Changes in asset-based wealth across the life course in birth cohorts from five low- and middle-income countries

Background

Temporally-harmonized asset-based measures of wealth can be used to study the association of life-course wealth exposures in the same scale with health outcomes in low- and middle-income countries (LMICs). The within-individual longitudinal stability of asset-based indices of wealth in LMICs is poorly understood.

Methods

Using data from five birth cohorts from three continents, we developed temporally-harmonized asset indices over the life course through polychoric principal component analysis of a common set of assets collected consistently over time (18 years in Brazil to 50 years in Guatemala). For each cohort, we compared the harmonized index to cross-sectional indices created using more comprehensive asset measures using rank correlations. We evaluated the rank correlation of the harmonized index in early life and adulthood with maternal schooling and own attained schooling, respectively.

Results

Temporally-harmonized asset indices developed from a consistently-collected set of assets (range: 10 in South Africa to 30 in Philippines) suggested that mean wealth improved over time for all birth cohorts. Cross-sectional indices created separately for each study wave were correlated with the harmonized index for all cohorts (Brazil: r = 0.78 to 0.96; Guatemala: r = 0.81 to 0.95; India: 0.75 to 0.93; Philippines: r = 0.92 to 0.99; South Africa: r = 0.84 to 0.96). Maternal schooling (r = 0.15 to 0.56) and attained schooling (r = 0.23 to 0.53) were positively correlated with the harmonized asset index in childhood and adulthood respectively.

Conclusions

Temporally-harmonized asset indices displayed coherence with cross-sectional indices as well as construct validity with schooling.

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Temporally-harmonized asset indices are useful to assess relative importance of wealth at different life stages with health on the same scale.

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Harmonized indices using a subset of assets were correlated with cross-sectional asset indices using all available assets in five LMIC birth cohorts.

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Harmonized indices displayed construct validity, as demonstrated by its correlation with schooling.

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Harmonized indices were robust to alternate specifications such as shorter lists of assets, study years, and factor extraction procedures.

Relative and absolute wealth mobility since birth in relation to health and human capital in middle adulthood: An analysis of a Guatemalan birth cohort

Background

Wealth mobility, as both relative (positional) and absolute (material) wealth acquisition, may counteract negative consequences of early life adversities on adult health.

Methods

We use longitudinal data (1967–2018) from the INCAP birth cohort, Guatemala (n = 1386). Using wealth as a measure of socio-economic position, we assess the association of life course relative mobility using latent class analysis and absolute material gains using conditional wealth measures. We estimate associations of wealth mobility with indicators of human capital, specifically height, weight status (BMI in kg/m²), psychological distress (WHO SRQ-20 score) and fluid intelligence (Ravens Progressive Matrices score; RPM) in middle adulthood.

Results

We identified four latent classes of relative mobility – Stable Low (n = 498), Stable High (n = 223), Downwardly Mobile (n = 201) and Upwardly Mobile (n = 464). Attained schooling (years) was positively associated with membership in Upwardly Mobile (odds ratio; 1.50, 95%CI: 1.31, 1.71) vs Stable Low, and inversely with membership in Downwardly Mobile (0.65, 95%CI: 0.54, 0.79) vs Stable High. Being Upwardly Mobile (vs Stable Low) was positively associated with height (1.88 cm, 95%CI: 1.04, 2.72), relative weight (1.32 kg/m², 95%CI: 0.57, 2.07), lower psychological distress (−0.82 units, 95%CI: 1.34, −0.29) and fluid intelligence (0.94 units, 95%CI: 0.28, 1.59). Being Downwardly Mobile (vs Stable High) was associated with lower fluid intelligence (−2.69 units, 95%CI: 3.69, −1.68), and higher psychological distress (1.15 units, 95%CI: 0.34, 1.95). Absolute wealth gains (z-scores) from early to middle adulthood were positively associated with relative weight (0.62 kg/m², 95%CI: 0.28, 0.96), lower psychological distress (−0.37 units, 95%CI: 0.60, −0.14) and fluid intelligence (0.50 units, 95%CI: 0.21, 0.79).

Conclusions

Higher attained schooling provided a pathway for upward relative mobility and higher absolute wealth gains as well as protection against downward relative mobility. Upward mobility was associated with lower psychological distress and higher fluid intelligence but also higher weight status.

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Early life wealth and educational attainment are associated with upward wealth mobility, both in relative and absolute terms.

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Upward relative mobility is associated with lower psychological distress, and higher fluid intelligence and BMI.

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Downward relative mobility is associated with lower fluid intelligence, lower height, and higher psychological distress.

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Wealth gains from early to middle adulthood were associated with higher BMI and intelligence and lower psychological distress.