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American Journal of  Medical 
Science and Innovation (AJMSI) 

Rapid Sequence Intubation in the ER Using Video Laryngoscopy and Direct Laryngoscopy
Marina Botras1*, Islam Elsaka1, Mohammad Zalzalah1, Mariam Ayed2, Fatemah Qasem3

Volume 4 Issue 1, Year 2025
ISSN: 2836-8509 (Online)

DOI: https://doi.org/10.54536/ajmsi.v4i1.3182
https://journals.e-palli.com/home/index.php/ajmsi

Article Information ABSTRACT

Received: August 02, 2024
Accepted: September 04, 2024
Published: February 08, 2025

Endotracheal intubation, or EI, is a common procedure in the ICU, particularly for critically 
ill patients who require mechanical ventilation or airway compromise. This patient population 
presents unique challenges, including anatomic conditions, physiologic factors, logistics, and 
operator experience. The objective of  the systematic was to assess the efficacy of  video 
laryngoscopy compared to direct laryngoscopy in rapid sequence intubation procedures, 
particularly in intensive care units, intending to evaluate various outcomes such as laryngeal 
visualization, intubation success rates, time to intubation, and other complications. Systematic 
review and meta-analysis of  nineteen have been conducted according to PRISMA guidelines, 
sourcing articles from January 2005 to February 2023 across databases like PubMed and 
Google Scholar. Studies in English comparing video laryngoscopy and direct laryngoscopy 
for rapid sequence intubation were included. Quality assessment adhered to Cochrane risk 
of  bias guidelines, and the meta-analysis utilized a Mantel-Haenszel random-effect model 
with a 95% confidence interval for precision. The results concluded that VL exhibited higher 
first-attempt intubation success rates than DL, but no significant differences were observed 
in overall success rates. Time to intubation showed a slight reduction with VL compared to 
DL, while complications such as hypotension and dental trauma were moderately higher 
with VL. In summary, the utilization of  VL in rapid sequencing intubation has been linked 
to a reduced time to achieve successful intubation compared to DL. However, additional 
analysis, such as hospital duration of  stays, follow-up time, and monitoring of  adverse 
events, has been necessary for a thorough meta-analysis.

Keywords
Direct Laryngoscopy, Video 
Laryngoscopy, Meta-Analysis, 
Rapid Sequencing, Intubations, 
Emergency

1 Kuwait Board of  Anesthesia, Kuwait institute of  medical specialization, Kuwait
2 Department Neonatal Intensive Care, Maternity hospital, Ministry of  Health, Kuwait
3 Department of  Anesthesia and Intensive Care, Maternity Hospital, Ministry of  Health, Kuwait
* Corresponding author’s e-mail: Ashraf_SobhI12@outlook.com

INTRODUCTION
Endotracheal intubation, or EI, is a common procedure in 
the ICU, particularly for critically ill patients who require 
mechanical ventilation or airway compromise (Hypes 
et al., 2016). This patient population presents unique 
challenges, including anatomic conditions, physiologic 
factors, logistics, and operator experience. The Risk of  
complications increases with repeated attempts and the 
inability to abandon intubation attempts. It has become 
crucial to develop methods to optimize chances for first-
attempt success (Baek et al., 2018). EI is associated with 
a higher rate of  complications outside the emergency 
room than inside. Successful intubation at first attempt 
is important in emergency settings, as multiple intubation 
attempts have been associated with several complications 
(Baek et al., 2018).
Prehospital intubations (PI) may differ from clinical 
intubations due to impaired patient access and airway 
access, neck and face Trauma, an oral intake history, or 
the potential for body fluids in the airway. Monitoring, 
equipment, limited care providers, and environmental 
issues can impede EI (Cavus et al., 2018). PI relies on 
airway devices that are easy to use, quick, and reliable. 
Over the past few years, Macintosh Laryngoscopy (ML) 
has performed Direct Laryngoscopy (DL). Due to several 
drawbacks, recently, Video Laryngoscopy (VL), a device 
that has been developed, comprises a miniaturized camera 
at the tip of  the blade for an indirect visualization of  the 
glottis.  

