Pneumonia is one of the important causes of morbidity and mortality in
under-five children [1]. Vasopressin is derived from a larger precursor
peptide (pre-provasopressin), and is released together with copeptin in
equimolar ratio to vasopressin mirroring its levels, and is more stable
to measure in the circulation [2]. An increment in copeptin level with
the severity of sepsis, and it being an independent predictor of
mortality in pneumonia has been reported in adults [3,4]. This study
aimed to assess the diagnostic and prognostic significance of copeptin
levels in pediatric pneumonia.
This case-control study was conducted at
Faculty of Medicine, Cairo University, Egypt, from January 2013 to
December 2013. It included 41 children (2 months to 12 years) with a
diagnosis of community-acquired pneumonia (WHO definition of pneumonia
and having X-ray findings), or ventilator-associated pneumonia
(pneumonia occurring more than 48 hours after patients have been
intubated and received mechanical ventilation with Clinical Pulmonary
Infections Score (CPIS) [5] above six). Patients who had been
hospitalized and treated with antibiotics for
³48 hours, and those having
dehydration, immunodeficiency or malignancy, were excluded. Forty
healthy matched children were included as controls. Serum copeptin was
assayed by a commercial ELISA kit (sensitivity 1.0 pg/mL). A written
informed consent was obtained from parents before enrolment. Statistical
analysis was performed using Minitab 17. Receiver operating
characteristic (ROC) curve was plotted to estimate predictive capability
of copeptin for disease. P value <0.05 was considered
statistically significant.
The study included 29 children with community
acquired pneumonia (CAP) and 12 children with ventilator-associated
pneumonia (VAP). Thirteen children with pneumonia died. Median copeptin
levels were significantly higher in patients compared to controls (31.2
vs. 25.3 pg/mL; P=0.03). Median copeptin levels were
significantly higher in children who died as compared to survivors (89.5
vs. 28.1 pg/mL; P=0.04). There were no significant
differences in median copeptin levels between CAP and VAP patients (31.2
vs. 30.6 pg/mL; P=0.81). On logistic regression analysis,
mechanical ventilation was the only independent variable associated with
high odds of mortality (OR 10.0; 95% CI 2.1, 47.0). High (>56 pg/mL)
copeptin level was not an independent predictor of mortality (OR 2.4;
95% CI 0.6, 9.4). ROC curve (Fig. 1) showed area under
curve (AUC) of 0.62, with copeptin cut-off point of 56 pg/mL having
sensitivity and specificity of 39% and 85%, respectively, for diagnosis
of pneumonia.
|
Fig. 1 Receiver operating
characteristics (ROC) of serum copeptin levels for diagnosis of
pneumonia.
|
The present study detected elevated copeptin in
children with pneumonia, with significantly higher levels in
non-survivors compared to survivors. However, high copeptin level was
not an independent predictor for mortality. Copeptin showed low
sensitivity but high specificity for diagnosis of pneumonia.
Our findings are comparable to previously published
literature reporting serum concentrations of copeptin to be
significantly higher in patients with CAP or VAP, and their
complications [6-9]. The limitations of present study are small sample
size and lack of work-up for viral and bacterial pneumonias. We conclude
that circulating levels of copeptin are significantly increased in
children with pneumonia, and are higher in children dying of the
disease. Copeptin levels might predict unfavourable outcome in pediatric
pneumonia.
Contributors: All authors have
contributed, designed and approved the study.
Funding: None; Competing interest: None
stated.
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