Article

Diagnostic value of neutrophil CD64 combined with CRP for neonatal sepsis: A meta-analysis

a b s t r a c t

Background: Sepsis is the leading cause of morbidity and mortality in newborns. CD64 combined with c-reactive protein (CRP) could improve the sensitivity and specificity of neonatal sepsis diagnosis, but the results were still controversial. Therefore, this meta-analysis was conducted to clarify the importance of CD64 combined with CRP in the diagnosis of neonatal sepsis.

Methods: The researches published as of December 24, 2018 were comprehensively searched in PubMed, Embase (included Embase and Medline), the Cochrane Library and Web of Science. Totally, 8 articles were included, in- volving 1114 objects. Statistical calculations were performed using Stata14.0 and Review Manager 5.3.

Results: The diagnostic accuracy of all included studies was pooled as follows: sensitivity, 0.95 (95% CI: 0.86-0.98); specificity, 0.86 (95% CI: 0.74-0.93); positive likelihood ratio (PLR), 6.8 (95% CI: 3.50-13.20); nega- tive likelihood ratio (NLR), 0.06 (95% CI: 0.02-0.18); Diagnostic odds ratio (DOR), 118.0 (95% CI: 25.00-549.00), and the area under the curve (AUC) was 0.96 (95% CI: 0.94-0.97). It was found that heterogeneity was not caused by threshold effect (P = 0.16), but the results of sensitivity (I2 = 87.57%) and specificity (I2 = 89.07%) analyses indicated significant heterogeneity between studies.

Conclusions: The combined application of CD64 and CRP improved the accuracy of neonatal sepsis diagnosis.

(C) 2019

  1. Introduction

World Health Organization (WHO) estimates for 195 countries indi- cate that neonatal bacterial infections cause about 680,000 neonatal deaths each year, or about a quarter of all neonatal deaths [1,2], and sep- sis is the leading cause of morbidity and mortality in newborns [3-5]. In routine clinical practice, it is difficult to diagnose neonatal sepsis rapidly and accurately due to various reasons. Therefore, the accuracy of diag- nostic tests should be improved [6]. At present, commonly used domes- tic Infection detection indicators included blood routine c-reactive protein (CRP), procalcitonin , blood culture, etc., but these tradi- tional detection indicators generally have problems such as low sensi- tivity and low specificity and long detection cycle time.

The traditional gold standard for the diagnosis of sepsis is blood cul- ture, but the test needs at least 2 days to get the result [7,8]. CRP began to increase 24-48 h after bacterial infection [9,10], that it is a late indica- tor of infection. However, some studies have shown that CRP increases physiologically three days after birth, which is prone to misdiagnosis [11]. Other diagnostic methods such as PCT also have some limitations [12]. As a novel cytokine in recent years, CD64 has significant value in

* Corresponding author at: Department of Pediatrics, Fuling Central Hospital of Chongqing City, No. 2 Gaosuntang Road, Fuling District, Chongqing 408000, China.

E-mail address: [email protected] (X. Jiang).

the diagnosis of bacterial infection and sepsis [13,14]. Dai et al. and Shi et al. revealed that the detection of neutrophil CD64 alone had some problems such as low sensitivity and specificity [15,16]. Thus, it is better to combine with another serum biomarker. Literature review showed that CD64 combined with CRP could improve the sensitivity and speci- ficity of neonatal sepsis diagnosis, but the results were still controver- sial. Therefore, this meta-analysis was conducted to clarify the importance of CD64 combined with CRP in the diagnosis of neonatal sepsis.

  1. Methods
    1. Search strategies

We systematically searched (updated to December 24, 2018) PubMed, Embase (included Embase and Medline), the Cochrane Library, and Web of Science for studies that assessed the accuracy of neutrophil CD64 combined CRP for the diagnosis of neonatal sepsis, used the fol- lowing key words and Mesh terms, such as (“sepsis” or “septicemia” or “septicaemia” or “infection”) and (“CD64” or “neutrophil CD64, nCD64” or “nCD64”) and (“neonatal” or “newborn”). We further manu- ally searched the included references to avoid missing articles that might be included.

https://doi.org/10.1016/j.ajem.2019.05.001 0735-6757/(C) 2019

Fig. 1. Flow diagram of study Selection process.

