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For peer review only

Epidemiology of venous thromboembolism in Africa: a systematic review and meta-analysis protocol

Journal: BMJ Open

Manuscript ID bmjopen-2017-016223

Article Type: Protocol

Date Submitted by the Author: 01-Feb-2017

Complete List of Authors: Danwang, Celestin; Faculty of Medecine and Biomedical Sciences, Surgery and specialities Mazou, Temgoua Ngou ; Faculty of Medecine and Biomedical Sciences, Internal medicine and specialities Agbor, Ndip; Ibal sub-Divisional Hospital, General practice Tankeu, Aurel; Faculty of Medecine and Biomedical Sciences, Internal medicine and specialities Noubiap, Jean Jacques; Groote Schuur Hospital and University of Cape

Town, Medicine

<b>Primary Subject Heading</b>:

Cardiovascular medicine

Secondary Subject Heading: Public health

Keywords: Venous thromboembolism, deep venous thrombosis, pulmonary embolism, Africa

For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml

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1

Epidemiology of venous thromboembolism in Africa: a systematic review and meta-

analysis protocol

Celestin Danwang1†

, Mazou N. Temgoua2†

, Valirie Ndip Agbor3, Aurel T. Tankeu

2, Jean

Jacques N. Noubiap 4*

1. Department of Surgery and Specialties, Faculty of Medicine and Biomedical Sciences,

University of Yaoundé I, Yaoundé, Cameroon.

2. Department of Internal Medicine and Specialties, Faculty of Medicine and Biomedical

Sciences, University of Yaoundé I, Yaoundé, Cameroon

3. Ibal Sub-divisional Hospital, Oku, North West Region, Cameroon

4. Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape

Town, South Africa.

† Equal contributors

E-mail addresses: CD: [email protected]; TNM: [email protected]; VNA:

[email protected]; ATT: [email protected]; JJNN: [email protected]

*Corresponding author: Dr Jean Jacques N. Noubiap MD Department of Medicine, Groote

Schuur Hospital and University of Cape Town, Cape Town, South Africa.

E-mail: [email protected]

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Abstract

Introduction

Venous thromboembolism (VTE) is among the three most common causes of cardiovascular

diseases worldwide. Accurate data are necessary in order to evaluate the burden of this

condition and to design effective preventive strategies and management recommendations. In

Africa, little is known about the global epidemiology of this condition. This review aims to

determine the burden of VTE in Africa.

Methods and analysis

This systematic review and meta-analysis will include cross-sectional, case–control, case

series of at least 30 subjects and cohort studies of populations residing inside African

countries, which have reported data on prevalence/incidence of VTE in Africa. Only studies

which confirmed VTE using a Doppler ultrasonography and/or a pulmonary Contrast

Tomography (CT) scan will be considered for inclusion. We will search MEDLINE, Scopus

and African Journal online (AJOL) databases for relevant abstracts without language and date

restriction. Two review authors will independently screen, select studies, extract data and

assess the risk of bias in each study. Clinical and statistical heterogeneity will be assessed, and

we will pool studies judged to be clinically homogenous. Statistical heterogeneity will be

evaluated by the χ2 test on Cochrane’s Q statistic. Funnel-plots analysis and Egger’s test will

be used to detect publication bias. Results will be presented by geographic region (central,

eastern, northern, southern and western Africa). This systematic review will be reported

according to the MOOSE Guidelines for Meta-Analyses and Systematic Reviews of

Observational Studies.

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Ethics and dissemination

The current study will be based on published data, and thus ethics consideration is not

required. This review is expected to provide relevant data to help in quantifying the

magnitude of this disease in Africa. The final report of this study will be published in a peer-

reviewed journal and the findings will be submitted to relevant health authorities.

Review registration number: CRD42017056253

Keywords: Venous thromboembolism; deep venous thrombosis; pulmonary embolism;

Africa.

Strengths and limitations of the study

1. To the best of our knowledge, this will be the first systematic review and Meta-

Analyses on the topic of venous thromboembolism (VTE) to summarize available data

on African continent.

2. A major possible limitation of this study could be the limited data with predominance

of hospital-based studies. Indeed, these studies may not reflect the true

prevalence/incidence of VTE in the general population.

3. Another possible limitation may be heterogeneity of studies done on the topic in

Africa.

