1. Study Population
During the study period, 158 patients were enrolled in this study. All patients had B pertussis DNA detected by PCR in nasopharyngeal secretions or in sputum. The demographic, clinical, and laboratory data of the study patients are shown in Table 1.
Table 1
Group | Group A | Group B | Group C | total(n = 158) | P-value |
WBC(*10^9/L) | 30 ≤ WBC༜50 (n = 80) | 50 ≤ WBC༜70 (n = 55) | 70 ≤ WBC(n = 23) |
Demographics | | | | | |
Gender(male,n,%) | 42(52.5%) | 24(43.6%) | 5(21.7%) | 71(44.9%) | 0.032 |
Death(n,%) | 0(0%) | 2(3.6%) | 10(43.5%) | 12(7.6%) | 0.000 |
Any DTaP | 0(0–3) | 0(0–3) | 0(0–1) | 0(0–3) | 0.479 |
Age of onset(d) | 150(88-285.25) | 136(69–435) | 134(84–300) | 145.5(81.5–318) | 0.78 |
days from onset to admission(d) | 15(11.25–19.75) | 14(7–19) | 15(6–18) | 15(10–19) | 0.312 |
Clinical Characteristics and Complications | | | | | |
whooping(n,%) | 28(35%) | 20(37%) | 13(56.5%) | 61(38.9%) | 0.166 |
Cyanosis(n,%) | 36(45%) | 32(58.2%) | 18(78.3%) | 86(54.4%) | 0.015 |
Wheezing(n,%) | 34(42.5%) | 31(56.4%) | 15(65.2%) | 80(50.6%) | 0.091 |
Fever(n,%) | 33(41.3%) | 33(60%) | 21(91.3%) | 87(55.1%) | 0.000 |
Highest Temperature (°Celcius) | 38.35(37.8–39) | 38.4(37.975–38.925) | 38.9(38.3-39.05) | 38.5(38–39) | 0.114 |
Highes heart rate(beats/min) | 144(136.5–161) | 157(148.75-172.25) | 187.5(166.75-201.25) | 158(140.5–180) | 0.000 |
Highes respiratory rate(breaths/min) | 53.9 ± 11.46 | 59.4 ± 12.33 | 69.04 ± 14.08 | 58.94 ± 13.46 | 0.000 |
Pneumonia (n,%) | 42(52.5%) | 29(52.7%) | 3(13%) | 74(46.8%) | 0.002 |
Severe pneumonia(n,%) | 16(20%) | 23(41.8%) | 20(87%) | 59(37.3%) | 0.000 |
Respiratory failure(n,%) | 15(18.8%) | 23(41.8%) | 20(87%) | 58(36.7%) | 0.000 |
Lung consolidation or atelectasis(n,%) | 14(20.6%) | 21(39.6%) | 16(69.6%) | 51(35.4%) | 0.000 |
Pulmonary hypertension(n,%) | 2(6.7%) | 3(10.3%) | 5(26.3%) | 10(12.8%) | 0.190 |
Heart faliure(n,%) | 2(2.5%) | 2(3.6%) | 13(56.5%) | 17(10.8%) | 0.000 |
Pertussis encephalopathy(n,%) | 1(1.3%) | 7(12.7%) | 6(26.1%) | 14(9%) | 0.000 |
Laboratory Findings | | | | | |
Abnormal myocardial markers(n,%) | 11(13.8%) | 12(21.8%) | 10(43.5%) | 33(20.9%) | 0.013 |
elevated alanine aminotransferase(n,%) | 16(20%) | 9(16.4%) | 18(78.3%) | 43(27.2%) | 0.000 |
Increased C-reactive protein(n,%) | 5(6.3%) | 14(25.5%) | 16(69.6%) | 35(22.2%) | 0.000 |
Increased procalcitonin(n,%) | 33(44%) | 27(50%) | 18(81.8%) | 78(51.7%) | 0.007 |
