A systematic review and metanalysis of diagnostic yield of BAL for detection of SARS-CoV-2

BACKGROUND: The gold standard for diagnosing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is microbiological confirmation by reverse transcriptase-polymerase chain reaction (RT-PCR)(1) most commonly done using oropharyngeal (OP) and nasopharyngeal swabs (NP). But in suspected cases, where these samples are false-negative, bronchoalveolar lavage (BAL) may prove diagnostic. OBJECTIVES: Hence, the diagnostic yield of BAL for detection of SARS-CoV-2 in cases of non-diagnostic upper respiratory tract samples is reviewed. METHODS: Databases such as MEDLINE, Scopus, and Google Scholar were searched using a systematic search strategy. The current study has been in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and has been registered with the International Prospective Registry of Systematic Reviews (CRD42020224088). RESULTS: 911 records were identified at initial database extraction, of which 317 duplicates were removed and, 596 records were screened for inclusion eligibility. We included total 19 studies in the systematic review, and 17 were included in metanalysis. The pooled estimate of SARS-CoV-2 positivity in BAL was 11% (95%CI: 0.01–0.24). A sensitivity analysis also showed that the results appear to be robust and minimal risk of bias amongst the studies. CONCLUSION: The current study demonstrates that BAL can be used to diagnose additional cases primary disease and superadded infections in patients with severe COVID-19 lower respiratory tract infection.