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

• Published in: BMC public health Vol. 15; no. 10840; p. 1240
• Main Authors: Rachet, Bernard, Maringe, Camille, Woods, Laura M, Ellis, Libby, Spika, Devon, Allemani, Claudia
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 16.12.2015; BioMed Central
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Analysis; Birth rates; Child; Child, Preschool; England - epidemiology; Female; Humans; Infant; Infant, Newborn; Life Expectancy; Life Tables; Male; Middle Aged; Models, Statistical; Multivariate Analysis; Poisson Distribution; Social classes; Technical Advance; Young Adult; United Kingdom; Deprivation; Life expectancy; Life tables; Generalised linear model; Mortality rates; Small areas; Cubic splines; Model life tables
• ISSN: 1471-2458; 1471-2458
• DOI: 10.1186/s12889-015-2534-3

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. 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. 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. 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.