This is an excellent and crucial step for your systematic review! Adapting PICO for diagnostic accuracy questions is key to a well-defined search and clear review objectives.

1) PICO Format Adapted for Diagnostic Accuracy Questions

For diagnostic accuracy studies, the "C" (Comparator) is usually the Reference Standard or "Gold Standard" test, and the "O" (Outcome) specifically refers to measures of diagnostic accuracy. We'll also often add "S" for Study Design.

Your PICO (Adapted for Diagnostic Accuracy):

• P (Population/Patients): Patients suspected of having a specific infectious disease or conditions that warrant testing for a specific infectious disease.


• Example: Adult patients presenting with fever in malaria-endemic areas.


• Example: Individuals undergoing routine screening for HIV.


• Example: Patients with respiratory symptoms suspected of having influenza or COVID-19.


• I (Index Test/Intervention): The Rapid Diagnostic Test (RDT) being evaluated for its diagnostic performance.


• Example: Malaria antigen-detecting rapid diagnostic tests (Ag-RDTs).


• Example: HIV self-tests (oral fluid or blood-based).


• Example: SARS-CoV-2 antigen rapid diagnostic tests.


• C (Comparator/Reference Standard): The established "gold standard" or best available reference test against which the RDT's accuracy is measured.


• Example: Thick and thin blood smear microscopy (for malaria).


• Example: Laboratory-based enzyme immunoassay (EIA) confirmed by Western blot or nucleic acid test (NAT) (for HIV).


• Example: Reverse transcription polymerase chain reaction (RT-PCR) (for SARS-CoV-2 or influenza).


• O (Outcome): Measures of diagnostic accuracy.


• Specific measures: Sensitivity, Specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV), Likelihood Ratios (Positive LR, Negative LR), Diagnostic Odds Ratio (DOR), Area Under the Receiver Operating Characteristic (ROC) curve (AUC).


• S (Study Design - Optional but Recommended): Types of studies included.


• Specific design: Diagnostic accuracy studies, cross-sectional studies, cohort studies (where the index test and reference standard are applied to the same participants).

Crucial Note: You MUST narrow down the "specific infectious disease" for your review to be manageable and meaningful. A systematic review on all RDTs for all infectious diseases would be impossible to conduct.

2) Search Strategy for PubMed/MEDLINE, Embase, and Cochrane Library

Below is a comprehensive search strategy broken down by concept. You will combine these concepts using Boolean operators (AND, OR). Remember to adapt for specific database syntax and controlled vocabulary (MeSH for PubMed, Emtree for Embase).

General Principles:

• Use OR within each concept group to broaden your search for that concept.


• Use AND between concept groups to combine them and narrow your search to relevant studies.


• Use for truncation to capture variations (e.g., diagnos will find diagnosis, diagnose, diagnostic).


• Use [tiab] for PubMed/MEDLINE or :ab,ti for Embase to search in Title and Abstract fields.

Concept 1: Population / Infectious Disease (SPECIFY YOUR DISEASE HERE!)

This is where you'll define your specific infectious disease.

Example for Malaria:

• PubMed/MEDLINE (MeSH & Keywords):


• ("Malaria"[Mesh] OR "malaria"[tiab] OR "Plasmodium"[tiab])


• Embase (Emtree & Keywords):


• ('malaria'/exp OR malaria:ab,ti OR plasmodium:ab,ti)


• Cochrane Library (MeSH & Keywords):


• ("Malaria"[MeSH] OR malaria:ti,ab OR Plasmodium:ti,ab)

• PubMed/MEDLINE (MeSH & Keywords):


• ("COVID-19"[Mesh] OR "COVID 19"[tiab] OR "SARS-CoV-2"[Mesh] OR "SARS-CoV-2"[tiab] OR "coronavirus disease 19"[tiab])


• Embase (Emtree & Keywords):


• ('covid-19'/exp OR covid-19:ab,ti OR 'sars cov 2'/exp OR sars-cov-2:ab,ti OR 'coronavirus disease 19':ab,ti)


• Cochrane Library (MeSH & Keywords):


• ("COVID-19"[MeSH] OR COVID-19:ti,ab OR "SARS-CoV-2"[MeSH] OR SARS-CoV-2:ti,ab)

Concept 2: Index Test (Rapid Diagnostic Tests)

• PubMed/MEDLINE (MeSH & Keywords):


• ("Rapid Diagnostic Test"[Mesh] OR "Point-of-Care Systems"[Mesh] OR "rapid diagnostic test"[tiab] OR "RDT"[tiab] OR "point of care test"[tiab] OR "POCT"[tiab] OR "lateral flow"[tiab] OR "immunochromatographic"[tiab] OR "antigen test"[tiab] OR "antibody test"[tiab] OR "near patient test"[tiab] OR "bedside test"[tiab] OR "dipstick"[tiab] OR "strip test"[tiab] OR "quick test*"[tiab])


• Embase (Emtree & Keywords):