Direct Laryngoscopy 
Direct laryngoscopy (DL) is the most common 
emergency EI  method, introduced over 50 years ago 
(Goksu et al., 2016). The Macintosh laryngoscope (MCL) 
was the ‘gold standard’ device for DL and EI, invented 
by Foregger in the 1940s (Pournajafian et al., 2014). The 
technique involves high forward and upward force on the 
handle to visualize the glottis by aligning oral, pharyngeal, 
and laryngeal axes (Panwar et al., 2020). DL has been the 
primary technique for or Tracheal Intubation (TI) in the 
ICU, but it has been associated with a concerning the rate 
of  challenging intubations and other complications in 
ICU (Panwar et al., 2020).

Video Laryngoscopy
Over the past decade, various airway equipment, 
including a VL, has been developed and compared to 
conventional ML (Dey et al., 2020). VL, a device with 
a camera attached to the blade tip, might increase the 
first-attempt intubation success rate (Baek et al., 2018; 
Hypes et al., 2016). It allows operators to direct the tube 
without visualization, potentially improving performance. 
VL requires less airway manipulation, resulting in less 
hemodynamic stress responses. Studies suggest that, as 
compared to DL, VL yields a higher success rate for first-
attempt intubation (Gao et al., 2018; Goksu et al., 2016)

METHODOLOGY
The present research performed a systematic review and 



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meta-analysis following the “Preferred Reporting Items 
for Systematic Reviews and Meta-analysis” (PRISMA) 
guidelines. 

Data Source and Search Strategy 
Articles were retrieved for publication from January 2005 
to February 2023 from three databases: “PubMed, Google 
Scholar, and Cochrane Library”. The strategy was based 
on the population, intervention, control and outcome 
(PICO) format. The population of  interest was critically 
ill adults admitted for rapid sequence intubations; the 
intervention was video laryngoscopy; the comparison 
was direct laryngoscopy, and the outcomes of  interest are 
first attempt intubation success rate, time of  intubations, 
and complication arising from intubation. 
The search was performed using the following keywords; 
“Fiberoptic intubation” OR “C-MAC rapid sequence 
intubation” “Rapid sequence induction” AND “C-MAC” 
OR “Direct laryngoscopy” OR “Video-assisted devices” 
OR “Video laryngoscopy “OR “Crush induction.” To 
retrieve more articles, reference lists were used.

Mesh Terms
“(“video’s”[All Fields] OR “videoed”[All Fields] 
OR “videotape recording”[MeSH Terms] OR 
(“videotape”[All Fields] AND “recording”[All Fields]) 
OR “videotape recording”[All Fields] OR “video”[All 
Fields] OR “videos”[All Fields] OR “VL”[All Fields] 
OR ((“direct”[All Fields] OR “directed”[All Fields] OR 
“directing”[All Fields] OR “direction”[All Fields] OR 
“directional”[All Fields] OR “directions”[All Fields] OR 
“directivities”[All Fields] OR “directivity”[All Fields] 
OR “directs”[All Fields]) AND (“laryngoscopy”[MeSH 
Terms] OR “laryngoscopy”[All Fields] OR 
“laryngoscopies”[All Fields])) OR “DL”[All Fields]) 
AND ((“rapid”[All Fields] OR “rapidities”[All Fields] 
OR “rapidity”[All Fields] OR “rapidness”[All Fields]) 
AND (“base sequence”[MeSH Terms] OR (“base”[All 
Fields] AND “sequence”[All Fields]) OR “base 
sequence”[All Fields] OR “sequence”[All Fields] OR 
“sequences”[All Fields] OR “sequence analysis”[MeSH 
Terms] OR (“sequence”[All Fields] AND “analysis”[All 
Fields]) OR “sequence analysis”[All Fields] OR 
“sequencing”[All Fields] OR “sequence s”[All Fields] OR 
“sequenceable”[All Fields] OR “sequenced”[All Fields] 
OR “sequenceing”[All Fields] OR “sequencer”[All Fields] 
OR “sequencers”[All Fields] OR “sequencies”[All Fields] 
OR “sequencings”[All Fields]))) OR “RSI”[All Fields] 
OR (“rapid sequence induction and intubation”[MeSH 
Terms] OR (“rapid”[All Fields] AND “sequence”[All 
Fields] AND “induction”[All Fields] AND 
“intubation”[All Fields]) OR “rapid sequence induction 
and intubation”[All Fields] OR (“rapid”[All Fields] 
AND “sequence”[All Fields] AND “intubation”[All 
Fields]) OR “rapid sequence intubation”[All Fields]) 
OR (“intubate”[All Fields] OR “intubated”[All Fields] 
OR “intubates”[All Fields] OR “intubating”[All Fields] 
OR “intubation”[MeSH Terms] OR “intubation”[All 