Selection criteria

If the following inclusion criteria were met, relevant studies were in- cluded: 1) To investigate the diagnostic value of nCD64 combined with CRP in neonatal sepsis; 2) providing the golden standard of blood cul- ture; 3) the number of true positive (TP), false positive (FP), true nega- tive (TN) and false negative (FN) can be obtained by calculation. The exclusion criteria in this study were as follows: 1) Eliminated the con- ference abstract or report, review or meta-analysis, and republished ar- ticles; 2) studies with insufficient data to extract were also excluded.

Data extraction and quality assessment

Two independent authors performed the initial search, imported EndNote and deleted the duplicate record automatically or manually, screened the titles and abstract, recognized the potentially studies,

and got the full text. The two authors independently determined the in- cluded references and extracted the data, and the differences were re- solved by a third author. The following data were extracted from each study: surname of the first author, Publication year, country, number of infected and non-infected groups, the type of sepsis, nCD64 analysis method, analysis cutoff, sensitivity, specificity, TP, FP, FN, TN. The quality assessment of diagnostic research methodologies was conducted in ac- cordance with QUADAS-2 tool guidelines [17].

Statistical analysis

STATA 14.0 and Review Manager 5.3 were used to perform the meta-analysis. In the diagnostic meta-analysis, considering that the combined CD64 test and the single CD64 test may have different diag- nostic effects on neonatal sepsis, and the single test has been studied [15,16], we collected the individual data of CD64 combined CRP

Table 1

Characteristics of the included studies.

Author

Year

Country

Infected/noninfected

Diagnosis standard

Type of sepsis

Infants

ncd64 analysis

Analysis cutoff

Sensitivity (%)

Specificity (%)

TP

FP

FN

TN

Qin

2017

China

37/21

Clinical or

c

N

FCM

2.58 CD64 index

97.29

76.19

31

4

6

17

Shimi

2016

Egypt

60/60

proven

Clinical or

c

Preterm +

FCM

91.1 CD64 index

100

100

60

0

0

60

Yang

2015

China

60/60

proven

Clinical or

b

term

Preterm +

FCM

2.5 CD64 index

88.64

87.8

53

7

7

53

proven

term

Du

2014

China

88/70

Clinical

a

Preterm

FCM

1010 PE-molecules

77.27

90

68

7

20

63

Genel

2012

Turkey

49/35

Clinical or

c

Preterm +

FCM

bound/cell

3.05 MFI

89

71

44

10

5

25

Dilli

2010

USA

35/74

proven

Clinical or

c

term

Preterm +

FCM

4.93 CD64 index

97.1

68.9

34

23

1

51

Ng

2004

China

115/223

proven

Clinical or

a

term

Term

FCM

6136 PE molecules

97

71

112

65

3

158

proven

bound/cell

Ng

2002

China

37/90

Proven

b

Preterm

FCM

4000 PE-molecules bound/cell

100

90

37

9

0

91

NOTE: a, early-onset; b, late-onset; c, early and late-onset; FCM, flow cytometric technology; MFI, mean fluorescence intensity; TP, true positive; FP, false positive; TN, true negative; FN, false negative.

Fig. 2. Quality assessment of diagnostic accuracy for the included studies.

diagnostic markers from the included studies. Therefore, we calculated the pooled sensitivity, specificity, PLR, NLR, DOR and 95% CI of CD64 combined CRP diagnosis using a bivariable meta-analysis model [18]. We constructed the symmetric receiver operator characteristic curve (SROC), calculated the area under the SROC curve, and evaluated the overall performance of CD64 combined with CRP in the diagnosis of neonatal sepsis. spearman correlation coefficient was used to test the inter-study heterogeneity caused by threshold effect [19]. The Cochran Q test and I2 statistics have always been used to evaluate non- threshold effects [20]. Fagan’s nomogram was used to investigate the clinical value of CD64 combined with CRP in the detection of neonatal sepsis. The Deek’s funnel plot method was used to explore publication bias (P b 0.05) [21]. The sensitivity analysis was performed by excluding one study at a time and recalculating the risk effect.