• ('rapid diagnostic test'/exp OR 'point of care system'/exp OR rapid diagnostic test:ab,ti OR RDT:ab,ti OR point of care test:ab,ti OR POCT:ab,ti OR lateral flow:ab,ti OR immunochromatographic:ab,ti OR antigen test:ab,ti OR antibody test:ab,ti OR near patient test:ab,ti OR bedside test:ab,ti OR dipstick:ab,ti OR strip test:ab,ti OR quick test*:ab,ti)


• Cochrane Library (MeSH & Keywords):


• ("Rapid Diagnostic Test"[MeSH] OR "Point-of-Care Systems"[MeSH] OR rapid diagnostic test:ti,ab OR RDT:ti,ab OR point of care test:ti,ab OR POCT:ti,ab OR lateral flow:ti,ab OR immunochromatographic:ti,ab OR antigen test:ti,ab OR antibody test:ti,ab OR near patient test:ti,ab OR bedside test:ti,ab OR dipstick:ti,ab OR strip test:ti,ab OR quick test*:ti,ab)

Concept 3: Outcome (Diagnostic Accuracy Measures)

• PubMed/MEDLINE (MeSH & Keywords):


• ("Diagnostic Accuracy"[Mesh] OR "Sensitivity and Specificity"[Mesh] OR "Predictive Value of Tests"[Mesh] OR "accuracy"[tiab] OR "accurate"[tiab] OR "sensitivity"[tiab] OR "specificity"[tiab] OR "predictive value"[tiab] OR "likelihood ratio"[tiab] OR "ROC curve"[tiab] OR "AUC"[tiab] OR "diagnostic performance"[tiab] OR "diagnosis"[tiab] OR "diagnos"[tiab] OR "false positive"[tiab] OR "false negative"[tiab])


• Embase (Emtree & Keywords):


• ('diagnostic accuracy'/exp OR 'sensitivity and specificity'/exp OR 'predictive value'/exp OR accuracy:ab,ti OR accurate:ab,ti OR sensitivity:ab,ti OR specificity:ab,ti OR predictive value:ab,ti OR likelihood ratio:ab,ti OR ROC curve:ab,ti OR AUC:ab,ti OR diagnostic performance:ab,ti OR diagnosis:ab,ti OR diagnos:ab,ti OR false positive:ab,ti OR false negative:ab,ti)


• Cochrane Library (MeSH & Keywords):


• ("Diagnostic Accuracy"[MeSH] OR "Sensitivity and Specificity"[MeSH] OR "Predictive Value of Tests"[MeSH] OR accuracy:ti,ab OR accurate:ti,ab OR sensitivity:ti,ab OR specificity:ti,ab OR predictive value:ti,ab OR likelihood ratio:ti,ab OR ROC curve:ti,ab OR AUC:ti,ab OR diagnostic performance:ti,ab OR diagnosis:ti,ab OR diagnos:ti,ab OR false positive:ti,ab OR false negative:ti,ab)

Concept 4: Study Type (Optional but can help refine)

This aims to identify diagnostic accuracy studies directly.

• PubMed/MEDLINE (Publication Type & Keywords):


• ("Diagnostic Test Accuracy Study"[pt] OR "Cross-Sectional Studies"[Mesh] OR "diagnostic accuracy study"[tiab] OR "test performance study"[tiab] OR "validation study"[tiab] OR "screening test"[tiab] OR "diagnosis study"[tiab] OR "sensitivity specificity study"[tiab])


• Embase (Emtree & Keywords):


• ('diagnostic accuracy study'/exp OR 'cross-sectional study'/exp OR diagnostic accuracy study:ab,ti OR test performance study:ab,ti OR validation study:ab,ti OR screening test:ab,ti OR diagnosis study:ab,ti OR sensitivity specificity study:ab,ti)


• Cochrane Library (Publication Type & Keywords):


• ("Diagnostic Test Accuracy Study"[pt] OR "Cross-Sectional Studies"[MeSH] OR diagnostic accuracy study:ti,ab OR test performance study:ti,ab OR validation study:ti,ab OR screening test:ti,ab OR diagnosis study:ti,ab OR sensitivity specificity study:ti,ab)

Putting It All Together (Example for Malaria RDTs):

PubMed/MEDLINE:

( ("Malaria"[Mesh] OR "malaria"[tiab] OR "Plasmodium"[tiab]) )
AND
( ("Rapid Diagnostic Test"[Mesh] OR "Point-of-Care Systems"[Mesh] OR "rapid diagnostic test*"[tiab] OR "RDT*"[tiab] OR "point of care test*"[tiab] OR "POCT"[tiab] OR "lateral flow"[tiab] OR "immunochromatographic"[tiab] OR "antigen test*"[tiab] OR "antibody test*"[tiab] OR "near patient test*"[tiab] OR "bedside test*"[tiab] OR "dipstick"[tiab] OR "strip test*"[tiab] OR "quick test*"[tiab]) )
AND
( ("Diagnostic Accuracy"[Mesh] OR "Sensitivity and Specificity"[Mesh] OR "Predictive Value of Tests"[Mesh] OR "accuracy"[tiab] OR "accurate"[tiab] OR "sensitivity"[tiab] OR "specificity"[tiab] OR "predictive value*"[tiab] OR "likelihood ratio*"[tiab] OR "ROC curve*"[tiab] OR "AUC"[tiab] OR "diagnostic performance"[tiab] OR "diagnosis"[tiab] OR "diagnos*"[tiab] OR "false positive*"[tiab] OR "false negative*"[tiab]) )
AND
( ("Diagnostic Test Accuracy Study"[pt] OR "Cross-Sectional Studies"[Mesh] OR "diagnostic accuracy study*"[tiab] OR "test performance study*"[tiab] OR "validation study*"[tiab] OR "screening test*"[tiab] OR "diagnosis study*"[tiab] OR "sensitivity specificity study*"[tiab]) )