Fields] OR “intubations”[All Fields] OR “intubator”[All 
Fields] OR “intubator s”[All Fields] OR “intubators”[All 
Fields])) AND (“clinical trial”[Publication Type] OR 
“clinical trials as topic”[MeSH Terms] OR “clinical 
trial”[All Fields])) OR “RCT”[All Fields]) AND 
(randomizedcontrolledtrial[Filter]).”

Eligibility Criteria 
The selected studies had to be clinical trials conducted in 
a medical setting to establish the significance of  VL and 
DL, used for rapid sequence intubations. The eligibility 
criteria were grouped into inclusion and exclusion criteria.

Inclusion Criteria 
The inclusion criteria were applied during the search 
process and study selection. Articles published in English 
between 2005 and 2023, as well as clinical studies and 
randomized trials (control), comparing the efficacy of  VL 
and DL, have been included. The population of  interest is 
Adults admitted for rapid sequence intubation. We include 
studies that reported the incubation time, first and second 
attempt intubation, and complications after intubation. 

Exclusion Criteria 
The articles published before 2005, articles without 
an abstract or control group, and articles published in 
another language rather than English have been excluded. 
Study designs such as case studies, retrospectives, journals, 
magazines, and meta-analyses were excluded.

Study Selection 
The inclusion and exclusion criteria were used in the 
selection process. After conducting a comprehensive 
database search, the articles that were obtained underwent 
filtering and screening by two independent authors to 
validate and ensure adherence to both the inclusion and 
exclusion criteria.  For the removal of  duplicates, all 
articles were collected in the Endnote library and then 
exported into an Excel sheet. For screening of  essential 
information, remaining references were also exported 
to an Excel file. The screening was done in phases: the 
first was through the title and abstracts, and the second 
was full-text screening. The quality assessment of  the 
remaining studies was the last phase of  screening.

Quality Assessment 
Cochrane risk of  bias guidelines has been utilized to 
assess the quality of  the remaining articles. To avoid 
any risk of  bias at different time frames, the data was 
extracted twice by utilizing the similar search words. Low, 
high, and unclear were utilized as the defined range of  
Risk of  bias. For Systematic Reviews of  Interventions, 
the Cochrane Handbook was followed and focused 
particularly on the following factors: “random-sequence 
generation, allocation concealment, blinding, outcome 
assessment, selective reporting of  selected studies, and 
the percentage of  each measure will be accessed through 
a visualization graph”.



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Risk of  Bias Assessment
Using the Cochrane risk of  bias guidelines, The Risk 
of  bias in the included studies was evaluated by two 
independent reviewers. Each study was assessed for the 
following domains:

Random Sequence Generation
This domain assessed whether the randomization process 
was adequately described and conducted to minimize 
selection bias. Studies were categorized as having low 
Risk if  they described a random sequence generation 
method such as computer-generated randomization or 
random number tables.

Allocation Concealment
Allocation concealment evaluates whether the method 
used to conceal the allocation sequence was adequate to 
prevent selection bias. Studies were categorized as having 
low Risk if  they described methods such as centralized 
randomization or sealed opaque envelopes.

Blinding of  Participants and Personnel
Blinding assesses whether participants, personnel, and 
outcome assessors were blinded to the intervention to 
minimize performance and detection bias. Studies were 
categorized as having low Risk if  they reported blinding 
of  participants and personnel, blinding of  outcome 
assessors, or if  blinding was not applicable.

Blinding of  Outcome Assessment
This domain assesses whether outcome assessors were 
blinded to the intervention allocation when measuring 
outcomes to minimize bias in outcome assessment. For 
the blinded outcome assessors, studies were categorized 
as having low Risk, high Risk if  outcome assessors were 
not blinded, and unclear if  the blinding status was not 
reported.