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Introduction

The recent increase in life-expectancy has led to an epidemiological transition from

communicable to non-communicable diseases worldwide (1). In this context, Africa is

currently facing a growing epidemic of non-communicable diseases among which

cardiovascular diseases (CVDs) remain the most frequent and murderous (2-3). In 2012, the

World Health Organization (WHO) estimated that 17.5 million people died from CVD, with

over three quarters occurring in low- and middle-income countries such as African countries

(4, 5). The increasing burden of CVD over the recent years has been mostly explained by the

increase in atheromatous diseases relegating others certainly less experienced CVDs but still

encountered such as venous thromboembolism (VTE) in the background. VTE which consists

of two main conditions: deep vein thrombosis (DVT) and pulmonary embolism (PE), is part

of the three most common causes of cardiovascular diseases worldwide (1). It is a life-

threatening condition associated with significant morbidity and mortality. Usually, VTE

occurs as a postoperative complication, affecting about 33% of patients undergoing an

elective general surgical procedure, but also complicates many medical conditions especially

in intensive care units (6). Thrombosis has various clinical presentations with different

consequences in depending on the size of the occluded vessel, the length, localization and

duration of obstruction. Among these locations, thrombosis of leg veins remains the most

frequent, while pulmonary embolism and deep pelvic venous thromboembolism (VTE) are

considered the most dangerous. Although many studies have evaluated the burden of VTE in

non-African populations such as: American, European or Asian patients, there is limited

evidence concerning epidemiology of this disease in Africa (7, 8). Herein, we seek to provide

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a comprehensive overview on the prevalence/incidence, mortality and prophylaxis of

published literature on VTE in African populations.

Objective

To conduct a systematic review and meta-analysis, with the aim to determine the prevalence,

incidence, mortality and prophylactic measures of VTE in Africa.

Review question

Specifically, we seek to answer the following questions

1. What are the prevalence and/or incidence of VTE among African populations?

2. What is the mortality related to pulmonary embolism (PE) in Africa?

3. What is the proportion of at-risk subjects receiving VTE prophylaxis in African?


Criteria for considering studies for the review

Inclusion criteria

All published observational studies (cross-sectional, case series with at least 30 participants,

case–control and cohort studies) until 05 December 2016 with sufficient data on: the

prevalence and/or incidence of VTE, mortality rate of PE and use of VTE prophylaxis in

African countries will be included without any language restrictions.

Exclusion criteria

We will not consider:

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1. Studies conducted among populations of African origin residing outside Africa;

2. Studies in which relevant data on VTE is impossible to extract;

3. Letters, reviews, commentaries and editorials;

4. Case series with < 30 participants;

5. Studies lacking key data and/or explicit method description;

6. Studies with inaccessible full-text even after request from the authors

7. Study duplicates: for studies published in more than one paper, the most comprehensive

one reporting the largest sample size will be considered.

Search strategy for identifying relevant studies

This systematic review will be reported according to MOOSE Guidelines for Meta-Analyses

and Systematic Reviews of Observational Studies (9). The search strategy will be devised in

two steps.

Bibliographic database searches

Firstly, relevant abstracts published on the prevalence, incidence, mortality and prophylaxis of

VTE in Africa will be identified via searching MEDLINE, Scopus and African Journal online

(AJOL) Database. The search will be done with no date or without language restriction. Both

text words and medical subject heading terms will be used related to VTE (see table 1). We

will also use individual country names for the 54 African countries as additional key search

terms for more abstracts on the subject.

Secondly, the abstracts of all eligible papers will be reviewed and full articles will be accessed

through PubMed, Scopus Database, AJOL, Google Scholar, HINARI, Sci Hub or journals’

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websites. Additionally, references of all relevant articles and reviews will be scrutinized for

other potential data sources, and their full texts will be accessed in a similar way. The authors

of papers whose full text cannot be obtained by the numerous internet-based sources will be

directly contacted to provide them. In case of no feedback from these authors, the

corresponding studies will be excluded.

Searching for others sources

The references of all relevant researches and review articles will be scrutinized for additional

potential data sources missed during the search of the MEDLINE database, and their full texts

will be accessed as detailed above.

Selection of studies for inclusion in the review

Two authors (DC and MNT) will independently assess eligible papers using an assessment

guide to ensure that the selection criteria are reliably applied by all the team. They will screen

the titles and abstracts obtained from the searches and the full texts of potentially eligible

papers will be retrieved by at least one author. Thereafter, they will independently review the

full text of each potentially eligible study, compare their results and resolve any discrepancy

by discussion and consensus. If a decision is not reached, a third review author (ATT) will be

consulted for arbitration.

Assessment of methodological quality and reporting of data

An adapted version of the Risk of Bias Tool for Prevalence Studies developed by Hoy et al

(10), will be used to evaluate included studies for quality and bias, and will be applied to

screened full-text articles. Assessment of the risk of selection and attrition bias will use the

Cochrane guidelines available in Review Manager V.5.3 (http://tech.cochrane.org/revman).

Furthermore, the reporting quality of each study will be assessed using the STROBE.

