Is Google Trends a reliable tool for digital epidemiology? Insights from different clinical settings

Abstract

Internet-derived information has been recently recognized as a valuable tool for epidemiological investigation. Google Trends, a Google Inc. portal, generates data on geographical and temporal patterns according to specified keywords. The aim of this study was to compare the reliability of Google Trends in different clinical settings, for both common diseases with lower media coverage, and for less common diseases attracting major media coverage. We carried out a search in Google Trends using the keywords "renal colic", "epistaxis", and "mushroom poisoning", selected on the basis of available and reliable epidemiological data. Besides this search, we carried out a second search for three clinical conditions (i.e., "meningitis", "Legionella Pneumophila pneumonia", and "Ebola fever"), which recently received major focus by the Italian media. In our analysis, no correlation was found between data captured from Google Trends and epidemiology of renal colics, epistaxis and mushroom poisoning. Only when searching for the term "mushroom" alone the Google Trends search generated a seasonal pattern which almost overlaps with the epidemiological profile, but this was probably mostly due to searches for harvesting and cooking rather than to for poisoning. The Google Trends data also failed to reflect the geographical and temporary patterns of disease for meningitis, Legionella Pneumophila pneumonia and Ebola fever. The results of our study confirm that Google Trends has modest reliability for defining the epidemiology of relatively common diseases with minor media coverage, or relatively rare diseases with higher audience. Overall, Google Trends seems to be more influenced by the media clamor than by true epidemiological burden.

Keywords: Digital epidemiology; Epistaxis; Google Trends; Mushroom poisoning; Renal colic.

Fig. 1.

Number of renal colics seen in the ED, and average of Google Trends Index (referred to the Parma Province), calculated monthly, years 2007–2016.

Fig. 2.

Number of epistaxis episodes seen in the ED, and average of Google Trends Index (referred to the Parma Province) (double search, i.e., “epistaxis” and “nose bleeding”), calculated monthly, years 2007–2016.

Fig. 3.

Number of mushroom poisonings seen in the ED, and average of Google Trends Index (referred to the Parma Province) (double search, i.e., “mushrooms” and “mushroom poisoning”), calculated monthly, years 2007–2016.

Fig. 4.

Number of meningococcal meningitis in the Emilia Romagna Region, and average of Google Trends Index (referred to the Parma Province) (term “meningitis”), calculated monthly, year 2016.

Fig. 5.

Number of Legionella Pneumophila pneumonia in the Province of Parma, and average of Google Trends Index (referred to the Parma Province) (term “legionella”), calculated monthly, year 2016.

Fig. 6.

Number of Ebola virus fever in the Emilia Romagna region, and average of Google Trends Index (referred to the Parma Province) (term “Ebola”), calculated monthly, year 2014.

Fig. 7.

Comparison of the average Google Trends Indexes for five different medical terms (i.e., renal colic, myocardial infarction, influenza, vaccines, and autism), Emilia Romagna Region, year 2016.