Incomplete Outcome Data
This domain evaluates whether there were missing outcome 
data and whether handling missing data was appropriate to 
minimize attrition bias. Studies were categorized as having 
low Risk if  they reported low rates of  missing data or if  
appropriate methods, such as intention-to-treat analysis, 
were used to handle missing data.

Selective Reporting
Selective reporting assesses whether all predefined 
outcomes were reported to minimize reporting bias. 
Studies were categorized as having low Risk if  they 
reported all prespecified outcomes or if  the study 
protocol was available and followed.

Other Biases
This domain assesses other sources of  bias that could 
affect the study’s results, such as conflicts of  interest or 
funding sources. Studies were categorized based on the 
presence or absence of  potential sources of  bias.

Data Extraction and Synthesis 
In a predefined Excel sheet, the following variables were 
extracted: Author’s first name, study design, country of  
publication, number of  participants, reason for intubation, 
medical setting (Emergency or ICU), techniques used 
(VL, DL), age of  patients in the intervention group 
(mean, SD), gender (Number and percentage of  Male 
only), number and percentage of  patients underwent 
Rapid sequence intubation, age and gender of  patients 
in the control group. For the meta-analysis, the number 
of  patients randomized into intervention and control 
groups, the time of  intubation, and the number of  first 
attempt intubation success rates were extracted.
The meta-analysis was performed using RevMan Version 
5.4 Cochrane review software. An effect model called 
Mantel-Haenszel random, was chosen due to patient 
allocation techniques across all trials. The heterogeneity 
was measured using (I2). The authors opted to estimate 
the analysis results within the confidence interval of  95%, 
which indicated that, on either side of  the distribution, 
only a 2.5% error was allowed. The level of  precision also 
indicated that the p-value of  less than 0.05 indicates the 
significance of  the results. Additionally, the index of  the 
effect size and the homogeneity in each sample, has been 
chosen by a unique precision of  each study.

RESULTS 
Study Selection 
Two thousand eight hundred articles were retrieved 
from all databases and 13 through manual search. After 
removing 601 duplicates, the remaining articles were 
screened by two independent authors. The first phase of  
screening was going through the title and abstracts. After 
the first phase, 113 articles were remained for screening. 
The authors screened the full text of  the articles, and 
94 articles were excluded due to different scopes of  the 
studies, poor methodology, lack of  control groups, and 
absence of  data analysis in a few articles. The remaining 19 
articles were included in the meta-analysis and synthesis 
of  results. The PRISMA flowchart shows the process of  
study selection (Figure 1).

Characteristics of  Included Studies 
From nineteen randomized control trials, 14 studies 
reported Rapid Sequence Intubation (RSI) in the 
Emergency medical service (EMS) setting, while 5 
studies performed RSI at the intensive care unit (ICU). 
The participants comprise adults with average ages 
ranging from 37 years to 73 years (Ducharme et al., 2017; 
Sanguanwit et al., 2021). The average and total number 
of  patients across all 19 studies were 267.85 and 5357, 
respectively. The reasons for intubation reported by the 
patients are Respiratory Failure (RF), Airway Protection, 
EI, multiple Trauma, Congestive Heart Failure, and 
Emergency Intubation. The experiments were conducted 
in 12 countries (USA, Canada, Switzerland, Korea, UK, 
India, Poland, China, France, Thailand, Palatine and 
Australia).



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Quality Assessment of  the Included Studies 
The Risk of  bias tools for randomized control trials were 
used to assess the quality of  the included studies. Under 
the domain of  Random Sequence Generation, Allocation 
Concealment, Blinding of  Participants and Personnel, 
Blinding of  Outcome Assessment, and other biases, 96% 
of  all studies reported a low Risk of  bias and 4% high risk 
of  bias. Under the incomplete outcome data and selective 
reporting, all the included studies reported a 100% low 
risk of  bias, as shown in Figure 2. The summary of  the 
quality assessment graph is presented in (Figure 2).

