Relationship of Red Cell Index with the Severity of Chronic Obstructive Pulmonary Disease

Figures & data

Figure 1 Flow chart showing the literature search and selection. Specific reasons for exclusion of studies are also shown.

Abbreviation: COPD, chronic obstructive pulmonary disease.

Table 1 Comparison of COPD Patients and Healthy Controls

	Total (n = 207)	Group A (n = 100)	Group B (n = 107)	p
Age (years)	70.14 ± 8.38	70.17 ± 8.41	70.12 ± 8.39	0.968
Gender (male, n%)	178 (85.99)	87 (87.00)	91 (85.05)	0.467
RBC (10^12/L)	4.50 ± 0.57	4.28 ± 0.44	4.70 ± 0.60	<0.001
Hb (g/L)	137.85 ± 19.0	130.19 ± 13.82	145.08 ± 20.39	<0.001
PLT (10^9/L)	219.84 ± 65.05	232.75 ± 75.34	207.66 ± 51.01	0.006
Lym (10^9/L)	2.61 ± 9.30	1.62 ± 0.73	3.54± 12.91	0.138
RCI	1.86 ± 1.12	2.10 ± 1.44	1.64 ± 0.64	0.004
NLR	2.80 ± 2.95	4.02 ± 3.80	1.65 ± 0.74	<0.001
PLR	134.29 ± 83.42	170.89 ± 101.61	99.74 ± 37.04	<0.001
RDW	13.12 ± 1.27	13.27 ± 0.08	12.98 ± 0.15	0.055

Notes: Group A, patients with COPD; Group B, healthy people.

Abbreviations: COPD, chronic obstructive pulmonary disease; RBC, red blood cell; Hb, hemoglobin; PLT, platelet; Lym, lymphocyte; RCI, red cell index; NLR, neutrophil–lymphocyte ratio; PLR, platelet–lymphocyte ratio; RDW, red blood cell distribution width.

Table 2 T-Tests for Groups Divided According to RCI with Severity of Disease and Other Functions

	RCI < 1.75 (n = 54)	RCI > 1.75 (n = 46)	p
Baseline characteristic
Age	69.67 ± 9.46	71.28 ± 7.38	0.340
Sex (male, n%)	40 (74.07)	42 (91.30)	0.021
Duration of Disease	10.13 ± 8.69	15.69 ± 13.55	0.021
Smoking	36 (66.67)	38 (82.61)	0.054
Hypertension	22 (40.74)	16 (34.78)	0.545
Diabetes mellitus	9 (16.67)	6 (13.04)	0.617
Lung Function
FEV1 (L)	1.05 ± 0.49	0.84 ± 0.34	0.016
FVC (L)	1.97 ± 0.73	1.67 ± 0.54	0.027
FEV1% (< 50%)	44.25 ± 14.88	34.10 ± 12.57	0.001
FEV1/FVC ratio (%)	52.16 ± 9.63	49.46 ± 7.69	0.150
PaO2	73.21 ± 12.33	72.57 ± 17.47	0.838
PaCO2	42.44 ± 5.47	46.73 ± 11.39	0.025
Severity of disease
GOLD	2.76 ± 0.84	3.31 ± 0.64	0.001
BODE	3.56 ± 2.22	4.25 ± 2.45	0.165
ADO	4.41 ± 1.41	5.05 ± 1.38	0.033
DOSE	2.24 ± 1.64	3.21 ± 1.74	0.051
mMRC	1.58 ± 0.97	1.77 ± 0.96	0.343
CAT	17.45 ± 6.64	18.18 ± 6.91	0.601
SGQR	36.30 ± 19.82	39.42 ± 2.55	0.415

Abbreviations: RCI, red cell index; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; FEV₁%, forced expiratory volume in 1 second in percent of the predicted value; PaO₂, partial pressure of oxygen in arterial blood; PaCO₂, partial pressure of carbon dioxide in arterial blood; GOLD, Global Initiative for Chronic Obstructive Lung Disease; BODE, BMI, airflow obstruction, dyspnea and exercise capacity; ADO, age, dyspnoea and obstruction; DOSE, dyspnoea, obstruction, smoking and exacerbations; mMRC, modified Medical Research Council dyspnoea scale; CAT, COPD assessment test; SGRQ, St. George’s Respiratory Questionnaire.

Figure 2 Correlations of the RCI, NLR and PLR with FEV₁%.

Notes: Correlations between RCI, NLR and PLR levels in COPD patients and FEV₁% were assessed by Pearson’s correlation test, RCI, r = −0.302, p = 0.004; NLR, r = −0.153, p = 0.148; and PLR, r = −0.098, p = 0.354.

Figure 3 ROC curves of the RCI, NLR, PLR, Lym and RDW of COPD patients, for predicting severe or mild COPD. The area under ROC curve of RCI: 0.729; 95% CI: 0.619–0.839; p = 0.001.

Table 3 Univariate Logistic Regression Analysis Assesses Different Prognostic Predictors of COPD

	OR	95% CI		p
Age	0.987	0.936–1.041		0.641
Sex	0.672	0.222–2.036		0.482
Duration of Disease	1.071	1.006–1.139		0.031
Smoking	1.067	0.369–3.081		0.905
Hypertension	0.937	0.383–2.291		0.887
BMI	0.861	0.760–0.977		0.020
CAT	1.034	0.969–1.104		0.315
SGRQ	1.027	1.001–1.055		0.043
CCQ	1.096	0.997–1.204		0.059
ADO	1.652	1.171–2.333		0.004
DOSE	2.945	1.418–6.113		0.004
FEV1/FVC	0.801	0.731–0.878		<0.001
PaO2	0.970	0.941–1.000		0.051
PaCO2	1.380	1.175–1.620		<0.001
RBC	1.811	0.627–5.231		0.273
Hb	1.019	0.985–1.054		0.284
PLT	0.994	0.988–1.000		0.066
Lym	0.265	0.116–0.602		0.002
RCI	2.533	1.378–4.656		0.003
NLR	1.380	1.038–1.836		0.027
PLR	1.006	0.999–1.013		0.082
RDW	1.038	0.605–1.781		0.893

Notes: Divided COPD patients into two groups according to GOLD stage: Group A, GOLD I + GOLD II; Group B, GOLD III + GOLD IV. Using univariate logistic regression analysis to assess the effect of prognostic indicators on the severity of COPD.

Abbreviations: BMI, body mass index; CAT, COPD assessment test; SGRQ, St. George’s Respiratory Questionnaire; CCQ, Clinical COPD Questionary; ADO, age, dyspnea and airflow obstruction; DOSE, MRC Dyspnea Scale, airflow obstruction, smoking status and exacerbations; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; PaO₂, partial pressure of oxygen in arterial blood; PaCO₂, partial pressure of carbon dioxide in arterial blood; RBC, red blood count; Hb, hemoglobin; PLT, platelet; Lym, lymphocyte; RCI, red cell index; NLR, neutrophil–lymphocyte ratio; PLR, platelet–lymphocyte ratio; RDW, red blood cell distribution width.

Table 4 Adjusted Odds Ratio (95% Confidence Interval) for Severe COPD (GOLD III + IV)

	OR (95% CI)	p
Model1	2.533 (1.378–4.656)	0.003
Model2	2.348 (1.239–4.450)	0.009
Model3	4.272 (1.570–11.627)	0.004

Notes: Model 1 is univariate analysis. Model 2 is adjusted by age, sex, duration of disease and body mass index. Model 3 is adjusted by age, sex, duration of disease, BMI, FEV₁/FVC and PaCO₂.