Influence of life course income trajectories on oral health outcomes: findings from the 1993 Pelotas, Brazil, birth cohort study
METHODS: Data from a population-based birth cohort study started in 1993 in Pelotas, Brazil was used. Family income was assessed at birth, childhood, adolescence, and in adulthood. Outcomes were gingival bleeding (GB) in adolescents (n=339) and increment of dental caries from childhood to young adulthood (n=302). A latent class growth analysis was conducted to identify family income trajectories. Well-known confounders were taken into account in the multivariable models.
RESULTS: Adjusted analyses showed adolescents who were always poor presented a 53% higher average of GB than those who were never poor. Poverty at birth increased rates of adolescents’ gingival bleeding by 24% regardless of current family income. After adjusting for mother’s education level and toothbrushing frequency, the number of decayed (D) and filled (F) tooth increase over year 6 to year 18 were significantly associated with family income trajectory and dental caries index (DMFT) at age 6. The incident rate ratios (RR) of D compared to the group of stable high-incomes was 2.53 (95% CI 1.60 - 4.03) for stable low-incomes, 1.86 (95% CI 0.99 -3.48) for downward, 1.71 (95% CI 0.99 – 2.95) for upward respectively. The RR of F with stable low incomes group compared to stable high incomes was 0.56 (95% CI 0.36 – 0.87).
CONCLUSIONS: Family income mobility may have impact on dental outcomes during lifetime.