Forum for Nordic Dermato-Venereology Nr 4, 2019 | Page 26

Letter to the Editor
Nicolas Kluger – Hidradenitis suppurativa: analysis of Google Trends searches in Europe between 2009 and 2019
Hidradenitis Suppurativa: Analysis of Google Trends Searches in Europe
Between 2009 and 2019
N icolas K luger
Department of Dermatology, Allergology and Venereology, Helsinki University Hospital, Meilahdentie 2, PO Box 160, FIN-
00029, Helsinki, Finland. E-mail: [e-mail].
Dear Editor,
100
a
World wide
90
We analysed the data generated through GT for the RSVs on
the topic “hidradenitis suppurativa, disease”, worldwide and
for 10 European countries from 1 January 2009 to 11 August
2019. The results are displayed as a set of time series. The values
are not actual search counts, but are percentages relative to
the total searches across the specified geographical area and
time period. The resulting numbers are then scaled from 0 to
100, based on the proportion of all searches on all topics. All
data used in this study are publicly available, anonymous,
and cannot be traced back to identifiable individuals. For this
study, we calculated the mean value of RSVs/year/country.
Between 2009 and 2015, worldwide interest in HS remained
stable, but increased progressively after 2015/16 (Fig. 1). Almost
all countries have experienced a slow increase since 2009. We
observed similar trends within neighbouring countries, or those
with similar latitudes (e.g. UK and France, Spain and Italy,
Sweden and Finland). Countries such as Germany and Russia
display a “flatter” trend compared with other countries. Almost
all countries showed an increased after 2015/16. We found no
seasonality in search trends by country (e.g. summer/winter).
Notable isolated peaks were observed; for example, in Germany
in April 2012, France in September 2016 and April 2018, and
Finland in January 2016. Repetitive peaks were observed in
Spain during the weeks 3–9 June 2017, 2018 and 2019.
Overall, interest in HS on the Internet has increased very
progressively, as observed previously by Hessam et al. (5).
However, in contrast to some other conditions, such as mel-
anoma (2, 3) or vitiligo (4), there does not seem to be any
notable seasonality guiding the search trend. Peaks were noted
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Finland
Sweden
50
Norway
40
30
20
Denmark
Conflicts of interest: Dr Nicolas Kluger has served as a consultant
to AbbVie, and has received research funding from AbbVie and
speaker fees from AbbVie (2015–2016).
R eferences
1. Zouboulis CC, Bechara FG, Dickinson-Blok JL, Gulliver W, Horváth
B, Hughes R, et al. Hidradenitis suppurativa/acne inversa: a practi-
cal framework for treatment optimization – systematic review and
recommendations from the HS ALLIANCE working group. J Eur
Acad Dermatol Venereol 2019; 33: 19–31.
2. Bloom R, Amber KT, Hu S, Kirsner R. Google search trends and skin
cancer: evaluating the US population’s interest in skin cancer and
its association with melanoma outcomes. JAMA Dermatol 2015;
151: 903–905.
3. Kluger N, Bouchard LJ. A comparative study of Google search
trends for melanoma, breast cancer and prostate cancer in Finland.
Dermatology 2019; 235: 346–347.
4. Kluger N. The Michael Jackson and the Winnie Harlow effect: im-
pact on vitiligo awareness on the Internet. J Clin Aesth Dermatol
2019; 12: 12–13 .
5. Hessam S, Salem J, Bechara FG, Haferkamp A, Heidenreich A,
Paffenholz P, et al. Hidradenitis suppurativa gains increasing in-
terest on World Wide Web: a source for patient information? Int
J Dermatol 2017; 56: 726–732.
10
0
2009
2010
2011
Denmark
2012
2013
2014
2015
Norway
Sweden
Finland
2016
2017
World wide
2018
2019
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b
World wide
90
Hidradenitis suppurativa (HS) is a chronic inflammatory
disease of the apocrine glands that affects approximately 1%
of the general population (1). Google Trends (GT) is a useful
website (https://www.google.com/trends/) that provides data
on the relative search volume of queries (RSVs) and topics
over time and across geographical areas (worldwide, country).
It allows the seasonal and long-term assessment of trends in
public interest. GT is currently used in healthcare research,
including dermatology (2–4) and HS (5).
increase in number of search queries, underlining the impor-
tance of public events and media focus for increasing disease
awareness (5). In addition, health-related reality shows, such
as Dr Pimple Popper in the USA, or Embarrassing Bodies in the
UK, which show patients with HS in a more dramatic way, may
also have an impact. Lastly, the notable increase since 2016
may be related to the approval of adalimumab by the Euro-
pean Medicines Agency (EMA) to treat HS. There is a notable
parallel trend between searches for adalimumab and HS (data
not shown). This increase may be related to advertisement
campaigns by pharmaceutical companies for adalimumab or
by patients looking for information regarding this treatment.
Limitations of the current study include that GT is not an
epidemiological tool; the results include only individuals
with access to the internet; and direct comparisons of RSVs
between countries is not possible.
80 France
70 United
Kingdom
60 Italy
Spain
50
Poland
40
Russia
30
Germany
20
10
0
2009
2010
2011
2012
United Kingdom
France
2013
2014
2015
Spain
Italy
Germany
2016
Poland
2017
Russia
2018
2019
World wide
Fig. 1. Interest in hidradenitis suppurativa (HS), reflected by the Google
search topic “hidradenitis suppurativa” between 2009 and 2019, adjusted
for (a) worldwide and Northern Europe and (b) the rest of Europe. The
red arrow indicates the year 2016 after approval of adalimumab by the
European Medicines Agency (EMA). Note: Data for Northern Europe
and the rest of Europe are on separate figures so as not to overload one
figure. In addition, RSV values cannot be compared between countries;
only the trends can be compared.
at various periods of time in some countries. Such peaks are
usually related to increased media coverage, either because
of an information campaign by a patients’ association (e.g.
in France in September 2016), national media coverage (e.g.
in Finland in January 2019) or health shows on TV reporting
on the disease (e.g. in France in April 2018 or Germany in
2012 (5)). HS “world day” or “awareness week” has now been
scheduled for the beginning of June. Awareness campaigns
explain peaks during the beginning of June; for example,
as observed strikingly in Spain. Media reports influence the
Forum for Nord Derm Ven 2019, Vol. 24, No. 4
Forum for Nord Derm Ven 2019, Vol. 24, No. 4
L etter to the E ditor
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