Outcome Measures in the Included Studies 
The first outcome measures were the success rate of  
the first and second TI attempts. The patients were 
randomized to VL and DL groups in 19 trials. The 
number of  participants randomized to receive VL and 
DL were recorded and analyzed. The complications from 
TI bastion and time of  intubation in both groups were 
also recorded and analyzed.
 
Prisma Flow Chart

Figure 1: The PRISMA diagram of  the study selection process

Table 1: 
Author Information Participants Intervention Control Group

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Outcome Measures of  Risk of  Bias Assessment

Figure 2: Results of  the quality assessment using the Risk of  bias tool



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Results of  Meta-Analysis
Comparison of  the Efficacy of  Rapid Sequence 
Intubation by DL and VL
To investigate if  VL or DL for EI provides better 
laryngeal visualization, nineteen trials were included in the 
meta-analysis. The Mantel-Haenszel random effect meta-
analysis showed no significant differences between VL 

and DL “(OR = 1.38, 95% Confidence interval 0.81 to 
2.35, p = 0.23)”. The studies had significant heterogeneity 
“(I2 = 97%, p-value = 0.00001)”, as shown in Figure 3. 
Publication bias was assessed using visual inspection. The 
funnel plot showed no evidence of  publication bias while 
rather than publication bias, two outliers indicated true 
heterogeneity, as shown in Figure 4.

Figure 3: Forest plot: reported odds ratio of  Efficacy of  Rapid Sequence Intubation in two groups

Figure 4: Funnel Plot: no evidence of  publication bias

First, Second, and Overall Attempt Tracheal 
Intubation Success Rate between VL and DL
Eighteen studies have reported the intubation success rate 
between VL and DL in the first attempt. The meta-analysis 
results identified no significant differences “(OR = 2.52, 
95% Confidence interval 0.83 to 7.67, p–value = 0.04)”, 
as shown in Figure 5. This implied that, in the VL group, 
the odds of  patients with a first attempt of  successful 
intubation, were higher than that of  the DL group. 

Moderately high significant heterogeneity was found “(I2 
= 95%, p-value = 0.00001)”. However, the result of  the 
success rate in the second attempt and the overall success 
rate showed no significant difference between VL and DL 
“(2nd Attempt; OR = 0.66, 95% CI; 0.39, 1.11, p-value = 
0.12)” and “(Overall attempt; OR = 2.33, 95% CI; 0.68, 
7.95, p–value = 0.18)” respectively. The funnel plot showed 
a symmetric visualization, which indicated no evidence of  
publication bias, as shown in Figure 6.



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Figure 5: Forest plot: reported an odds ratio of  first attempt (2.1.1), Second attempt (2.1.2), and overall attempt 
(2.1.3) intubation success rate in two groups

Figure 6: Funnel plot: no publication bias in the studies included in the success rate of  first-attempt intubation

Time of  Tracheal Intubation in Seconds between VL 
and DL
Five trials were included in the meta-analysis of  
intubation time. The results were insignificant with VL 
“(SMD = -0.03s (95% Confidence Interval -0.22s to 
0.42s), p–value = 0.75)” compared with DL. However, 

despite insignificant results, there was a reduction in 
incubation time in the VL group compared to the DL 
group. High heterogeneity was found among the studies 
“(I2 = 95%, p-value < 0.000)” as shown in Figure 7. The 
funnel plot showed a symmetric shape with no evidence 
of  publication bias, as shown in Figure 8.



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Figure 7: Forest plot: reported odds ratio of  time to intubation in seconds

Figure 8: Funnel plot of  included studies in the intubation time

Subgroup Complications of  Intubation
Subgroup analyses for the complications in intubation 
showed that the odds of  Hypotension, Dental Trauma 
(DT), Severe Desaturation (SD), and RF after RSI was 
higher in the DL group as compared to VL “(OR = 
3.20, 95% CI; 0.48; 21.10, p–value = 0.23), (Trauma; OR 

= 1.02, 95% Confidence interval 0.62 to 1.68, p–value 
= 0.93, I2 = 21%), (Severe Desaturation; OR = 0.69, 
95% Confidence Interval 0.47 to 1.03,p–value = 0.07) 
and (Respiratory Failure; OR = 0.69, 95% Confidence 
interval 0.43 to 1.09, p–value = 0.11)” as shown in 
Figure 9.