Days to highest WBC count, median (IQR) | 15(13.25-20) | 14(10–17) | 15(7–18) | 15(11–19) | 0.043 |
Combined bacterial infection(n,%) | 28(35.9%) | 25(46.3%) | 19(82.6%) | 72(46.5%) | 0.000 |
Combined virus infection(n,%) | 14(17.9%) | 16(29.1%) | 8(34.8%) | 38(24.4%) | 0.152 |
Treatment | | | | | |
days from illness onset to Macrolide plus treatment (d) | 12(7–15) | 12(8–15) | 10(5–15) | 12(7–15) | 0.465 |
Total course of macrolides(d) | 8(6–9) | 8(7–11) | 9(6–11) | 8(6–10) | 0.366 |
Received Gamma globulin(n,%) | 14(17.7%) | 27(49.1%) | 12(52.2%) | 53(33.8%) | 0.000 |
Received steroids(n,%) | 18(22.5%) | 18(32.7%) | 8(34.8%) | 43(27.2%) | 0.31 |
Received Vasoactive drugs(n,%) | 1(1.3%) | 4(7.3%) | 14(60.9%) | 19(12%) | 0.000 |
Received Other antibiotics(n,%) | 50(62.5%) | 44(80%) | 22(95.7%) | 116(73.4%) | 0.003 |
Received Exchange transfusion(n,%) | 0(0%) | 5(9.1%) | 12(52.2%) | 17(10.8%) | 0.000 |
ICU admission(n,%) | 5(6.3%) | 10(18.2%) | 21(91.3%) | 36(22.8%) | 0.000 |
48 hours of ICU admission(n,%) | 2(40%) | 6(60%) | 15(71.4%) | 23(63.9%) | 0.380 |
ICU length of stay (days) | 9(5.5–16) | 17(5.5–23.5) | 7(2.5–17.5) | 9(3–18) | 0.218 |
Mechanical ventilation use(n,%) | 6(7.7%) | 16(29.6%) | 19(82.6%) | 41(26.5%) | 0.000 |
Intubation(n,%) | 4(66.7%) | 8(47.1%) | 18(85.7%) | 30(68.2%) | 0.033 |
Length of invasive ventilation (hours) | 212.5(156.25-295.75) | 330(96-457.5) | 151.5(40-343.5) | 160(53–330) | 0.371 |
Improvement after treatment | | | | | |
Days hospitalized, median (IQR) | 9(6–13) | 12(9–16) | 16(3–27) | 10.5(7–15) | 0.011 |
Days until cough relief, median (IQR) | 23(17-27.75) | 25.5(21–31) | 29(24.5–37) | 25(19-30.5) | 0.013 |
Days until the WBC fell below 25*10^9/L, median (IQR) | 6(4–7) | 9(7-12.75) | 12(9-13.25) | 7(5–10) | 0.013 |
There were 80 (50.6%) patients with 30*10^9/L ≤ WBC < 50*10^9/L, 55 (34.8%) patients with 50*10^9/L ≤ WBC < 70*10^9/L, and 23 (14.6%) patients with WBC ≥ 70*10^9/L. There were 52.5% males in group A, 43.6% in group B, and 21.7% in group C, and there were significant differences among the three groups (P = 0.032).
There were 12 patients who died in the study, 10 (43.5%) patients in group C, and only 2 (3.6%) patients in group B. No patient died in group A. There were significant differences in the mortality rate among the three groups (P = 0.000).
In the three groups, there were no significant differences in the times of vaccination, age of onset, or time from onset to admission (P = 0.479, 0.78, 0.312, respectively).
