A systematic review and metanalysis of diagnostic yield of BAL for detection of SARS-CoV-2.
Sumita Agrawal, Akhil Dhanesh Goel, Nitesh Gupta and 2 others
PMID 34929538WHAT IT FOUND
Among patients with negative nose or throat swabs, bronchoalveolar lavage found SARS-CoV-2 in 11% of specimens across 17 studies.
The estimate was very uncertain because studies varied widely, so it may not apply to every patient.
Key findings
01The pooled proportion of BAL specimens positive for SARS-CoV-2 was 11% across 17 studies included in the final meta-analysis.
02The studies varied widely, so the 11% pooled estimate may not be consistent across settings.
03Excluding any one study did not significantly change the pooled estimate.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The pooled estimate had very high heterogeneity, with I squared 96%, so the 11% yield is not stable across studies. The confidence interval is wide, from 0.01 to 0.24, so the true yield could be very low or higher than 11%. Studies with 10 or fewer BAL samples were excluded, so the review does not address very small BAL series. The authors note that the evidence was changing and may need revision. The pooled result is a proportion of positive specimens, not a treatment effect or clinical outcome benefit.
The easy way to misread this
Do not read the 11% pooled positivity as evidence that BAL should be used routinely when nose or throat swabs are negative. The estimate is very uncertain because the studies varied widely, so it does not show that BAL will help most patients.