  1. Results

A total of 293 studies were found through literature search, of which 127 studies were excluded due to duplicates and 134 studies were ex- cluded after we reviewed the retrieved literature’s titles and abstracts. After reading the full-text of the remaining 32 studies, we further elim- inated 24 studies, of which 23 were identified as CD64 alone and one as non-CD64 combined with CRP. Finally, 8 studies were included in this

meta-analysis [22-29]. The flow chart of the meta-analysis is repre- sented in Fig. 1. The basic information and quality evaluation results in- cluded in the study are shown in Table 1 and Fig. 2.

Diagnostic accuracy of CD64 + CRP for neonatal sepsis

The pooled results for diagnostic accuracy of all included studies were as follows: sensitivity, 0.95 (95% CI: 0.86-0.98); specificity, 0.86

(95% CI: 0.74-0.93); PLR, 6.8 (95% CI: 3.50-13.20); NLR, 0.06 (95% CI:

0.02-0.18); and DOR, 118.0 (95% CI: 25.00-549.00), and the AUC was

0.96, (95% CI: 0.94-0.97) (Figs. 3 and 4).

Nomogram of Fagan was regarded as a graphical tool for digging out the clinical diagnostic values of CD64 + CRP in neonatal sepsis detec- tion. When 20% value was selected as the pre-test probability, the pos- itive results of CD64 + CRP showed the post-test probability of correctly diagnosing neonatal sepsis would rise to 63%, while negative results of CD64 + CRP indicated the post-test probability would drop to 1%, as demonstrated in the Fagan plot in Fig. 5.

Heterogeneity and publication bias

It was found that heterogeneity was not caused by threshold effect (P = 0.16), but the results of sensitivity (I2 = 87.57%) and specificity

Fig. 3. Sensitivity and specificity forest of CD64 combined with CRP in the diagnosis of neonatal sepsis.

Fig. 4. SROC curves of CD64 combined with CRP in the diagnosis of neonatal sepsis.

(I2 = 89.07%) analysis indicated significant heterogeneity between studies (Fig. 3). In addition, Deeks’ funnel plot showed no significant publication bias in our study (P = 0.960) (Fig. 6).

Fig. 5. Nomogram of Fagan describes the probability CD64 combined with CRP to confirm or exclude neonatal sepsis patients.

Fig. 6. funnel plots for the assessment of potential diagnosis bias in CD64 combined with CRP assays.

Sensitivity analysis

An outlier study was found through the sensitivity analysis and out- lier detection (Fig. 7A, B). After the abnormal study was excluded, the combined results were sensitivity 0.92 (95% CI: 0.85-0.96), specificity

0.82 (95% CI: 0.74-0.88), PLR 5.20 (95% CI: 3.50-7.60), NLR 0.09 (95%

CI: 0.05-0.18), DOR 56.00 (95% CI: 27.00-115.00), AUC 0.93 (95% CI:

0.91-0.95), however, the results were a change from previous results. Further analysis found that there was still outlier in the study, and the combined results after elimination had minimal changes: sensitivity

0.91 (95% CI: 0.83-0.95), specificity 0.80 (95% CI: 0.72-0.86), PLR 4.60

(95% CI: 3.30-6.40), NLR 0.11 (95% CI: 0.06-0.20), DOR 41.00 (95% CI:

24.00-71.00), AUC 0.91 (95% CI: 0.89-0.94). The heterogeneity was re- duced after removing the literature one by one (sensitivity I2 = 81.95%, specificity I2 = 81.21%; sensitivity I2 = 79.35%, specificity I2 = 72.94%).

