False-negative RT-PCR in SARS-CoV-2 disease: experience from an Italian COVID-19 unit

Marcello Di Paolo; Alessandra Iacovelli; Federica Olmati; Ilaria Menichini; Alessandra Oliva; Martina Carnevalini; Elda Graziani; Claudio Maria Mastroianni; Paolo Palange

doi:10.1183/23120541.00324-2020

Tables

TABLE 1

Patients’ characteristics

Age years	59.5 (30–86)
Males/females n	11/5
Comorbidities
Arterial hypertension	11 (68.7%)
Type 2 diabetes mellitus	5 (31.2%)
Malignancies	2 (12.5%)
Pre-existing respiratory diseases	3 (18.7%)
Other	6 (37.5%)
Data at hospital admission
Time between symptoms onset and admission days	5 (0–15)
Reported symptoms
Fever ≥38.0°C	14 (87.5%)
Dyspnoea	14 (87.5%)
Cough	7 (43.7%)
Gastrointestinal symptoms	2 (12.5%)
Other	3 (18.7%)
Body temperature °C	37.5 (37.2–38.9)
Blood gas analysis^#
P_a_O₂ mmHg	69 (48–98)
P_a_CO₂ mmHg	31 (27–38)
pH	7.46 (7.39–7.52)
P_aO₂/F_IO₂ mmHg	329 (228–467)
Laboratory findings
Haemoglobin g·dL⁻¹	13.8 (9.2–15.0)
Red blood cells ×10¹² per L	4.7 (3–0–5.4)
White blood cells ×10⁹ per L	8.6 (3.8–20.6)
Neutrophils ×10⁹ per L	7.2 (3.9–18.9)
Lymphocytes ×10⁹ per L	0.8 (0.4–2.0)
Monocytes ×10⁹ per L	0.4 (0.1–3.0)
Platelets ×10⁹ per L	231.0 (102.0–561.0)
C-reactive protein g·dL⁻¹	13.6 (1.1–37.5)
Ferritin µg·L⁻¹	371 (80–1364)
D-dimer µg·L⁻¹	1256 (197–4473)
Respiratory support
Oxygen	12 (75.0%)
Positive end-expiratory pressure	7 (43.7%)
High-flow nasal cannula	1 (6.2%)
Noninvasive ventilation	0 (0%)
Orotracheal intubation	0 (0%)
Length of hospitalisation days	25 (8–49)
Outcome
Discharge home	14 (87.5%)
Intensive care unit	0 (0%)
Death	2 (12.5%)
RT-PCR assays
Nasopharyngeal swabs	66 (89.2%)
BALF	6 (8.1%)
Rectal swabs	2 (2.7%)
RT-PCR repetitions during hospital stay/time from symptom onset days
3	16 (100%)/8 (2–20)
4	13 (81.2%)/18 (9–27)
5	9 (56.2%)/21 (10–27)
6	4 (25.0%)/24 (17–24)
RT-PCR positive results^¶
Patients	3 (18.7%)
Testing	3 (4.1%)
Anti-SARS-CoV-2 serum antibodies⁺
IgM	8 (88.9%)
IgG	9 (100%)
Time from symptom onset days	25 (20–35)

Data are presented as median (range) or n (%), unless otherwise stated. F_IO₂: inspiratory oxygen fraction; P_a_O₂: arterial oxygen tension; P_a_CO₂: arterial carbon dioxide tension; BALF: bronchoalveolar lavage fluid. ^#: F_IO₂ 0.21; ^¶: after two first negative results; ⁺: N=9.