Anual assignment: Class 9

Regent: Prof. Doutor Altamiro da Costa Pereira

Orientator: Drª Cristina Santos

15/12/2005

What is the sensitivity and specificity of amniotic fluid

lamellar body count in detection of respiratory distress syndrome?

Introduction

What is amniocentesis?What is the use of this method?

What is a respiratory distress syndrome?

What is a test's sensitivity and specificity?

Why is this systematic review important?

What is the aim of this study?

What is amniocentesis?

Amniocentesis: is a percutaneous transabdominal puncture of the uterus during pregnancy to obtain amniotic fluid. It is commonly used for fetal karyotype determination in order to diagnose abnormal fetal conditions.

Pubmed research:”amniocentesis” [MeSH terms]GRAÇA, Luis Mendes da et al; Medicina materno-fetal; 3rd edition; Lidel Lisboa

What is the use of this method?

Amniocentesis is used to evaluate the lung maturity of the fetus;Throughout the lamellar body count in the amniotic fluid, it is possible to detect the respiratory distress syndrome.

Pubmed research:”amniocentesis” [MeSH terms]GRAÇA, Luis Mendes da et al; Medicina materno-fetal; 3rd edition; Lidel Lisboa

What is a respiratory distress syndrome?

Respiratory distress syndrome: Frequent in premature infants, children of diabetic

mothers and infants delivered by cesarean section; Syndrome of respiratory difficulty caused by a

deficiency of lung surfactant; Symptoms: dyspnea with cyanosis dilatation of the alae nasi expiratory grunt etc.

Possible treatments : extra oxygen(21%) CPAP (Continuous Positive Airway

Pressure) surfactant In last case the baby is intubated

Pubmed research:”respiratory distress syndrome” [MeSH terms]CUNNINGHAM, F.Gary et al ;William’s Obstetrics;22nd edition; Mc Graw-Hill; Medical Publishing Division; New York www.pedriatics.wisc.edu

What is a test's sensitivity and specificity?

Sensitivity and specificity are parameters that express something about the tests’ performance;

Sensitivity is the test ability to detect a disease when it is effectively present – true positives. If the babies suffer from respiratory distress syndrome, amniocentesis result is positive.

Specificity is the test ability to detect true negatives. If the babies are healthy, amniocentesis result is negative.

JECKEL, J et al; Epidemiology Biostatistics and preventive Medicine; W.R. Samders Text Company, 1996 TIMMCREEK, T. ; An Introduction to Epidemiology; Jones and Bontlett Publishers,1994Wikipedia

Why is this systematic review important?

Problem: There is some doubt about the sensitivity and specificity of amniocentesis in determination of respiratory distress syndrome

So... This systematic review allows the analysis of all articles about this topic on Pubmed till October 2005.This systematic review can provides to all health personnel reliable information about amniocentesis sensitivity and specificity.

What is the aim of this study?

The aim of our study is systematic review of all articles that evaluate the specificity and sensitivity of amniotic fluid lamellar body count in detection of respiratory distress syndrome.

Study DesignSystematic review with possible metanalysis

Steps of article:

1. Search for literature2. Use predifined Inclusion/Exclusion Criteria to select the

article3. Evaluate quality of articles4. Extract data5. Statistical analysis of data

Research methods

• Database: Medline• Limits: publications until 2005/10; Humans• The search and methods aimed at finding all the

evidence which could be useful in estimating the sensitivity and specificity of lamellar body count from the amniotic fluid in detection of respiratory distress syndrome in Newborn

Search PlanObjective:find articles related to diagnostic studies referring to the respiratory distress syndrome.

1.Find articles of all diagnostic studies2.Find articles of all diagnostic studies referring to amniotic

fluid3.Find articles of all diagnostic studies referring respiratory

distress syndrome, Newborn4.Find articles of all diagnostic studies related to lamellar

body count5.Gather all data

Search process1st step: Sensitity and Specificity

Using a recommended search strategy*

(sensitiv*[Title/Abstract] OR sensitivity and specificity[MeSH Terms] OR diagnos*[Title/Abstract] OR diagnosis[MeSH:noexp] OR diagnostic * [MeSH:noexp])

MeSH (Medical Headin Subject): sensitivity and specificity[MeSH Terms] ; diagnosis[MeSH:noexp ; diagnostic * [MeSH:noexp]

Search 1: N=1962714 articles Haynes RB, Wilczynski NC for the Hedges Team. Optimal search strategies for

retrieving scientifically strong studies of diagnosis from MEDLINE: analytical survey. BMJ. 2004 May 1;328(7447):1040

2nd Step: Amniotic fluid

Search: all diagnosis studies related to amniotic fluid.