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Data extraction and management

A data extraction sheet will be used to collect information about the author, the country, the

year of publication, the study design, the sample size population, the mean or median age of

the population, the age range, the sex ratio, the prevalence/incidence of VTE as well as data

concerning prophylaxis and mortality of VTE when available. Where prevalence or

information for calculating them (e.g. sample size, number of outcomes) are lacking, we will

directly contact the corresponding author to request the information. In case of multinational

studies, we will separate the results to show the prevalence and etiologies within individual

countries. Where it will not be possible to disaggregate the data by country, the study will be

presented as one and the countries in which the study was done will be shown.

Data synthesis and analysis

Prevalence/incidence data will be summarized by country and geographic region (central,

eastern, northern, southern and western Africa). A meta-analysis will be conducted for

variables defined identically across studies. Standard errors (SEs) for the study-specific

estimates will be determined from the point estimate and the appropriate denominators,

assuming a binominal (or Poisson for incidence data) distribution. We will pool the study-

specific estimates using a random effects meta-analysis model to obtain an overall summary

estimate of the prevalence and/or incidence across studies, after stabilizing the variance of

individual studies with the use of the Freeman-Tukey double arc-sine transformation (11).

Heterogeneity will be assessed using the χ2 test on Cochrane’s Q statistic (12), and quantified

by calculating the I2 (13). Values of 25%, 50% and 75% for I

2 represent, respectively, low,

medium and high heterogeneity. We will assess the presence of publication bias using funnel

plots and Egger’s test (14). Where substantial heterogeneity is detected, we will perform

subgroup analysis to investigate the possible sources of heterogeneity using the following

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grouping variables: age group, sex, study setting (rural vs urban; hospital vs community-

based), geographical region (central, eastern, northern, southern and western Africa) and

study quality. We will assess inter-rater agreement for study inclusion using Cohen’s κ

coefficient (15). Data will be analyzed using Stata software version 13 (Stata Corp V.13,

Texas, USA).

Presentation and reporting of results

The study selection process will be summarized using a flow diagram. Reasons for exclusion

of studies will be described. This will follow the MOOSE Guidelines for Meta-Analyses and

Systematic Reviews of Observational Studies (9). Quantitative data will be presented in

evidence tables of individual studies as well as in summary tables and forest plots where

appropriate. We will determine prevalence/incidence and mortality rate as well as use of

prophylaxis, by region, country, setting (rural or urban), time period and disease-specific

populations depending on the data available. We plan to report on quality scores and risk of

bias for each eligible study. This may be tabulated and accompanied by narrative summaries.

Conclusion

Even though VTE is among the three most common causes of CVDs worldwide, little

attention seems to be paid on this disease in Africa. This is evident by a paucity of data on the

topic in the African literature. Therefore, it is crucial to provide summarized up-to-date and

reliable data on the epidemiology as well as mortality and the use of prophylaxis against VTE

in Africa in order to highlight the importance of this disease. We hope that this review will

help sensitize healthcare providers on the burden of VTE in Africa, assist and support the

implementation of new policies, practices and researches.

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Protocol and registration

The protocol for this review has been published in the PROSPERO International Prospective

Register of systematic reviews (http://www.crd.york.ac.uk/PROSPERO), registration number:

CRD42017056253

Authors’ Contributions

DC, MNT and JJNN conceived and designed the protocol. DC drafted the manuscript. TNM,

ATT, NAV and JJNN critically revised the manuscript for methodological and intellectual

content. JJNN is the guarantor of the review. All authors approved the final version of this

manuscript.

Competing interests

None.

Funding

This research received no specific grant from any funding agency in the public, commercial or

not-for-profit sectors.

Data sharing statement

No additional data are available.

References

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1. Raskob GE, Angchaisuksiri P, Blanco AN, Buller H, Gallus A, Hunt BJ, et al.

Thrombosis: a major contributor to global disease burden. Arterioscler Thromb Vasc

Biol. 2014 Nov;34(11):2363–71.

2. Mbewu A, Mbanya J-C. Cardiovascular Disease. In: Jamison DT, Feachem RG,

Makgoba MW, Bos ER, Baingana FK, Hofman KJ, et al., editors. Disease and

Mortality in Sub-Saharan Africa [Internet]. 2nd ed. Washington (DC): World Bank;

2006 [cited 2016 Mar 13]. Available from:

http://www.ncbi.nlm.nih.gov/books/NBK2294/

3. Reddy KS, Yusuf S. Emerging epidemic of cardiovascular disease in developing

countries. Circulation. 1998 Feb 17;97(6):596–601.

4. WHO. WHO CVD-risk management package for low-and medium-resource settings.

Geneva, Switzerland: World Heath Organization, 2002.

