Multivariable flexible modelling for estimating complete, smoothed life tables for sub-national populations

BMC Public Health. 2015 Dec 16;15:1240. doi: 10.1186/s12889-015-2534-3.

Abstract

Background: The methods currently available to estimate age- and sex-specific mortality rates for sub-populations are subject to a number of important limitations. We propose two alternative multivariable approaches: a relational model and a Poisson model both using restricted cubic splines.

Methods: We evaluated a flexible Poisson and flexible relational model against the Elandt-Johnson approach in a simulation study using 100 random samples of population and death counts, with different sampling proportions and data arrangements. Estimated rates were compared to the original mortality rates using goodness-of-fit measures and life expectancy. We further investigated an approach for determining optimal knot locations in the Poisson model.

Results: The flexible Poisson model outperformed the flexible relational and Elandt-Johnson methods with the smallest sample of data (1%). With the largest sample of data (20%), the flexible Poisson and flexible relational models performed comparably, though the flexible Poisson model displayed a slight advantage. Both approaches tended to underestimate infant mortality and thereby overestimate life expectancy at birth. The flexible Poisson model performed much better at young ages when knots were fixed a priori. For ages 30 and above, results were similar to the model with no fixed knots.

Conclusions: The flexible Poisson model is recommended because it derives robust and unbiased estimates for sub-populations without making strong assumptions about age-specific mortality profiles. Fixing knots a priori in the final model greatly improves fit at the young ages.

Keywords: Cubic splines; Deprivation; Generalised linear model; Life expectancy; Life tables; Model life tables; Mortality rates; Small areas.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Child
  • Child, Preschool
  • England / epidemiology
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Life Expectancy*
  • Life Tables*
  • Male
  • Middle Aged
  • Models, Statistical*
  • Multivariate Analysis
  • Poisson Distribution
  • Young Adult