Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio Predict Mortality in Patients with Diabetic Foot Ulcers Undergoing Amputations

Figures & data

Table 1 Summary of Baseline Patient Characteristics

	High PLR N=200	Low PLR N=148		High NLR N=155	Low NLR N=193
Clinical Parameters	N (N% or SD)	N (N% or SD)	p-value	N (N% or SD)	N (N% or SD)	p-value
Age	67.31±9.49	65.07±9.77	0.033	68.11±9.74	64.95±0.68	0.002
Sex			0.813			0.216
Male	130(65%)	98(66.21%)		107(69.03%)	121(62.69%)
Female	70(35%)	50(33.78%)		48(30.97%)	72(37.3%)
BMI, kg/m^2	22.65±6.25	23.64±4.02	0.101	23.04±5.24	23.04±5.51	0.852
SBP (mmHg)	145.31±22.86	142.46±24.40	0.269	143.87±24.03	144.28±23.18	0.873
DBP (mmHg)	74.98±12.91	76.18±12.55	0.383	74.84±13.66	76.01±13.66	0.398
Duration of diabetes (years)	12.46±8.22	12.16±7.2	0.417	13.18±8.286	11.65±7.296	0.007
Coronary heart disease	16(8%)	9(6.08%)	0.493	12(7.74%)	13(6.73%)	0.436
Cerebral vascular disease	20(10%)	14(9.45%)	0.867	19(12.25%)	15(7.77%)	0.158
Lower extremity arterial diseases	180(90%)	130 (90.5%)	0.867	138(89.03%)	176(91.19%)	0.500
Wagner classification			0.01			0.110
2 and 3	79(39.5%)	79(53.37%)		63(40.65%)	95(49.22%)
4 and 5	121(60.5%)	69(46.63%)		92(59.35%)	98(50.78%)
Smoking history (current or ever)	67(33.5%)	52(35.1%)	0.751	54(34.83%)	65(33.68%)	0.821
Prior history of amputation	23(14.7%)	10(8.3%)	0.168	16(10.32%)	22(11.39%)	0.749
Laboratory data
HbA1c%	9.49±2.29	9.63±2.39	0.598	9.42±2.38	9.62±2.25	0.472
FBG	8.99±3.11	8.57±3.15	0.265	9.30±3.26	8.56±3.10	0.033
White blood cell	7.06±2.66	6.57±1.98	0.055	8.22±2.60	5.826±1.60	0.004
Mean platelet volume	9.83±1.02	10.53±1.09	<0.001	9.94±1.15	10.29±1.06	<0.001
Fibrinogen	7.16±1.82	6.09±1.90	<0.001	6.95±1.84	6.51±1.97	0.037
Total bilirubin	7.48±3.15	8.39±5.21	0.062	7.46±3.6	8.19±4.57	0.103
Direct bilirubin	3.45±1.94	3.81±3.28	0.195	3.55±2.79	3.64±2.43	0.738
Indirect bilirubin	4.03±1.74	4.57±2.79	0.38	3.91±1.60	4.54±2.65	0.006
Albumin	30.7±5.39	32.24±4.71	0.006	30.3±4.97	32.19±5.17	0.001
Creatinine	136.51±163.12	108.01±141.7	0.083	158.65±189.36	96.87±113.33	<0.001
Uric acid	295.03±118.54	294.11±99.2	0.939	314.65±124.56	278.50±95.23	0.003
Blood urea nitrogen	7.73±7.94	6.674±3.71	0.024	8.41±5.25	6.37±3.51	<0.001

Note: Data are presented as the means ± standard deviation (SD), the median (interquartile range) for continuous variables or the number (%) for categorical variables.

Abbreviations: BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; FBG, fasting blood glucose.

Figure 1 ROC curves for predicting the primary endpoint (all-cause mortality) for baseline NLR and PLR. The optimum cut-off values were NLR ≥ 2.76 (sensibility 69.2%, specificity 62.6%) and PLR ≥ 160.05 (sensibility 73.1%, specificity 47%).

Abbreviations: ROC, receiver operating characteristic; NLR, neutrophil-to-lymphocyte ratio; PLR, platelet-to-lymphocyte ratio.

Figure 2 Kaplan–Meier analysis showing cumulative mortality according to the optimal cut off value. (A) Platelet-to-lymphocyte ratio (160.05). (B) Neutrophil-to-lymphocyte ratio (2.76).

Abbreviation: OS, overall survival.

Table 2 Univariate and Multivariate Analyses of the Overall Survival of Patients with Diabetic Foot Ulcers Undergoing Amputations

Covariate	Univariate		Multivariate
	HR (95% CI)	p-value	HR (95% CI)	p-value
Age	1.072(1.045–1.099)	<0.001	1.074(1.045–1.104)	<0.001
Sex
Male	1		-	-
Female	0.960(0.597–1.545)	0.868	-	-
Coronary heart disease	1.360(0.653–2.830)	0.411	-
Cerebral vascular disease	0.862(0.375–1.985)	0.728	-	-
Wagner classification
2 and 3	1		-	-
4 and 5	2.366(1.443–3.878)	<0.001	2.274(1.351–3.828)	0.002
Smoking history (current or ever)	0.700(0.427–1.147)	0.157	-	-
Prior history of amputation	1.002(0.515–1.948)	0.996	-	-
Systolic blood pressure (mmHg)	1.017(1.005–1.028)	0.005	1.007(0.997–1.018)	0.149
Diastolic blood pressure (mmHg)	1.003(0.984–1.022)	0.775	-	-
PLR≥ 155.41	3.335(2.059–5.402)	<0.001	1.794(1.014–3.174)	0.045
NLR≥ 3.06	2.224(1.347–3.670)	0.002	2.029(1.177–3.499)	0.011
FBG	0.962(0.888–1.043)	0.347	-	-
Platelet	1.000(0.998–1.002)	0.840	-	-
Mean platelet volume	0.952(0.780–1.162)	0.627	-	-
Fibrinogen	1.052(0.934–1.185)	0.399	-	-
Total bilirubin	1.007(0.953–1.064)	0.797	-	-
Direct bilirubin	1.069(0.998–1.144)	0.055	1.154 (1.081–1.232)	<0.001
Indirect bilirubin	0.909(0.796–1.038)	0.159	-	-
Albumin	0.984(0.943–1.028)	0.474	-	-
Creatinine	1.002(1.002–1.003)	<0.001	1.003(1.001–1.004)	<0.001
Uric acid	1.003(1.002–1.005)	<0.001	1.001(0.999–1.003)	0.277
BUN	1.086(1.052–1.122)	<0.001	0.998(0.931–1.071)	0.964

Note: In the multivariate model, the following variables were added as independent variables: age, Wagner classification, PLR, NLR, creatinine, direct bilirubin, uric acid and blood urea nitrogen.

Abbreviations: HR, hazard ratio; CI, confidence interval; SBP, systolic blood pressure; PLR, platelet-to-lymphocyte ratio; NLR, neutrophil-to-lymphocyte ratio; BUN, blood urea nitrogen; FBG, fasting blood glucose.