5. WHO | Cardiovascular diseases (CVDs) [Internet]. WHO. [Cited 2016 Mar 13].

Available from: http://www.who.int/entity/cardiovascular_diseases/en/index.html

6. Snyman LC, Potgieter J. Venous thromboembolism: Risk profile and management of

prophylaxis in gynaecological surgery patients. South Afr J Obstet Gynaecol. 2014

Oct 23;20(3):76.

7. Heit JA, Spencer FA, White RH. The epidemiology of venous thromboembolism. J

Thromb Thrombolysis. 2016 Jan;41(1):3–14.

8. Stroup DF, Berlin JA, Morton SC, Olkin I, Williamson GD, Rennie D, et al. Meta-

analysis of observational studies in epidemiology: a proposal for reporting. Meta-

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analysis Of Observational Studies in Epidemiology (MOOSE) group. JAMA. 2000

Apr 19;283(15):2008-12.

9. Hoy D, Brooks P, Woolf A, Blyth F, March L, Bain C, et al. Assessing risk of bias in

prevalence studies: modification of an existing tool and evidence of interrater

agreement. J Clin Epidemiol. 2012 Sep;65(9):934-9.

10. Barendregt JJ, Doi SA, Lee YY, Norman RE, Vos T. Meta-analysis of prevalence. J

Epidemiol Community Health. 2013 Nov 01;67(11):974-8.

11. Cochran WG. The combination of estimates from different experiments. Biometrics

1954;10:101 –29.

12. Higgins IP, Thompson SG. Quantifying heterogeneity in a meta-analysis. Stat Med

2002;21:1539–58.

13. Egger M, Davey Smith G, Schneider M, et al. Bias in meta-analysis detected by a

simple, graphical test. BMJ 1997;315:629–34.

14. Landis JR, Koch GG. The measurement of observer agreement for categorical data.

Biometrics 1977;33:159–74.

Table 1: Search strategy for PubMed

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Search Search terms

#1 Venous thromboembolism [tw] OR Venous thromboembolic disease[tw] Or

Deep vein thrombosis[tw] Or Pulmonary embolism[tw] OR Pulmonary

Thromboembolism[MeSH terms] OR Thromboembolism [MeSH terms]

#2 (Africa* OR Algeria OR Angola OR Benin OR Botswana OR "Burkina Faso"

OR Burundi OR Cameroon OR "Canary Islands" OR "Cape Verde" OR

"Central African Republic" OR Chad OR Comoros OR Congo OR

"Democratic Republic of Congo" OR Djibouti OR Egypt OR "Equatorial

Guinea" OR Eritrea OR Ethiopia OR Gabon OR Gambia OR Ghana OR

Guinea OR "Guinea Bissau" OR "Ivory Coast" OR "Cote d'Ivoire" OR

Jamahiriya OR Kenya OR Lesotho OR Liberia OR Libya OR Madagascar

OR Malawi OR Mali OR Mauritania OR Mauritius OR Mayotte OR Morocco

OR Mozambique OR Namibia OR Niger OR Nigeria OR Principe OR

Reunion OR Rwanda OR "Sao Tome" OR Senegal OR Seychelles OR "Sierra

Leone" OR Somalia OR "South Africa" OR “South Sudan” OR "St Helena"

OR Sudan OR Swaziland OR Tanzania OR Togo OR Tunisia OR Uganda OR

"Western Sahara" OR Zaire OR Zambia OR Zimbabwe OR "Central Africa"

OR "Central African" OR "West Africa" OR "West African" OR "Western)

Africa" OR "Western African" OR "East Africa" OR "East African" OR

"Eastern Africa" OR "Eastern African" OR "North Africa" OR "North

African" OR "Northern Africa" OR "Northern African" OR "South African"

OR "Southern Africa" OR "Southern African" OR "sub Saharan Africa" OR

"sub Saharan African" OR "subSaharan Africa" OR "subSaharan African")

NOT ("guinea pig" OR "guinea pigs" OR "aspergillus niger")

#3 #1 AND #2

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PRISMA-P (Preferred Reporting Items for Systematic review and Meta-Analysis Protocols) 2015 checklist: recommended items to

address in a systematic review protocol*

Section and topic Item No Checklist item

ADMINISTRATIVE INFORMATION

Title:

Identification 1a Identify the report as a protocol of a systematic review (Pg. 01)

Update 1b If the protocol is for an update of a previous systematic review, identify as such (N/A)

Registration 2 If registered, provide the name of the registry (such as PROSPERO) and registration number (PROSPERO

International Prospective Register of systematic reviews; registration number: CRD42017056253)

Authors:

Contact 3a Provide name, institutional affiliation, e-mail address of all protocol authors; provide physical mailing address of

corresponding author (Pg. 1)

