BioMed Central, Systematic Reviews, 1(3), 2014
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Background: Major depressive disorder (MDD) may be present in 10%–20% of patients in medical settings. Routinedepression screening is sometimes recommended to improve depression management. However, studies of thediagnostic accuracy of depression screening tools have typically used data-driven, exploratory methods to selectoptimal cutoffs. Often, these studies report results from a small range of cutoff points around whatever cutoff score ismost accurate in that given study. When published data are combined in meta-analyses, estimates of accuracy fordifferent cutoff points may be based on data from different studies, rather than data from all studies for each possiblecutoff point. As a result, traditional meta-analyses may generate exaggerated estimates of accuracy. Individual patientdata (IPD) meta-analyses can address this problem by synthesizing data from all studies for each cutoff score to obtaindiagnostic accuracy estimates. The nine-item Patient Health Questionnaire-9 (PHQ-9) and the shorter PHQ-2 and PHQ-8are commonly recommended for depression screening. Thus, the primary objectives of our IPD meta-analyses are todetermine the diagnostic accuracy of the PHQ-9, PHQ-8, and PHQ-2 to detect MDD among adults across all potentiallyrelevant cutoff scores. Secondary analyses involve assessing accuracy accounting for patient factors that may influenceaccuracy (age, sex, medical comorbidity).Methods/design: Data sources will include MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, PsycINFO, andWeb of Science. We will include studies that included a Diagnostic and Statistical Manual or International Classificationof Diseases diagnosis of MDD based on a validated structured or semi-structured clinical interview administered within2 weeks of the administration of the PHQ. Two reviewers will independently screen titles and abstracts, perform full articlereview, and extract study data. Disagreements will be resolved by consensus. Risk of bias will be assessed with the QualityAssessment of Diagnostic Accuracy Studies-2 tool. Bivariate random-effects meta-analysis will be conducted for the fullrange of plausible cutoff values. Discussion: The proposed IPD meta-analyses will allow us to obtain estimates of the diagnostic accuracy of the PHQ-9,PHQ-8, and PHQ-2.