometric indices varied by trajectory, with the normal-trajectory group achieving higher FEV1 and FVC, while the persistent low-trajectory group displayed the lowest measures.

Context and implications

The data illuminate early-life lung function trajectories through infancy and preschool years, highlighting trajectories that may support healthy development and those associated with persistent impairment.
Modifiable factors, notably prematurity, RSV-LRTI, and maternal psychological distress, were associated with less favorable trajectories.

Limitations and transparency

The study is observational and limited to a single African birth cohort; causal inferences should be drawn cautiously.
Based on oscillometry-derived impedance rather than standard spirometric metrics at all time points; some findings rely on trajectory modeling assumptions.
Not all potential confounders or longer-term outcomes beyond 6 years are detailed in the available content.