Contributions 3b Describe contributions of protocol authors and identify the guarantor of the review (Pg. 10)

Amendments 4 If the protocol represents an amendment of a previously completed or published protocol, identify as such and list changes;

otherwise, state plan for documenting important protocol amendments (N/A)

Support:

Sources 5a Indicate sources of financial or other support for the review (N/A)

Sponsor 5b Provide name for the review funder and/or sponsor (N/A)

Role of sponsor or funder 5c Describe roles of funder(s), sponsor(s), and/or institution(s), if any, in developing the protocol (N/A)

INTRODUCTION

Rationale 6 Describe the rationale for the review in the context of what is already known (Pg. 04)

Objectives 7 Provide an explicit statement of the question(s) the review will address with reference to participants, interventions,

comparators, and outcomes (PICO) (Pg. 05)

METHODS

Eligibility criteria 8 Specify the study characteristics (such as PICO, study design, setting, time frame) and report characteristics (such as years

considered, language, publication status) to be used as criteria for eligibility for the review (Pg. 05)

Information sources 9 Describe all intended information sources (such as electronic databases, contact with study authors, trial registers or other

grey literature sources) with planned dates of coverage (Pg. 06)

Search strategy 10 Present draft of search strategy to be used for at least one electronic database, including planned limits, such that it could be

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repeated (Pg. 12)

Study records:

Data management 11a Describe the mechanism(s) that will be used to manage records and data throughout the review (Pg. 078

Selection process 11b State the process that will be used for selecting studies (such as two independent reviewers) through each phase of the

review (that is, screening, eligibility and inclusion in meta-analysis) (Pg. 07)

Data collection process 11c Describe planned method of extracting data from reports (such as piloting forms, done independently, in duplicate), any

processes for obtaining and confirming data from investigators (Pg. 08)

Data items 12 List and define all variables for which data will be sought (such as PICO items, funding sources), any pre-planned data

assumptions and simplifications (Pg. 08)

Outcomes and prioritization 13 List and define all outcomes for which data will be sought, including prioritization of main and additional outcomes, with

rationale (N/A)

Risk of bias in individual studies 14 Describe anticipated methods for assessing risk of bias of individual studies, including whether this will be done at the

outcome or study level, or both; state how this information will be used in data synthesis (Pg. 07)

Data synthesis 15a Describe criteria under which study data will be quantitatively synthesised (Pg. 08)

15b If data are appropriate for quantitative synthesis, describe planned summary measures, methods of handling data and

methods of combining data from studies, including any planned exploration of consistency (such as I2, Kendall’s τ) (Pg. 09)

15c Describe any proposed additional analyses (such as sensitivity or subgroup analyses, meta-regression) (Pg. 08 and 09)

15d If quantitative synthesis is not appropriate, describe the type of summary planned (Pg. 09)

Meta-bias(es) 16 Specify any planned assessment of meta-bias(es) (such as publication bias across studies, selective reporting within studies)

(Pg. 08)

Confidence in cumulative evidence 17 Describe how the strength of the body of evidence will be assessed (such as GRADE)

* It is strongly recommended that this checklist be read in conjunction with the PRISMA-P Explanation and Elaboration (cite when available) for important

clarification on the items. Amendments to a review protocol should be tracked and dated. The copyright for PRISMA-P (including checklist) is held by the

PRISMA-P Group and is distributed under a Creative Commons Attribution Licence 4.0.

From: Shamseer L, Moher D, Clarke M, Ghersi D, Liberati A, Petticrew M, Shekelle P, Stewart L, PRISMA-P Group. Preferred reporting items for systematic review and

meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation. BMJ. 2015 Jan 2;349(jan02 1):g7647.

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Journal: BMJ Open

Manuscript ID bmjopen-2017-016223.R1


Date Submitted by the Author: 02-Jun-2017


Town, Medicine






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analysis protocol




2, Jean

Jacques N. Noubiap 4*





3. Ibal Sub-divisional Hospital, Oku, North West Region, Cameroon


Town, South Africa.


E-mail addresses: CD: [email protected]; MNT: [email protected]; VNA:

[email protected]; ATT: [email protected]; JJNN: [email protected]



E-mail: [email protected]. Phone: +27738036352

Protocol and registration: The protocol for this review has been published in the

PROSPERO International Prospective Register of systematic reviews

(http://www.crd.york.ac.uk/PROSPERO), registration number: PROSPERO

CRD42017056253.

Authors’ Contributions: CD, MNT and JJNN conceived and designed the protocol. CD

drafted the manuscript. MNT, ATT, VNA and JJNN critically revised the manuscript for

methodological and intellectual content. JJNN is the guarantor of the review. All authors

approved the final version of this manuscript.

