Comment
surgery to prevent SSI.11,12 The retraction of several trials
has raised further concerns regarding the evidence
base.13 The COVID-19 pandemic has highlighted the
importance of oxygen as a scarce health-care resource,
emphasising the need to establish the evidence for
the recommendation for liberal inspired oxygen to
prevent SSI. This issue is being addressed in another
large pragmatic trial (PErioperative respiratory care and
outcomes for patieNts Undergoing hIgh risk abdomiNal
surgery [PENGUIN], NCT04256798) also led by the NIHR
Global Health Research Unit on Global Surgery.
The work by the NIHR Global Health Research Unit on
Global Surgery has answered (through the FALCON trial)
and is answering (through the PENGUIN trial) important
questions relating to appropriate and cost-effective
interventions for SSI in low-resource environments. These
data will improve care and allow appropriate allocation of
scarce resources.
1
2
3
4
5
6
7
8
9
10
BMB is a co-principal investigator of the NIHR Global Health Research Unit on
Global Surgery PENGUIN trial. BMB received financial support to attend the NIHR
Global Health Research Unit on Global Surgery meetings in Ghana in 2019,
Rwanda in 2018, and South Africa in 2017. VM and ALS declare no competing
interests.
11
*Bruce M Biccard, Vanessa Msosa, Ahmadou L Samateh
12
bruce.biccard@uct.ac.za
Department of Anaesthesia and Perioperative Medicine, Groote Schuur Hospital,
Faculty of Health Sciences, University of Cape Town, Cape Town 7935, South Africa
(BMB); Kamuzu Central Hospital, Lilongwe, Malawi (VM); School of Medicine and
Allied Health Sciences, University of The Gambia, Banjul, The Gambia (ALS)
13
WHO. Universal Health Coverage. 2021. https://www.who.int/
healthsystems/universal_health_coverage/en/ (accessed May 4, 2021).
Schäferhoff M, Martinez S, Ogbuoji O, Sabin ML, Yamey G. Trends in global
health financing. BMJ 2019; 365: l2185.
WHO. Global spending on health: weathering the storm. Geneva:
WHO, 2020.
Meara JG, Leather AJ, Hagander L, et al. Global surgery 2030: evidence and
solutions for achieving health, welfare, and economic development. Lancet
2015; 386: 569–624.
GlobalSurg Collaborative. Mortality of emergency abdominal surgery
in high-, middle- and low-income countries. Br J Surg 2016;
103: 971–88.
Biccard BM, Madiba TE, Kluyts HL, et al. Perioperative patient outcomes in
the African Surgical Outcomes Study: a 7-day prospective observational
cohort study. Lancet 2018; 391: 1589–98.
Platt E, Doe M, Kim NE, et al. Economic impact of surgery on households
and individuals in low income countries: a systematic review. Int J Surg
2021; 90: 105956.
NIHR Global Research Health Unit on Global Surgery. Reducing surgical site
infections in low-income and middle-income countries (FALCON):
a pragmatic, multicentre, stratified, randomised controlled trial. Lancet
2021; published online Oct 25. https://doi.org/10.1016/
S0140-6736(21)01548-8.
GlobalSurg Collaborative. Surgical site infection after gastrointestinal
surgery in high-income, middle-income, and low-income countries:
a prospective, international, multicentre cohort study. Lancet Infect Dis
2018; 18: 516–25.
World Health Organization. Global guidelines for the prevention of surgical
site infection, 2016. http://apps.who.int/iris/bitstream/hand
le/10665/250680/9789241549882-eng.pdf (accessed July 8, 2021).
Allegranzi B, Bischoff P, de Jonge S, et al. New WHO recommendations
on preoperative measures for surgical site infection prevention:
an evidence-based global perspective. Lancet Infect Dis 2016;
16: e276–87.
Allegranzi B, Zayed B, Bischoff P, et al. New WHO recommendations on
intraoperative and postoperative measures for surgical site infection
prevention: an evidence-based global perspective. Lancet Infect Dis 2016;
16: e288–303.
Myles PS, Carlisle JB, Scarr B. Evidence for compromised data integrity in
studies of liberal peri-operative inspired oxygen. Anaesthesia 2019;
74: 573–84.
The COVID-19 pandemic has taken a toll on people’s
mental health. Yet, the global extent of this impact
remains largely unknown. By leveraging the best
available data from surveys around the world with
measurements of anxiety and depression both before
and during the pandemic, and analysing these data
using the Global Burden of Disease Study (GBD) model,
the COVID-19 Mental Disorders Collaborators1 provide
global insight into the burden of depression and anxiety
disorders during the pandemic to date. The authors
estimated a significant increase in the prevalence of both
major depressive disorder (with an estimated additional
53·2 million [95% uncertainty interval 44·8–62·9]
cases worldwide—ie, a 27·6% [25·1–30·3] increase) and
www.thelancet.com Vol 398 November 6, 2021
anxiety disorders (76·2 million [64·3–90·6] additional
cases—ie, a 25·6% [23·2–28·0] increase) since before
the pandemic. Increased prevalence was seen for both
males and females across the lifespan. These findings are
all the more concerning because depressive and anxiety
disorders were already leading causes of disability
worldwide.2
The study has unique strengths. First, by using
the GBD model, it translates crude estimates from
heterogeneous surveys into numbers of additional
cases and disability-adjusted life-years. This makes the
findings more tangible for policy makers, academics,
charities, and the general public. Second, the study
leverages data on COVID-19 impact indicators (ie,
Tom Merton/Caia Image/Science Photo Library
Depression and anxiety disorders during the COVID-19
pandemic: knowns and unknowns
Published Online
October 8, 2021
https://doi.org/10.1016/
S0140-6736(21)02221-2
See Articles page 1700
1665
Comment
human mobility, SARS-CoV-2 infection rates, and
excess mortality). The COVID-19 Mental Disorders
Collaborators estimated these indicators for all
countries and territories and used them to inform the
extrapolation of changes in prevalence to countries
with no available survey data. Furthermore, the
authors assessed the generalisability of their estimates
for countries with no available surveys using a leaveone-country-out cross-validation approach, in which
changes in prevalence were estimated using the GBD
model as if survey data for one country were not
available and the prediction was then compared with
the actual survey data.
