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Computational and Mathematical Methods in Medicine
Volume 2017, Article ID 7518035, 16 pages
Research Article

Estimating and Interpreting Effects from Nonlinear Exposure-Response Curves in Occupational Cohorts Using Truncated Power Basis Expansions and Penalized Splines

1Department of Mathematics and Statistics, American University, Washington, DC, USA
2Occupational Science & Technology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA

Correspondence should be addressed to Elizabeth J. Malloy; ude.nacirema@yollam

Received 31 January 2017; Revised 25 April 2017; Accepted 16 May 2017; Published 20 September 2017

Academic Editor: Ruisheng Wang

Copyright © 2017 Elizabeth J. Malloy et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Truncated power basis expansions and penalized spline methods are demonstrated for estimating nonlinear exposure-response relationships in the Cox proportional hazards model. R code is provided for fitting models to get point and interval estimates. The method is illustrated using a simulated data set under a known exposure-response relationship and in a data application examining risk of carpal tunnel syndrome in an occupational cohort.