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Abstract

Introduction

Venous thromboembolism (VTE) is among the three major causes of CVDs worldwide after

ischemic heart disease and stroke. Very little is known about the global epidemiology of this

condition in Africa. Accurate data are needed to evaluate the burden of VTE in Africa, in

order to design effective preventive and treatment strategies. This systematic review and

meta-analysis aims to summarize epidemiological data on VTE in Africa, and to evaluate the

use of prophylaxis in African patients at risk of VTE.


We will search MEDLINE, EMBASE, Scopus and African Journal online for relevant

abstracts of studies published between January 1st, 1986 and December 5

th 2016, without

language restriction. After a screening of abstracts, study selection, data extraction and

assessment of the risk of bias, we shall assess studies individually for clinical and statistical

heterogeneity. Appropriate meta-analytic technics will then be used to pool studies judged to

be clinically homogenous. Funnel-plots analysis and Egger’s test will be used to detect

publication bias. Results will be presented by geographic region (Central, Eastern, Northern,

Southern and Western Africa). This systematic review will be reported according to the

MOOSE Guidelines for Meta-Analyses and Systematic Reviews of Observational Studies.






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Africa.


1. To the best of our knowledge, this will be the first systematic review and Meta-

Analyses on VTE to summarize available data on African continent.

2. A limited amount of data with predominance of hospital-based studies pose as a major

restriction to this study, as the result may not reflect the true burden of VTE in the

general African population.


Africa.

Introduction


communicable to non-communicable diseases worldwide (1). As a result, Africa faces a

growing epidemic of non-communicable diseases among which cardiovascular diseases

(CVDs) remain the most frequent and a major cause of disease-associated mortality (2-3). In

2012, the World Health Organization (WHO) estimated that CVDs were responsible for 17.5

million deaths globally, with over three quarters occurring in low- and middle-income

countries, such as those in Africa (4, 5). Although the increasing burden of CVDs in recent

years has been attributed to an increase in the prevalence of atheromatous diseases, venous

thromboembolic diseases (VTDs) still remain a major cause of CVD burden. VTDs englobe

two main entities: deep vein thrombosis (DVT) and pulmonary embolism (PE); and is among

the three major causes of CVDs worldwide after ischemic heart disease and stroke (6). VTD

is a life-threatening condition associated with significant morbidity and mortality. Usually,

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DVT and PE occur as postoperative complications, affecting about 33% of patients

undergoing an elective general surgical procedure (7). Nevertheless, it complicates many

medical conditions especially in patients admitted to the intensive care unit (7). VTDs have

various clinical presentations, and the disease severity depends on the size of the occluded

vessel, the length, location and duration of obstruction. Among these locations, DVT of leg

veins remains the most frequent, while PE and thrombosis of deep pelvic veins are considered

the most common cause of death (6). Although many studies have evaluated the burden of

VTE in populations such as the American, European and Asian population, there is still a

dearth of evidence on the epidemiology of VTE in the African population (8). This review

seeks to provide a comprehensive overview of epidemiological data, and the use of

prophylaxis of published literature on VTE in African populations.

Objective



Review questions

Specifically, this review seek to answer the following questions


2. What is the mortality related to PE in Africa?

3. What is the proportion of subjects at risk receiving VTE prophylaxis in African?


This systematic review and meta-analysis protocol has been reported according to MOOSE

Guidelines for Meta-Analyses and Systematic Reviews of Observational Studies (9).

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Inclusion criteria

1. All observational studies (cross-sectional, case-series with at least 30 participants, case–

control and cohort studies)

2. Published between January 1st, 1986 and December 5

th 2016

3. Observational studies with sufficient data on: the prevalence and/or incidence of VTE,

mortality rate of PE and use of VTE prophylaxis in African countries will be included

without any language restrictions

4. Studies published in English or French.

Exclusion criteria


1. Studies conducted among populations of African origin residing outside Africa

2. Studies in which relevant data on VTE is lacking or impossible to extract

3. Letters, reviews, commentaries and editorials

6. Studies with inaccessible full text either online or from the corresponding author

7. For duplicates of studies published in more than report, the most comprehensive one

reporting the largest sample size will be considered.


The search strategy will be devised in two steps.


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Relevant studies published on VTE in Africa will be searched via MEDLINE, EMBASE,

Scopus and African Journal online (AJOL) databases from January 1st, 1986 to December 5

th

2016, with no language restriction. Both text words and medical subject heading terms related

to VTE will be used (table 1). The individual country names for the 54 African countries will

be used as additional key search terms to increase the sensitivity of our search (10).

