Validation of lung ultrasound, performed by family physicians, as an initial imaging test to diagnose pneumonia in COVID-19 patients.

Mª Cristina Gadea-Ruiz, Oana Bulilete, Magdalena Esteva-Cantó, José Ignacio Ramírez-Manent, Bernardino Oliva-Fanlo

Keywords: ultrasound, pneumonia, COVID-19, primary care

Background:

Most studies on lung ultrasound and COVID-19 pneumonia have been conducted in patients in hospital environments. Few studies assess the diagnosis accuracy of point-of-care ultrasound (POCUS) in COVID-19 patients with suspected pneumonia visited in primary care. The only prospective study on diagnostic value of POCUS for the diagnosis of COVID-19 pneumonia found a sensitivity (S) of 87.8% and a specificity (SP) of 58.5%.

Research questions:

Which is the value of POCUS for the diagnosis of pneumonia in patients with SARS-CoV-2 virus infection, performed by family physicians in primary care health centers and at the patients' homes?

Method:

Prospective observational study of diagnostic validation.
Setting: Patients attended in primary care (health center or at home), aged ≥ 18 years diagnosed with COVID-19 by PCR were included.
Variables: sociodemographics, vital signs (temperature, pulse oximetry, respiratory and heart rate), comorbidities, LUS results.
Gold standard: final diagnosis of pneumonia by hospital clinical records review.
Analyses: descriptive, bivariate (positive vs. negative LUS), sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV).
Project approved by the Ethics Committee and all participants signed informed consent before inclusion.

Results:

383 patients.
Overall LUS values: sensitivity 68.3% (95%CI 62.5%-73.6%), specificity 43.6% (95%CI 33.5-54.2%), PPV 78.7% (95%CI 73.0-83.5%), NPV 31.1% (95%CI 23.5-39.8%).
According to ultrasound finding:
- Pleural B-lines/irregularities S:64.9% (95%CI 58.8-70.6%), E:50.0% (95%CI 38.8-61.2%)
- subpleural condensation S:50.8% (95%CI 43.4-58.2%); E:61.2% (95%CI 48.5-72.6%)
- lobar consolidation S:9.0% (95%CI 4.5-16.8%), E:89.1% (95%CI 75.6-95.9%).

Conclusions:

POCUS sensitivity for the diagnosis of pneumonia in COVID-19 patients is comparable to the one achieved by the chest X-ray in COVID-19 and non-COVID-19 patients (using CT scan as gold standard).
In patients with clinical suspicion of COVID pneumonia, POCUS performed by family physicians could be a helpful tool to support diagnosis at primary care.

Points for discussion:

Integration of POCUS in GPs workflow

training and competency requirements for physicians

changes in resource allocation within the healthcare system and shifts in the role of primary care physicians

#52