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Flexible assessment of trends in age‐specific HIV incidence using two‐dimensional penalized likelihood
Author(s) -
Marschner Ian C.,
Bosch Ronald J.
Publication year - 1998
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/(sici)1097-0258(19980515)17:9<1017::aid-sim787>3.0.co;2-g
Subject(s) - incidence (geometry) , smoothing , bivariate analysis , statistics , computer science , mathematics , econometrics , demography , sociology , geometry
We present a method for estimating age‐ and time‐specific HIV incidence using back‐calculation of AIDS incidence data. Two‐dimensional penalized likelihood is employed, using a flexible bivariate step function model of HIV incidence, together with a quadratic roughness penalty which leads to thin‐plate spline smoothing. This allows incidence estimates to vary flexibly and smoothly in both age and time. We propose generalized cross‐validation as a guide for choice of an appropriate level of smoothing and describe an EM algorithm for computing the estimates. We propose the method primarily for qualitative assessment of trends in age‐specific incidence over time and apply it to a small Italian data set on men who have sex with men. The analysis suggests a trend over time of increasing relative incidence among younger individuals, consistent with incidence patterns observed in other countries. © 1998 John Wiley & Sons, Ltd.