Secondly, the abstracts of all eligible articles will be reviewed and full-text articles will be

accessed through PubMed, EMBASE, Scopus Database, AJOL, Google Scholar, HINARI,

Sci Hub or journals’ websites. The authors of papers whose full-text cannot be obtained by

the numerous internet-based sources will be directly contacted to provide them.


The references of all relevant articles and reviews will be scrutinized for additional data

sources missed during our search, and their full-texts will be retrieved as detailed above.


Two authors (CD and MNT) will independently assess eligible papers using an assessment

guide to ensure that the selection criteria are reliably applied by all the team. These authors

will carefully screen the titles and abstracts of papers obtained from the search, after which

the full texts of potentially eligible papers will be retrieved by at least one author. Thereafter,

they will independently review the full text of each potentially eligible study, compare their

results and resolve any discrepancy by discussion and consensus. If a decision is not reached,

a third review author (ATT) will be consulted for arbitration.


An adapted version of the Risk of Bias Tool for Prevalence Studies developed by Hoy et al (

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11), will be used to evaluate included studies for quality and bias, and will be applied to





A data extraction sheet will be used to collect information on the last name of the first author,

year of publication, Region (Central, Eastern, Northern, Southern and Western Africa),

Country, study design, study area (rural versus urban), study setting (population-based versus

hospital based), sample size, mean or median age, age range and male prevalence, disease

specific to the study population (cirrhotic patients, patients with tuberculosis, pregnant and

post-partum women and post-operative patients), the total number of cases of VTE, number of

new cases and/or number of deaths due to VTE in the study population. We shall report data

on DVT and PE separately. Data on the number of patients at risk of VTE who did or did not

receive prophylaxis for VTE will be extracted. For multinational studies, the prevalence,

incidence or mortality will be reported for the individual countries. Where it is impossible to

disaggregate data of multinational studies by country, the study will be presented as one and

the countries in which the study was done will be highlighted.


After data collection, a meta-analysis will be conducted for identical variables. Standard

errors for the study-specific estimates will be determined from the point estimate and the

appropriate denominators, assuming a binominal (or Poisson for incidence data) distribution.

The study-specific estimates will be pooled the using a random effects meta-analysis model to

obtain an overall summary estimate of the prevalence and/or incidence across studies, after

stabilizing the variance of individual studies with the use of the Freeman-Tukey double arc-

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sine transformation (12). Heterogeneity will be assessed using the χ2 test on Cochrane’s Q

statistic (13), and quantified by calculating the I2 (14). Values of 25%, 50% and 75% for I

2

represent, respectively, low, medium and high heterogeneity. We will assess the presence of

publication bias using funnel plots and Egger’s test (15). Where substantial heterogeneity is

detected, a subgroup analysis will be performed to investigate the possible sources of

heterogeneity using the aforementioned variables and the study quality. In case of substantial

heterogeneity, a narrative summary of our findings will be done. The inter-rater agreement for

study inclusion will be assessed using Cohen’s κ coefficient (16). Data will be analyzed using

Stata software version 13 (Stata Corp V.13, Texas, USA).


The study selection process will be summarized using a flow diagram. Quantitative data will

be presented in evidence tables for individual studies as well as in summary tables and forest

plots where appropriate. The quality scores and risk of bias for each eligible study will be

reported accordingly. This will be tabulated and accompanied by narrative summaries. This

may probably demonstrate a high incidence, prevalence and morbidity of VTE in Africa, and

a reduced use available methods of VTE prophylaxis.

Conclusion

Even though VTE is associated with significant mortality in low- and middle-income

countries, the impact of this condition on Africa remains obscure. It is therefore crucial to

provide summarized, up-to-date and reliable data on the epidemiology and the use of

prophylaxis against VTE in Africa in order to highlight the importance of this disease. We

hope that this review will help sensitize healthcare providers on the burden of VTE in Africa,

assist and support the implementation of new policies, practices and pave the way for new

researches.

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Competing interests

None.

Funding



Data sharing statement

No additional data are available.

References

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Med 2014; 370:1753-1755.

2. Mbewu A, Mbanya J-C. Cardiovascular Disease. In: Jamiso n DT, Feachem RG,


Mortality in Sub-Saharan Africa [Internet]. 2nd ed. Washington (DC): World Bank




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Geneva, Switzerland: World Heath Organization 2002.

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6. ISTH Steering Committee for World Thrombosis. Thrombosis: a major contributor to

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1954;10:101-29.

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Search Search terms
























#3 #1 AND #2

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Title:





Authors:






Support:




INTRODUCTION




METHODS






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repeated (Pg. 12)

Study records:









rationale (N/A)









(Pg. 08)







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Journal: BMJ Open





Town, Medicine






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j.com/

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ownloaded from



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analysis protocol




2, Jean

Jacques Noubiap 4*





3. Ibal sub-divisional Hospital, Oku, North West Region, Cameroon


Town, South Africa.



