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Google Flu Trends Spatial Variability Validated Against Emergency Department Influenza-Related Visits.
J Med Internet Res. 2016 06 28; 18(6):e175.JM

Abstract

BACKGROUND

Influenza is a deadly and costly public health problem. Variations in its seasonal patterns cause dangerous surges in emergency department (ED) patient volume. Google Flu Trends (GFT) can provide faster influenza surveillance information than traditional CDC methods, potentially leading to improved public health preparedness. GFT has been found to correlate well with reported influenza and to improve influenza prediction models. However, previous validation studies have focused on isolated clinical locations.

OBJECTIVE

The purpose of the study was to measure GFT surveillance effectiveness by correlating GFT with influenza-related ED visits in 19 US cities across seven influenza seasons, and to explore which city characteristics lead to better or worse GFT effectiveness.

METHODS

Using Healthcare Cost and Utilization Project data, we collected weekly counts of ED visits for all patients with diagnosis (International Statistical Classification of Diseases 9) codes for influenza-related visits from 2005-2011 in 19 different US cities. We measured the correlation between weekly volume of GFT searches and influenza-related ED visits (ie, GFT ED surveillance effectiveness) per city. We evaluated the relationship between 15 publically available city indicators (11 sociodemographic, two health care utilization, and two climate) and GFT surveillance effectiveness using univariate linear regression.

RESULTS

Correlation between city-level GFT and influenza-related ED visits had a median of .84, ranging from .67 to .93 across 19 cities. Temporal variability was observed, with median correlation ranging from .78 in 2009 to .94 in 2005. City indicators significantly associated (P<.10) with improved GFT surveillance include higher proportion of female population, higher proportion with Medicare coverage, higher ED visits per capita, and lower socioeconomic status.

CONCLUSIONS

GFT is strongly correlated with ED influenza-related visits at the city level, but unexplained variation over geographic location and time limits its utility as standalone surveillance. GFT is likely most useful as an early signal used in conjunction with other more comprehensive surveillance techniques. City indicators associated with improved GFT surveillance provide some insight into the variability of GFT effectiveness. For example, populations with lower socioeconomic status may have a greater tendency to initially turn to the Internet for health questions, thus leading to increased GFT effectiveness. GFT has the potential to provide valuable information to ED providers for patient care and to administrators for ED surge preparedness.

Authors+Show Affiliations

Johns Hopkins University, School of Medicine, Hampstead, NC, United States. jjklem@gmail.com.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Validation Study

Language

eng

PubMed ID

27354313

Citation

Klembczyk, Joseph Jeffrey, et al. "Google Flu Trends Spatial Variability Validated Against Emergency Department Influenza-Related Visits." Journal of Medical Internet Research, vol. 18, no. 6, 2016, pp. e175.
Klembczyk JJ, Jalalpour M, Levin S, et al. Google Flu Trends Spatial Variability Validated Against Emergency Department Influenza-Related Visits. J Med Internet Res. 2016;18(6):e175.
Klembczyk, J. J., Jalalpour, M., Levin, S., Washington, R. E., Pines, J. M., Rothman, R. E., & Dugas, A. F. (2016). Google Flu Trends Spatial Variability Validated Against Emergency Department Influenza-Related Visits. Journal of Medical Internet Research, 18(6), e175. https://doi.org/10.2196/jmir.5585
Klembczyk JJ, et al. Google Flu Trends Spatial Variability Validated Against Emergency Department Influenza-Related Visits. J Med Internet Res. 2016 06 28;18(6):e175. PubMed PMID: 27354313.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Google Flu Trends Spatial Variability Validated Against Emergency Department Influenza-Related Visits. AU - Klembczyk,Joseph Jeffrey, AU - Jalalpour,Mehdi, AU - Levin,Scott, AU - Washington,Raynard E, AU - Pines,Jesse M, AU - Rothman,Richard E, AU - Dugas,Andrea Freyer, Y1 - 2016/06/28/ PY - 2016/01/30/received PY - 2016/05/10/accepted PY - 2016/05/05/revised PY - 2016/6/30/entrez PY - 2016/6/30/pubmed PY - 2017/9/14/medline KW - emergency department KW - google flu trends KW - influenza KW - infoveillance KW - surveillance SP - e175 EP - e175 JF - Journal of medical Internet research JO - J. Med. Internet Res. VL - 18 IS - 6 N2 - BACKGROUND: Influenza is a deadly and costly public health problem. Variations in its seasonal patterns cause dangerous surges in emergency department (ED) patient volume. Google Flu Trends (GFT) can provide faster influenza surveillance information than traditional CDC methods, potentially leading to improved public health preparedness. GFT has been found to correlate well with reported influenza and to improve influenza prediction models. However, previous validation studies have focused on isolated clinical locations. OBJECTIVE: The purpose of the study was to measure GFT surveillance effectiveness by correlating GFT with influenza-related ED visits in 19 US cities across seven influenza seasons, and to explore which city characteristics lead to better or worse GFT effectiveness. METHODS: Using Healthcare Cost and Utilization Project data, we collected weekly counts of ED visits for all patients with diagnosis (International Statistical Classification of Diseases 9) codes for influenza-related visits from 2005-2011 in 19 different US cities. We measured the correlation between weekly volume of GFT searches and influenza-related ED visits (ie, GFT ED surveillance effectiveness) per city. We evaluated the relationship between 15 publically available city indicators (11 sociodemographic, two health care utilization, and two climate) and GFT surveillance effectiveness using univariate linear regression. RESULTS: Correlation between city-level GFT and influenza-related ED visits had a median of .84, ranging from .67 to .93 across 19 cities. Temporal variability was observed, with median correlation ranging from .78 in 2009 to .94 in 2005. City indicators significantly associated (P<.10) with improved GFT surveillance include higher proportion of female population, higher proportion with Medicare coverage, higher ED visits per capita, and lower socioeconomic status. CONCLUSIONS: GFT is strongly correlated with ED influenza-related visits at the city level, but unexplained variation over geographic location and time limits its utility as standalone surveillance. GFT is likely most useful as an early signal used in conjunction with other more comprehensive surveillance techniques. City indicators associated with improved GFT surveillance provide some insight into the variability of GFT effectiveness. For example, populations with lower socioeconomic status may have a greater tendency to initially turn to the Internet for health questions, thus leading to increased GFT effectiveness. GFT has the potential to provide valuable information to ED providers for patient care and to administrators for ED surge preparedness. SN - 1438-8871 UR - https://www.unboundmedicine.com/medline/citation/27354313/Google_Flu_Trends_Spatial_Variability_Validated_Against_Emergency_Department_Influenza_Related_Visits_ L2 - https://www.jmir.org/2016/6/e175/ DB - PRIME DP - Unbound Medicine ER -