MeSH terms: “Amniotic Fluid”

Search query: (search1) AND ("amniotic fluid "[Mesh])

N=12536 articles

3rd Step:

MeSH term: respiratory distress syndrome, Newborn [MeSH]

Query:(search1) AND ("respiratory distress syndrome, Newborn" [MeSH] OR "lung maturity" OR "respiratory distress syndrome" OR "FLM" OR “surfactant” OR “hyaline membrane”)

N= 26438 articles

4th step

Search: obtain diagnosis studies related to the given intervention, lamellar body count,

Query: (search1) AND ("lamellar body count" OR "lamellar bodies" )

N=454 articles

Final step:

Finally all previous searches were crossed in order to obtain the final number of articles

Query: (sensitiv*[Title/Abstract] OR sensitivity and specificity[MeSH Terms] OR diagnos*[Title/Abstract] OR diagnosis[MeSH:noexp] OR diagnostic * [MeSH:noexp] OR diagnosis,differential[MeSH:noexp] OR diagnosis[Subheading:noexp]) AND ("amniotic fluid" [MeSH]) AND ("respiratory distress syndrome, Newborn" [MeSH] OR "lung maturity" OR "respiratory distress syndrome" OR “surfactant” OR “hyaline membrane”) AND ("lamellar body count" OR "lamellar bodies" )

N=24 articles

Critics on research methods

It was only used Medline database, not having used other data source such as Cochrane central or manual research

Final search query may have been very specific

Pai M, McCullock M, Gorman JD, Pai N, Enanoria W, Kennedy G, Tharyan P, Colford

JM Jr. Systematic reviews and meta-analyses: Na illustrated, step-by-step guide. The National Medical Journal of India 2004; 17(2): 86-95

• 3 independent reviewers will read the titles and abstract selecting the articles according to the inclusion/exclusion criteria.

Title and abstract review

Criteria of Inclusion

The articles must refer to:

Sensitivity and specificity Diagnostic method of amniotic fluid lamellar body

count Amniocentesis in the detection of Respiratory DistressSyndrome Provides the desired outcome data (True Positives, true

Negatives, false positives, false negatives)

Criteria of exclusion

Studies which make reference to animals

All the articles that not obey to inclusion criteria

Accuracy and quality evaluation of the Articles

To evaluate the accuracy and quality of the articles according to the criteria of inclusion/exclusion, independent reviewers will use the “Standards for Reporting of Diagnostic Accuracy” (STARD) checklist.

Bossuyt, Patrick et all The STARD Initiative Towards Complete and Accurate Reporting of Studies of Diagnostic Accuracy Radiology 2003; 226:24–28

Flowchart

Research in the Medline using the

the research methods

ResultsN=24

Title and abstract screening according to inclusion/exclusion

criteria 3 independent reviwers

BeginningArticles Excluded

ResultsN=

Articles Included

Quest for full article review

Was the article found?

Article Excluded for

the Metanalysis

N=

No

Yes

Do the articles agree with the quality standards?Do the articles have sufficient data for the metanalysis?

Articles Included for the Metanalysis

N=

Yes

Articles Excluded for

the Metanalysis

N=

No

ResultsN=

Full Article Analysis based on the STARD Chacklist by 3 independet reviewers

The End

Data extraction

True Positives, True Negatives; False positives; False negativesValues of:

Sensitivity Specificity

Sample Size / Number of articlesCut-off pointsOutcome VariableConfidence Interval (95%)

Software used for input and analysis: metadisc

Data analysis

1. Presentation of the results of individual studies2. Searching for the presence of heterogeneity3. Testing of the presence of an (implicit) cut-point effect4. Dealing with heterogeneity5. Deciding which model should be used if statistical

pooling is appropriate6. Statistical pooling

Devillé, Walter et all - Conducting systematic reviews of diagnostic studies - Didactic guidelines; BMC Medical Research Methodology 2002, 2:9

Gantt chart