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Keller JP, Drton M, Larson T, Kaufman JD, Sandler DP, Szpiro AA. COVARIATE-ADAPTIVE CLUSTERING OF EXPOSURES FOR AIR POLLUTION EPIDEMIOLOGY COHORTS. Ann Appl Stat 2017; 11:93-113. [PMID: 28572869 PMCID: PMC5448716 DOI: 10.1214/16-aoas992] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cohort studies in air pollution epidemiology aim to establish associations between health outcomes and air pollution exposures. Statistical analysis of such associations is complicated by the multivariate nature of the pollutant exposure data as well as the spatial misalignment that arises from the fact that exposure data are collected at regulatory monitoring network locations distinct from cohort locations. We present a novel clustering approach for addressing this challenge. Specifically, we present a method that uses geographic covariate information to cluster multi-pollutant observations and predict cluster membership at cohort locations. Our predictive k-means procedure identifies centers using a mixture model and is followed by multi-class spatial prediction. In simulations, we demonstrate that predictive k-means can reduce misclassification error by over 50% compared to ordinary k-means, with minimal loss in cluster representativeness. The improved prediction accuracy results in large gains of 30% or more in power for detecting effect modification by cluster in a simulated health analysis. In an analysis of the NIEHS Sister Study cohort using predictive k-means, we find that the association between systolic blood pressure (SBP) and long-term fine particulate matter (PM2.5) exposure varies significantly between different clusters of PM2.5 component profiles. Our cluster-based analysis shows that for subjects assigned to a cluster located in the Midwestern U.S., a 10 μg/m3 difference in exposure is associated with 4.37 mmHg (95% CI, 2.38, 6.35) higher SBP.
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Affiliation(s)
- Joshua P Keller
- Department of Biostatistics, University of Washington, Box 357232, Health Sciences Building, F-600 1705 NE Pacific Street Seattle, WA 98195
| | - Mathias Drton
- Department of Statistics University of Washington, Box 354322, Seattle, WA 98195
| | - Timothy Larson
- Department of Civil and Environmental Engineering, University of Washington, Box 352700, 201 More Hall Seattle, WA 98195
| | - Joel D Kaufman
- Department of Environmental and Occupational Health Sciences, University of Washington, Box 354695, 4225 Roosevelt Way NE Seattle, WA 98105
| | - Dale P Sandler
- Epidemiology Branch National Institute of Environmental Health Sciences, P.O. Box 12233, Mail Drop A3-05 111 T W Alexander Dr Research Triangle Park, NC 27709
| | - Adam A Szpiro
- Department of Biostatistics, University of Washington, Box 357232, Health Sciences Building, F-600 1705 NE Pacific Street Seattle, WA 98195
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Kaufman JD, Spalt EW, Curl CL, Hajat A, Jones MR, Kim SY, Vedal S, Szpiro AA, Gassett A, Sheppard L, Daviglus ML, Adar SD. Advances in Understanding Air Pollution and CVD. Glob Heart 2016; 11:343-352. [PMID: 27741981 PMCID: PMC5082281 DOI: 10.1016/j.gheart.2016.07.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 07/13/2016] [Accepted: 07/21/2016] [Indexed: 12/21/2022] Open
Abstract
The MESA Air (Multi-Ethnic Study of Atherosclerosis and Air Pollution) leveraged the platform of the MESA cohort into a prospective longitudinal study of relationships between air pollution and cardiovascular health. MESA Air researchers developed fine-scale, state-of-the-art air pollution exposure models for the MESA Air communities, creating individual exposure estimates for each participant. These models combine cohort-specific exposure monitoring, existing monitoring systems, and an extensive database of geographic and meteorological information. Together with extensive phenotyping in MESA-and adding participants and health measurements to the cohort-MESA Air investigated environmental exposures on a wide range of outcomes. Advances by the MESA Air team included not only a new approach to exposure modeling, but also biostatistical advances in addressing exposure measurement error and temporal confounding. The MESA Air study advanced our understanding of the impact of air pollutants on cardiovascular disease and provided a research platform for advances in environmental epidemiology.
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Affiliation(s)
- Joel D Kaufman
- Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA; Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA; Department of Medicine, University of Washington, Seattle, WA, USA.
| | - Elizabeth W Spalt
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
| | - Cynthia L Curl
- Department of Community and Environmental Health, College of Health Sciences, Boise State University, Boise, ID, USA
| | - Anjum Hajat
- Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA
| | - Miranda R Jones
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Sun-Young Kim
- Institute of Health and Environment, Seoul National University, Seoul, Korea
| | - Sverre Vedal
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
| | - Adam A Szpiro
- Department of Biostatistics, University of Washington, Seattle, WA, USA
| | - Amanda Gassett
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
| | - Lianne Sheppard
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA; Department of Biostatistics, University of Washington, Seattle, WA, USA
| | - Martha L Daviglus
- Institute for Minority Health Research, University of Illinois at Chicago, Chicago, IL, USA; Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Sara D Adar
- Department of Epidemiology, University of Michigan, Ann Arbor, MI, USA
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Nicolis O, Mateu J. Discussion of the paper “analysis of spatio-temporal mobile phone data: a case study in the metropolitan area of Milan”. STAT METHOD APPL-GER 2015. [DOI: 10.1007/s10260-015-0311-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Olives C, Sheppard L, Lindström J, Sampson PD, Kaufman JD, Szpiro AA. Reduced-Rank Spatio-Temporal Modeling of Air Pollution Concentrations in the Multi-Ethnic Study of Atherosclerosis and Air Pollution. Ann Appl Stat 2014; 8:2509-2537. [PMID: 27014398 DOI: 10.1214/14-aoas786] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There is growing evidence in the epidemiologic literature of the relationship between air pollution and adverse health outcomes. Prediction of individual air pollution exposure in the Environmental Protection Agency (EPA) funded Multi-Ethnic Study of Atheroscelerosis and Air Pollution (MESA Air) study relies on a flexible spatio-temporal prediction model that integrates land-use regression with kriging to account for spatial dependence in pollutant concentrations. Temporal variability is captured using temporal trends estimated via modified singular value decomposition and temporally varying spatial residuals. This model utilizes monitoring data from existing regulatory networks and supplementary MESA Air monitoring data to predict concentrations for individual cohort members. In general, spatio-temporal models are limited in their efficacy for large data sets due to computational intractability. We develop reduced-rank versions of the MESA Air spatio-temporal model. To do so, we apply low-rank kriging to account for spatial variation in the mean process and discuss the limitations of this approach. As an alternative, we represent spatial variation using thin plate regression splines. We compare the performance of the outlined models using EPA and MESA Air monitoring data for predicting concentrations of oxides of nitrogen (NO x )-a pollutant of primary interest in MESA Air-in the Los Angeles metropolitan area via cross-validated R2. Our findings suggest that use of reduced-rank models can improve computational efficiency in certain cases. Low-rank kriging and thin plate regression splines were competitive across the formulations considered, although TPRS appeared to be more robust in some settings.
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