The study also has a few key limitations, largely
resulting from the available data rather than
the approach used to analyse them. First, direct
measurements on changes in prevalence of depressive
and anxiety disorders are not available in large regions
of the world (eg, within South America and Africa).
For these regions, the GBD model has to extrapolate
estimates from other regions (eg, the USA or Europe),
which are very different on many levels (economically,
demographically, politically, and culturally). This
extrapolation might be unreliable, as shown in the
cross-validation results. For instance, the GBD model
predicts a substantial increase in the prevalence of
major depressive disorder in Denmark and almost no
change in China whereas the opposite is observed in
surveys (appendix of Article [p 24]). Second, most of
the available data are based on self-report scales (eg,
Patient Health Questionnaire-9 or General Anxiety
Disorder-7 [GAD-7]), which measure symptoms rather
than actual diagnoses. Although both symptoms and
diagnoses are important, the difference between them
is relevant in the pandemic context. A diagnosis of
anxiety disorder according to the tenth International
Classification of Diseases and Related Health Problems
requires that individuals recognise their emotional
distress as excessive or unreasonable. GAD-7 does not
capture this aspect. For an individual at high risk of
COVID-19 complications to constantly feel nervous and
afraid would not be unreasonable (hence, not meeting
requirements for an anxiety disorder), yet it would
yield a high GAD-7 score. Finally, the study is unable
to identify what is causing the increased burden of
major depressive disorder and anxiety. In particular, the
relative contributions to the prevalence of depression
1666
and anxiety disorders of direct consequences of
COVID-19 illness,3 some measures used to curb the
propagation of the virus (eg, lockdowns),4 and other
correlates of the pandemic (eg, economic austerity)
remain elusive.
By synthesising the best available data, this study
not only reveals what we do know, but also—crucially—
exposes what we still do not know. These known
unknowns have implications for interpretation of the
findings. The paucity of direct measurements in most
countries implies that the findings are unable to inform
on specific countries that have been more affected
than others. Aid programmes aimed at improving
population mental health are clearly needed widely,
and this study is unable to suggest specific countries
to be targeted first. Measurement of clinical diagnoses
will be needed to plan service provision, ascertain the
burden of the pandemic in terms of mental disorders,
and forecast social and economic consequences.
Crucially, identifying causal mechanisms, and
modifiable mechanisms in particular, will be important
to design and deliver the right interventions to the
right people.5
The findings of this study should urgently incentivise
more research to determine the fuller geographical
distribution of depression and anxiety disorders, the
prevalence of depressive and anxiety disorders, and the
underpinning mechanisms to improve mental health in
the context of the COVID-19 pandemic globally.
We declare no competing interests.
*Maxime Taquet, Emily A Holmes, Paul J Harrison
maxime.taquet@psych.ox.ac.uk
Department of Psychiatry, University of Oxford, Oxford, OX3 7JX, UK (MT, PJH);
Oxford Health NHS Foundation Trust, Oxford, UK (MT, PJH); Department of
Psychology, Uppsala University, Uppsala, Sweden (EAH); Department of Clinical
Neuroscience, Karolinska Institutet, Stockholm, Sweden (EAH)
1
2
3
4
5
COVID-19 Mental Disorders Collaborators. Global prevalence and burden of
depressive and anxiety disorders in 204 countries and territories in 2020
due to the COVID-19 pandemic. Lancet 2021; published online Oct 8.
https://doi.org/10.1016/S0140-6736(21)02143-7.
Murray CJL, Vos T, Lozano R, et al. Disability-adjusted life years (DALYs)
for 291 diseases and injuries in 21 regions, 1990–2010: a systematic
analysis for the Global Burden of Disease Study 2010. Lancet 2012;
380: 2197–223.
Taquet M, Geddes JR, Husain M, Luciano S, Harrison PJ. 6-month
neurological and psychiatric outcomes in 236 379 survivors of COVID-19:
a retrospective cohort study using electronic health records.
Lancet Psychiatry 2021; 8: 416–27.
Marroquín B, Vine V, Morgan R. Mental health during the COVID-19
pandemic: effects of stay-at-home policies, social distancing behavior,
and social resources. Psychiatry Res 2020; 293: 113419.
Holmes EA, O’Connor RC, Perry VH, et al. Multidisciplinary research
priorities for the COVID-19 pandemic: a call for action for mental health
science. Lancet Psychiatry 2020; 7: 547–60.
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