C-Reactive Protein-to-Albumin Ratio (CAR) and C-Reactive Protein-to-Lymphocyte Ratio (CLR) are Valuable Inflammatory Biomarker Combination for the Accurate Prediction of Periprosthetic Joint Infection

Figures & data

Table 1 Basic Characteristics of All Patents in the PJI and AF Groups

	PJI^a (n=87)	AF^b (n=157)	P value
Age (y)	64.74±9.91	65.35±9.67	0.655
BMI^c (kg/m^2)	26.04±4.02	24.79±3.47	0.005
Gender			0.925
Male (%)	46 (52.9)	84 (53.5)
Female (%)	41 (47.1)	73 (46.5)
Joint			<0.001
Knee (%)	47 (54.0)	31 (19.7)
Hip (%)	40 (46.0)	126 (80.3)

Notes: a, PJI, periprosthetic joint infection; b, AF, aseptic failure; c, BMI, body mass index.

Table 2 Comparison of the Levels of All Inflammatory Biomarker Combination

	PJI (n=87)	AF (n=157)	P value
NLR^a	3.36±2.93	2.07±1.87	<0.001
PLR^b	160.52±112.59	135.64±82.63	<0.001
CAR^c	1.20±1.54	0.09±0.14	<0.001
CLR^d	30.34±46.28	2.25±5.17	<0.001
NAR^e	0.14±0.11	0.09±0.03	<0.001
PAR^f	8.21±3.04	5.80±1.70	<0.001

Notes: a, neutrophil-to-lymphocyte ratio; b, platelet-to-lymphocyte ratio; c, C-reactive protein-to-albumin ratio; d, C-reactive protein-to-lymphocyte ratio; e, neutrophil-to-albumin ratio; f, platelet-to-albumin ratio.

Table 3 Diagnostic Value of CRP, ESR, NLR, PLR, CAR, CLR, NAR and PAR

	AUC	95% CI	Youden Index	Optimal Cutoff Value	Sensitivity (%)	Specificity (%)	PPV^a (%)	NPV^b (%)
CRP^c (mg/L)	0.941	(0.909,0.973)	0.714	8.39	86.0	91.4	83.33	92.00
ESR^d (mm/h)	0.916	(0.881,0.951)	0.703	26.50	80.2	90.1	82.14	88.16
NLR	0.694	(0.621,0.767)	0.348	2.18	59.3	75.5	57.14	77.12
PLR	0.535	(0.453,0.617)	0.173	183.70	30.2	87.1	56.52	69.19
CAR	0.931	(0.894,0.969)	0.754	0.28	80.2	95.2	88.61	89.70
CLR	0.935	(0.901,0.967)	0.765	5.46	86.0	90.5	83.33	92.21
NAR	0.739	(0.672,0.805)	0.392	0.10	65.1	74.1	56.67	76.62
PAR	0.785	(0.725,0.845)	0.483	6.63	72.1	76.0	62.38	83.22

Notes: a, PPV, positive predictive value; b, NPV, negative predictive value; c, CRP, C-reactive protein; d, ESR, erythrocyte sedimentation rate.

Figure 1 Comparison of combined inflammatory biomarkers levels between the PJI group and the AF group. (A) neutrophil-to-lymphocyte ratio (NLR); (B) platelet-to-lymphocyte ratio (PLR); (C) C-reactive protein-to-albumin ratio (CAR); (D) C-reactive protein-to-lymphocyte ratio (CLR); (E) neutrophil-to-albumin ratio (NAR); (F) platelet-to-albumin ratio (PAR). ***P<0.001.

Figure 2 The ROC curves of CRP, ESR, NLR, PLR, CAR, CLR, NAR and PAR.

Table 4 Comparison of All Inflammatory Biomarker Combination in the Different PJI Subgroups

	Culture-Positive PJI (n=60)	Culture-Negative PJI (n=27)	P value	Acute PJI (n=11)	Chronic PJI (n=76)	P value	Knee PJI (n=47)	Hip PJI (n=40)	P value
NLR	3.53±3.29	3.00±1.93	0.783	2.79±1.71	3.45±3.07	0.711	3.30±3.07	3.44±2.80	0.753
PLR	157.06±108.18	168.22±123.62	0.790	156.29±117.52	161.13±112.65	0.646	167.33±106.31	152.51±120.42	0.233
CAR	1.34±1.67	0.88±1.17	0.183	1.15±1.48	1.20±1.55	0.868	1.02±1.36	1.40±1.72	0.362
CLR	33.90±51.45	22.14±31.37	0.102	30.36±43.79	30.33±46.91	0.789	28.37±48.16	32.65±44.18	0.721
NAR	0.14±0.13	0.12±0.06	0.759	0.11±0.05	0.14±0.12	0.332	0.12±0.07	0.15±0.15	0.285
PAR	8.06±3.18	8.55±2.71	0.190	8.20±2.95	8.21±3.07	0.959	7.35±1.97	9.22±3.72	0.009

Table 5 Combinational Diagnostic Value of the CAR and CLR Combined with CRP and ESR for PJI

	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
CAR combined with CRP and ESR
CAR or CRP	86.2	90.4	83.3	92.2
CAR and CRP	80.5	94.3	88.6	89.7
CAR or ESR	92.0	87.3	80.0	95.1
CAR and ESR	67.8	97.5	93.7	84.5
CLR combined with CRP and ESR
CLR or CRP	87.4	87.9	80.0	92.6
CLR and CRP	85.1	93.0	87.1	91.8
CLR or ESR	93.1	84.7	77.1	95.7
CLR and ESR	72.4	96.2	91.3	86.3

Table 6 Culture Results of Patients in the PJI Group

Culture Results	No. of Patients
Staphylococcus epidermidis	19
Staphylococcus aureus	11
Pseudomonas aeruginosa	3
Methicillin-resistant Staphylococcus aureus	3
Escherichia coli	3
Streptococcus pyogenes	2
Aeromonas hydrophila	1
Staphylococcus xylosus	1
Coagulase-negative Staphylococcus	1
Staphylococcus haemolyticus	1
Corynebacterium pseudodiphtheriticum	1
Staphylococcus warneri	1
Streptococcus lactis subsp. Equina	1
Dermacoccus nishinomiyaensis	1
Acinetobacter baumannii	1
Corynebacterium	1
Staphylococcus intermedia	1
Enterococcus faecalis	1
Nontuberculosis mycobacteria	1
Streptococcus agalactis	1
Streptococcus intermedius	1
Salmonella enterica subsp. Arizona	1
Corynebacterium striatum	1
Candida glabrata	1
Enterobacter cloacae	1
Pseudointermediate Staphylococcus	1
Candida parapsilosis	1
Negative	27