Salivary C-reactive protein and mean platelet volume as possible diagnostic markers for late-onset neonatal pneumonia

Table 1 Demographic and laboratory findings of neonates with late-onset pneumonia and the control group

Parameter		Neonates with LOP, n = 40	Control group, n = 40	P value
Sex	M	21	22	> 0.05
	F	19	18	> 0.05
	M:F	1.1:1	1.2:1	> 0.05
Age in d		15 ± 4.6	14 ± 5	> 0.05
Anthropometric measurements at admission	Weight in g	3454 ± 360	3728 ± 316	< 0.0001a
	Length in cm	51.42 ± 1.0	51.87 ± 0.57	< 0.05a
	Head circumference	36.21 ± 0.8	36.7 ± 0.60	< 0.05a
Type of delivery	Normal	14 (35%)	16 (40%)	> 0.05
	CS	26 (65%)	24 (60%)	> 0.05
APGAR score	At 1 min	7.1 ± 2.5	7.4 ± 2.3	> 0.05
	At 5 min	8.5 ± 3.2	9 ± 2.9	> 0.05
Maternal illness	Non	31 (77.5%)	32 (80%)	> 0.05
	DM	3 (7.5%)	2 (5%)	> 0.05
	hypertension	2 (5%)	5 (12.5%)	> 0.05
	UTI	4 (10%)	3 (7.5%)	> 0.05
Serum CRP in mg/L		38.58 ± 24.9	3.60 ± 2.25	< 0.0001a
sCRP in mg/L		6.17 ± 3.38	3.07 ± 1.24	< 0.0001a
MPV		9.99 ± 0.94	8.42 ± 0.83	< 0.0001a
Serum CRP/MPV		3.86 ± 2.29	0.42 ± 0.39	< 0.0001a

^aP < 0.05.

Data are n, n (%), or mean ± SD. SCRP: C-reactive protein; CS: Caesarean section; DM: Diabetes mellitus; F: Female; LOP: Late-onset pneumonia; M: Male; MPV: Mean platelet volume; sCRP: Salivary C-reactive protein; UTI: Urinary tract infection.

Table 2 Clinical and radiological findings of neonates with late onset pneumonia

Finding	Number of 40 total	Percentage (%)
Clinical findings
Fever	26	65.0
Cough	28	70.0
Degree of respiratory distress
1	7	17.5
2	16	40.0
3	13	32.5
4	4	10.0
Decreases air entry	33	82.5
Fine crepitations	35	87.5
Radiological findings
Homogenous ground glass shadow	4	10.0
Pneumonic patches and air bronchogram	30	75.0
Interstitial pneumonia	4	10.0
Complete white lung	1	2.5
Complications	1	2.5
Need for oxygen support
Nasal canula	31	77.5
nCPAP	5	12.5
Mechanical ventilation	4	10.0

nCPAP: Nasal continuous positive airway pressure.

Table 3 Validity (area under the curve, sensitivity, specificity) of mean platelet volume, salivary C-reactive protein, serum C-reactive protein, and serum C-reactive protein/mean platelet volume to discriminate patients from controls

Parameter	AUC	95%CI	P value	Cut-off value	Sensitivity	Specificity	PPV	NPV
MPV	0.87	0.77–0.97	< 0.001a	> 8.8	86.67	80.0	81.2	85.7
Serum CRP	0.81	0.70–0.92	< 0.001a	> 6 mg/dL	76.67	60.0	65.7	72.0
sCRP	0.80	0.68–0.92	< 0.001a	> 3.5 mg/dL	76.67	83.33	82.1	78.1

^aP < 0.05.

AUC: Area under the curve; CI: Confidence interval; CRP: C-reactive protein; MPV: Mean platelet volume; NPV: Negative predictive value; PPV: Positive predictive value; sCRP: Salivary C-reactive protein.

Table 4 Correlation of serum C-reactive protein with each salivary C-reactive protein and mean platelet volume, neonates with late-onset pneumonia (n = 40)

Parameter	r value	P value
Serum CRP vs sCRP	0.59	0.001a
Serum CRP vs MPV	0.66	< 0.001a
Salivary CRP vs MPV	0.54	0.01a

^aP < 0.05.

CRP: Salivary C-reactive protein; MPV: Mean platelet volume; sCRP: Salivary C-reactive protein.

Table 5 Diagnostic validity (area under the curve, sensitivity, specificity) for salivary C-reactive protein to predict serum C-reactive protein > 6 (n = 31) from serum C-reactive protein ≤ 6 (n = 9) in the patient group (n = 40)

Parameter	AUC	95%CI	P value	Cut-off Value	Sensitivity	Specificity	PPV	NPV
sCRP	0.89	0.77-1.1	< 0.001a	> 3.2	91.3	71.4	91.3	71.4

^aP < 0.05.

AUC: Area under the curve; CI: Confidence interval; NPV: negative predictive value; PPV: Positive predictive value; sCRP: Salivary C-reactive protein.