Figure 9: Forest plot of  cases with complications in intubations with Hypertension, Dental Trauma, Severe 
Desaturation and Respiratory Failure



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DISCUSSION 
This systematic review and meta-analysis have analyzed 
the efficacy of  VL and DL in RSI in ICU. The first meta-
analysis, a comparison of  VL over DL for RSI, was 
conducted, as shown in Figure 4. The results revealed no 
significant difference between the VL and DL techniques, 
implying that the DL technique was better in RSI than 
VL. In the last decade, DL was first introduced in RSI 
for providing control on rapid airway that served as a 
prevention for patients suffering from a full stomach 
or other risks of  pulmonary aspiration. However, the 
introduction of  VL was found to be more efficient than 
DL due to the attachment of  a camera at the tip of  the 
blade that could improve the visualization of  the glottis 
by assisting airway management in critically ill patients 
(Arulkumaran et al., 2018; Griesdale et al., 2012; Silverberg 
et al., 2015). In contrast, no significant difference between 
the two techniques has been found. Hence, a further and 
detailed meta-analysis with more clinical trials on the best 
techniques for RSI in the emergency setting has been 
required.
In the meta-analysis, a comparison of  the success rates in 
RSI attempts was conducted within the EU using VL and 
DL. The comparison showed that only the success rate 
of  the first attempt was significant and higher in the VL 
group with an Odds ratio of  2.13 and 95% Confidence 
interval; 1.05 – 4.35 favoring DL with high heterogeneity 
I2 = 95%, as shown in Figure 3 and Figure 4. Hence, VL 
had a success rate in the first attempt compared to DL, 
but no significant difference was found in the second and 
overall attempts (Ba, 2022).
The high heterogeneity was due to differences in laboratory 
settings or follow-up periods. The non-superiority of  VL 
over DL might be due to limited experience of  the physicians 
handling airway management in VL. Additionally, VL offers 
visual aids, its image quality may not always match the clarity 
of  DL, potentially leading to misinterpretations (Olatunji et 
al., 2024). Anatomical variations and technical limitations of  
VL systems further contribute to its comparable efficacy 
with DL (Kim et al., 2016).
In the systematic review, the time to achieve success 
in EI using VL compared to DL found a reduction in 
time to achieve success in VL compared to DL in the 
EU (SMD = -0.03s, 95% CI -0.22 – 0.16). The results 
implied that the average time to achieve a successful EI 
was lower in VL than in DL. The results were consistent 
with a clinical trial of  EI. In a study, despite a significant 
improvement in Cormack-Lehane grade of  glottis view, 
DL took a prolonged period to achieve success compared 
to VL (Janz et al., 2016). Conversely, another study found 
that the time to intubation was similar between the two 
groups (Sulser et al., 2016).
The systematic review also compared several 
complications arising from utilizing VL and DL. The 
results found that hypotension, DT, RF, and SD were 
moderately high in VL compared with DL. The results 
aligned with the previously published meta-analysis in 
which the complications were significantly increased 
in DL compared with VL (Ba, 2022). No evidence of  

publication bias has been found in the funnel plot of  the 
included studies which indicated that, VL has not been a 
preferable method for RSI in the EU (Merola et al., 2024). 

LIMITATIONS 
In acknowledging the scope of  meta-analysis, it is 
imperative to address certain limitations that might 
have influenced the systematic review’s findings. First, 
Selection Bias and High Heterogeneity were inevitably 
introduced when observational studies were included. 
Second, during the database search process, studies 
that were published in English only were included. As a 
result, pertinent, relevant controlled trials demonstrating 
advancements in VL may have been published in other 
languages, potentially enhancing the findings of  the 
systematic review and meta-analysis if  considered.

CONCLUSION 
In summary, the utilization of  VL in RSI has been 
linked to a reduced time to achieve successful intubation 
compared to DL. However, the effectiveness of  VL 
over DL remains modest. Therefore, further analysis, 
such as hospital duration of  stays, follow-up time, and 
monitoring of  adverse events, has been necessary for a 
thorough meta-analysis.

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