Embase: (Note: Embase often allows direct combination without as many parentheses, but it's good practice to group)

( ('malaria'/exp OR malaria:ab,ti OR plasmodium:ab,ti) )
AND
( ('rapid diagnostic test'/exp OR 'point of care system'/exp OR rapid diagnostic test*:ab,ti OR RDT*:ab,ti OR point of care test*:ab,ti OR POCT:ab,ti OR lateral flow:ab,ti OR immunochromatographic:ab,ti OR antigen test*:ab,ti OR antibody test*:ab,ti OR near patient test*:ab,ti OR bedside test*:ab,ti OR dipstick:ab,ti OR strip test*:ab,ti OR quick test*:ab,ti) )
AND
( ('diagnostic accuracy'/exp OR 'sensitivity and specificity'/exp OR 'predictive value'/exp OR accuracy:ab,ti OR accurate:ab,ti OR sensitivity:ab,ti OR specificity:ab,ti OR predictive value*:ab,ti OR likelihood ratio*:ab,ti OR ROC curve*:ab,ti OR AUC:ab,ti OR diagnostic performance:ab,ti OR diagnosis:ab,ti OR diagnos*:ab,ti OR false positive*:ab,ti OR false negative*:ab,ti) )
AND
( ('diagnostic accuracy study'/exp OR 'cross-sectional study'/exp OR diagnostic accuracy study*:ab,ti OR test performance study*:ab,ti OR validation study*:ab,ti OR screening test*:ab,ti OR diagnosis study*:ab,ti OR sensitivity specificity study*:ab,ti) )

Cochrane Library: (Often the most straightforward, using MeSH and Text Word [tw])

("Malaria"[MeSH] OR malaria:ti,ab OR Plasmodium:ti,ab)
AND
("Rapid Diagnostic Test"[MeSH] OR "Point-of-Care Systems"[MeSH] OR rapid diagnostic test*:ti,ab OR RDT*:ti,ab OR point of care test*:ti,ab OR POCT:ti,ab OR lateral flow:ti,ab OR immunochromatographic:ti,ab OR antigen test*:ti,ab OR antibody test*:ti,ab OR near patient test*:ti,ab OR bedside test*:ti,ab OR dipstick:ti,ab OR strip test*:ti,ab OR quick test*:ti,ab)
AND
("Diagnostic Accuracy"[MeSH] OR "Sensitivity and Specificity"[MeSH] OR "Predictive Value of Tests"[MeSH] OR accuracy:ti,ab OR accurate:ti,ab OR sensitivity:ti,ab OR specificity:ti,ab OR predictive value*:ti,ab OR likelihood ratio*:ti,ab OR ROC curve*:ti,ab OR AUC:ti,ab OR diagnostic performance:ti,ab OR diagnosis:ti,ab OR diagnos*:ti,ab OR false positive*:ti,ab OR false negative*:ti,ab)
AND
("Diagnostic Test Accuracy Study"[pt] OR "Cross-Sectional Studies"[MeSH] OR diagnostic accuracy study*:ti,ab OR test performance study*:ti,ab OR validation study*:ti,ab OR screening test*:ti,ab OR diagnosis study*:ti,ab OR sensitivity specificity study*:ti,ab)

Important Considerations for Your Search:

• Iterative Process: Your first search will likely return too many or too few results. Be prepared to refine your terms. Add more synonyms, remove overly broad terms, or adjust [tiab] to specific fields if necessary.


• Language Restrictions: Decide if you will include only English-language studies or others. Add a language filter in the database if needed.


• Date Limits: Consider if you want to limit by publication date (e.g., last 10 years for newer RDTs, or no limit for comprehensive historical data).


• Grey Literature: Don't forget to search for grey literature (e.g., conference abstracts, technical reports) which may not be indexed in these databases. Websites of organizations like WHO, CDC, or manufacturers might be relevant.


• Clinical Trials Registries: Search clinical trial registries (e.g., ClinicalTrials.gov, WHO ICTRP) for ongoing or unpublished studies.


• De-duplication: Once you run searches in multiple databases and export the results to a reference manager (like EndNote, Zotero, Rayyan), you'll need to remove duplicate entries.


• Consult a Librarian: A health sciences librarian is an invaluable resource for refining search strategies and identifying additional databases or search techniques.