Is population structure sufficient to generate area-level inequalities in influenza rates An examination using agent-based modelsReport as inadecuate




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BMC Public Health

, 15:947

First Online: 23 September 2015Received: 23 May 2015Accepted: 15 September 2015DOI: 10.1186-s12889-015-2284-2

Cite this article as: Kumar, S., Piper, K., Galloway, D.D. et al. BMC Public Health 2015 15: 947. doi:10.1186-s12889-015-2284-2

Abstract

BackgroundIn New Haven County, CT NHC, influenza hospitalization rates have been shown to increase with census tract poverty in multiple influenza seasons. Though multiple factors have been hypothesized to cause these inequalities, including population structure, differential vaccine uptake, and differential access to healthcare, the impact of each in generating observed inequalities remains unknown. We can design interventions targeting factors with the greatest explanatory power if we quantify the proportion of observed inequalities that hypothesized factors are able to generate. Here, we ask if population structure is sufficient to generate the observed area-level inequalities in NHC. To our knowledge, this is the first use of simulation models to examine the causes of differential poverty-related influenza rates.

MethodsUsing agent-based models with a census-informed, realistic representation of household size, age-structure, population density in NHC census tracts, and contact rates in workplaces, schools, households, and neighborhoods, we measured poverty-related differential influenza attack rates over the course of an epidemic with a 23 % overall clinical attack rate. We examined the role of asthma prevalence rates as well as individual contact rates and infection susceptibility in generating observed area-level influenza inequalities.

ResultsSimulated attack rates AR among adults increased with census tract poverty level F = 30.5; P < 0.001 in an epidemic caused by a virus similar to A H1N1 pdm09. We detected a steeper, earlier influenza rate increase in high-poverty census tracts—a finding that we corroborate with a temporal analysis of NHC surveillance data during the 2009 H1N1 pandemic. The ratio of the simulated adult AR in the highest- to lowest-poverty tracts was 33 % of the ratio observed in surveillance data. Increasing individual contact rates in the neighborhood did not increase simulated area-level inequalities. When we modified individual susceptibility such that it was inversely proportional to household income, inequalities in AR between high- and low-poverty census tracts were comparable to those observed in reality.

DiscussionTo our knowledge, this is the first study to use simulations to probe the causes of observed inequalities in influenza disease patterns. Knowledge of the causes and their relative explanatory power will allow us to design interventions that have the greatest impact on reducing inequalities.

ConclusionDifferential exposure due to population structure in our realistic simulation model explains a third of the observed inequality. Differential susceptibility to disease due to prevailing chronic conditions, vaccine uptake, and smoking should be considered in future models in order to quantify the role of additional factors in generating influenza inequalities.

KeywordsAgent-based model Influenza inequalities Area-level inequalities Census tracts Poverty AbbreviationsARSIMSimulated attack rates

AREIPObserved attack rates in surveillance by the Emerging Infections Program

CT-EIPConnecticut Emerging Infections Program

RRSIMRate ratio of attack rates from the simulation

RREIPRate ratio of attack rates from observed Emerging Infections Program data

NHCNew Haven County, CT

SESSocio-economic status

ACSAmerican community survey

Electronic supplementary materialThe online version of this article doi:10.1186-s12889-015-2284-2 contains supplementary material, which is available to authorized users.

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Author: Supriya Kumar - Kaitlin Piper - David D. Galloway - James L. Hadler - John J. Grefenstette

Source: https://link.springer.com/







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