Late-life disability trajectories in Yoruba Nigerians and the Spanish population: a state space model in continuous time.

OBJECTIVES

We compared the trajectory of activities of daily living (ADL) in a nationally representative sample of older Nigerians with their Spanish peers and identified factors to explain country-specific growth models.

METHODS

Data from two household multistage probability samples were used, comprising older adults from Spain (n = 2,011) and Nigeria (n = 1,704). All participants underwent assessment for ADL. Risk factors including sex, household income, urbanicity, years of education, depression, alcohol consumption and smoking were assessed using validated methods. State-space model in continuous time (SSM-CT) methods were used for trajectory comparison.

RESULTS

Compared with Nigerians (µADL80=0.44, SE = 0.015, p < 0.001), Spanish older adults had higher disability scores (µADL80=1.23, SE = 0.021, p < 0.001). In SSM-CT models, the rate of increase in disability was faster in Nigerians (Nigeria: β = 0.061, p<.01; Spain: β = 0.028, p < 0.010). An increasing course of disability in the Spanish sample was predicted by female sex, lower education and depression diagnosis.

CONCLUSION

The rate of increase in disability was faster in older Nigerians living in an economically disadvantaged context.