  1. Discussion

Neonatal sepsis is one of the important causes of high neonatal mor- tality. Therefore, accurate diagnosis and appropriate medicine are par- ticularly important for improving adverse outcomes. However, numerous studies have shown that clinical signals, non-specificity, and laboratory tests, including blood cultures, are not always reliable [30]. Up to now, many markers for the diagnosis of neonatal sepsis have been proposed, such as c-reactive protein, PCT, IL-6, etc. However, the identification of NS by a single biomarker is not reliable enough at present. More researchers focused on the combination of different bio- markers in different clinical environments, hoping to obtain clearer con- clusions [31,32]. Thus, we conducted this meta-analysis to investigate the important role of CD64 combined with CRP in the diagnosis of neo- natal sepsis. The main finding of this meta-analysis was that CD64 com- bined with CRP could improve the accuracy of neonatal sepsis diagnosis. A meta-analysis of the diagnostic value of ncd64 in the independent di- agnosis of neonatal sepsis was performed in the two studies, and a large difference was found between the results of the two studies, which may be caused by the different inclusion and exclusion criteria of the two stud- ies. The integrated sensitivity, specificity, PLR, NLR, DOR and AUC of Dai’s and Shi’s studies were 80% (95% CI: 69-88%), 83% (95% CI: 71-90%), 4.6

(95% CI: 2.5-8.6), 0.24 (95% CI: 0.14-0.41), 19 (95% CI: 6-57), 0.88 (95%

CI: 0.85-0.91); 0.77 (95% CI: 0.74-0.79), 0.74 (95% CI: 0.72-0.75), 3.58

(95% CI: 2.85-4.49), 0.29 (95% CI: 0.22-0.37), 15.18 (95% CI:

9.75-23.62), respectively [15,16]. Our study found that the value of CD64 combined with CRP in the diagnosis of neonatal sepsis was superior

Fig. 7. Influence analysis and outlier detection. A and B, (a) goodness of fit, (b) bivariate normality, (c) influence analysis, and (d) outlier detection.

to the independent diagnosis of CD64. In addition, it was found that CD64

+ CRP had higher diagnostic value by comparing other Diagnostic markers such as IL-6, PCT, CRP, PCT + CRP in the meta-analysis [33-36].

However, there was significant statistical heterogeneity in some analyses that required further explanation. Threshold effect, publication bias, sensitivity analysis and other methods were used to identify the sources of heterogeneity. First, the analysis results showed that the Spearman correlation coefficient and P value between the 8 studies were 0.40 and 0.16, indicating that the heterogeneity was not caused by threshold effect. Second, Deek’s funnel plot asymmetry test showed no publication bias (P = 0.96). Third, sensitivity analysis found that het- erogeneity decreased after the exclusion of abnormal studies, which may be one of the reasons for the high heterogeneity in this study. In ad- dition to the above reasons, we carefully read the content of the article and found that the cutoff values included in the study were all different, which may be one of the reasons for the high heterogeneity. Further- more, the type of sepsis (early-onset, late-onset, or early and late- onset) and the type of patients (preterm, term, or preterm + term) in- cluded in the study may be the cause of heterogeneity.

There were also several limitations to this meta-analysis. First, as the number of the included literatures was b10, meta-regression quantita- tive analysis of heterogeneous sources was not conducted. Second, the sensitivity analysis results showed change as a result and poor stability after eliminating outlier literature, although the merged results (such as sensitivity, specificity, and AUC) still had relatively high diagnostic value of CD64, high-quality diagnostic experiments are still needed to further validate the important role of CD64 combined with CRP in the diagnosis of neonatal sepsis.

In conclusion, the combination of CD64 and CRP improves the accu- racy of the diagnosis of neonatal sepsis. However, further studies are re- quired to confirm these findings.

Conflict of interests

All authors declare that they have no conflict of interests.

Acknowledgments

None.

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