[email protected]; ATT: [email protected]; JJN: [email protected]



E-mail: [email protected]. Phone: +27738036352

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Abstract

Introduction










th 2016, without













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CRD42017056253.


Africa.


1. To the best of our knowledge, this will be the first systematic review and meta-

analysis to summarize available data on venous thromboembolism (VTE) on the

African continent.





Africa.

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Introduction



















the most common cause of death (6). Although many studies have evaluated the burden of

VTE in populations such as the American, European and Asian population, there is still a

dearth of evidence on the epidemiology of VTE in the African population (8). This review

seeks to provide a comprehensive overview of epidemiological data, and the use of

prophylaxis of published literature on VTE in African populations.

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Objective



Review questions






This protocol is written in accordance with recommendations from the Preferred Reporting

Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) 2015 statement (9).


Inclusion criteria




th 2016





Exclusion criteria

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th









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2









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References


Med 2014; 370:1753-1755.
















2014;20:76.



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9. Shamseer L, Moher D, Clarke M, Ghersi D, Liberati A, Petticrew M, Shekelle P,

Stewart LA; PRISMA-P Group. Preferred reporting items for systematic review and

meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation. BMJ. 2015

Jan 2;349:g7647. doi: 10.1136/bmj.g7647.



sensitivity and precision. Health Info Libr J 2011;28:210–5.



2012;65:934-9.


1978;32:138.


1954;10:101-29.

14. Huedo-Medina TB, Sanchez-Meca J, Marin-Martinez F, et al. Assessing heterogeneity

in meta-analysis: q statistic or I2 index? Psychol Methods 2006; 11:193-206.




82.

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Authors’ Contributions: JJN, CD and MNT and conceived and designed the protocol. CD

drafted the manuscript. MNT, ATT, VNA and JJN critically revised the manuscript for

methodological and intellectual content. JJN is the guarantor of the review. All authors


Competing interests

None.

Funding



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Search Search terms
























#3 #1 AND #2

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Title:





Authors:






Support:




INTRODUCTION




METHODS






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repeated (Pg. 12)

Study records:









rationale (N/A)









(Pg. 08)







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Journal: BMJ Open





Town, Medicine






BMJ Open on A


http://bmjopen.bm

j.com/

BM



ownloaded from



1


analysis protocol




2, Jean

Jacques Noubiap4*





3. Ibal sub-divisional Hospital, Oku, North West Region, Cameroon


Town, South Africa.



[email protected]; ATT: [email protected]; JJN: [email protected]

*Corresponding author: Dr Jean Jacques N. Noubiap, MD. Department of Medicine, Groote


E-mail: [email protected]. Phone: +27 73 803 6352

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Abstract

Introduction










th 2016, without













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CRD42017056253.


Africa.


1. To the best of our knowledge, this will be the first systematic review and meta-

analysis to summarize available data on venous thromboembolism (VTE) on the

African continent.





Africa.

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Introduction



















the most common cause of death (6). Some previous systematic reviews have evaluated the

burden of VTE in various populations including the general population (8) and in patients

with various medical conditions such as autoimmune diseases (9-12), liver disease(13), heart

failure(14), diabetes mellitus (15,16), cancer (17), post-hematopoietic stem cell

transplantation(18), post-surgery (19) and during pregnancy (20,21). However, all these

reviews summarized data mostly from populations outside Africa. As African populations

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differ from those of the rest of the world by their genetic background, specific living

conditions in Africa including limited access to medical care, diagnosis and preventive

interventions for VTDs, the burden of VTE might be different in African populations. Hence,

this review seeks to provide a comprehensive overview of epidemiology of VTE and its

prophylaxis in African populations.

Objective



Review questions






This protocol is written in accordance with recommendations from the Preferred Reporting

Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) 2015 statement (22).


Inclusion criteria



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th 2016





Exclusion criteria













th




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2





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References


Med 2014; 370:1753-1755.
















2014;20:76.



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82.

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Authors’ Contributions: JJN, CD and MNT and conceived and designed the protocol. CD

drafted the manuscript. MNT, ATT, VNA and JJN critically revised the manuscript for

methodological and intellectual content. JJN is the guarantor of the review. All authors


Competing interests

None.

Funding



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Search Search terms
























#3 #1 AND #2

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Title:





Authors:






Support:




INTRODUCTION




METHODS






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repeated (Pg. 12)

Study records:









rationale (N/A)









(Pg. 08)







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When an article is published we post the peer …...Celestin Danwang1†, Mazou N. Temgoua2 †,...

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Transcript of When an article is published we post the peer …...Celestin Danwang1†, Mazou N. Temgoua2 †,...