2. Clinical manifestations and complications
Clinical manifestations and complication data are shown in Table 1. Regarding the clinical manifestations, there were no significant differences in the incidence of whooping and wheezing (P = 0.166, 0.091). The incidence of cyanosis was 36 (45%) in group A, 32 (58.2%) in group B, and 18 (78.3%) in group C, with significant differences (P = 0.015). There were significant differences among the three groups (P = 0.015). The incidence of fever in group A was 33 (41.3%), the incidence in group B was 33 (60%), and in the incidence in group C was 21 (91.3%); there was a significant difference (P = 0.000). However, there were no significant differences in the highest temperature of fever among the three groups (P = 0.114). The highest heart rate (beats/min) in group A was 144 (136.5–161), in group B was 157 (148.75-172.25), in group C was 187.5 (166.75-201.25); the difference was statistically significant (P = 0.000). The highest respiratory rate (breaths/min) in group A was 53.9 ± 11.46, group B was 59.4 ± 12.33, and group C was 69.04 ± 14.08; the difference was also statistically significant (P = 0.000).
Regarding complications, the number of pneumonia cases was 42 (52.5%) in group A, 29 (52.7%) in group B and 3 (13%) in group C; the difference was statistically significant (P = 0.002). The number of severe pneumonia cases in group A was 16 (20%), that in group B was 23 (41.8%), and that in group C was 20 (87%); the difference was statistically significant (P = 0.002). The incidence of pneumonia and severe pneumonia was 72.5% in group A, 94.5% in group B, and 100% in group C. The incidence of complications such as respiratory failure, pulmonary consolidation or atelectasis, pulmonary hypertension, heart failure, and pertussis encephalopathy all increased with the increased WBC. The incidence rates of all complications were significantly different among the three groups (P = 0.000, 0.000, 0.000, 0.000, respectively), except for pulmonary hypertension among the three groups (P = 0.190).
3. Laboratory Data
Laboratory data are presented in table 1. On organ function assessment, the incidence of abnormal myocardial markers in group A was 13.8% (n=11), the incidence in group B was 21.8% (n=12), and the incidence in group C was 43.5% (n=10); the incidence of abnormal liver function in group A was 20% (n=16), the incidence in group B was 16.4% (n=9), and the incidence in group C was 78.3% (n=18). The incidence of myocardial and liver function abnormalities in the three groups were significantly different (P=0.013, 0.000).
In the examination of inflammatory indicators, the number of patients with increased CRP in group A was 5 (6.3%), in group B was 14 (25.5%), and in group C was 16 (69.6%); the number of patients with increased procalcitonin (PCT) in group A was 33 (44%).), in group B was 27 (50%), and in group C was 18 (81.8%). of the incidence of increased CRP and PCT were significantly different among the three groups (P=0.000, 0.007).
In the pathogenic examinations, 28 (35.9%) cases in group A were combined with bacterial infection and 14 (17.9%) were combined with viral infection; the numbers of cases combined with bacterial infection and viral infection were 25 (46.3%) and 16 (29.1%) in group B, and 19 (82.6%) and 8 (34.8%) in group C, respectively. The difference in combined bacterial infections among the three groups was statistically significant (P=0.000), but there was no significant difference in the incidence of combined viral infections (P=0.152).
4. Treatment
There was no significant difference in the days from illness onset to macrolide plus treatment or the total course of macrolides among the three groups of patients (P=0.465, 0.366). The incidence of gamma globulin, steroids, vasoactive drugs, other antibacterial drugs, and ET increased gradually with increasing WBC levels among the three groups, with the exception of steroid use (P=0.31), there were significant differences among the groups (P =0.000, 0.000, 0.003, and 0.000).
The number of patients admitted to the ICU was 5 (6.3%) in group A, 10 (18.2%) in group B, and 21 (91.3%) in group C. There was a significant difference in the rate of ICU admission within 48 hours of hospital admission among the three groups (P=0.000). Although the rate of admission to the ICU within 48 hours after hospital admission also increased with the increase in white blood cell count, there was no significant difference in the rate of admission to the ICU within 48 hours of hospital admission among the three groups (P=0.380).
5.Improvement after treatment
The length of hospital stay in group A was 9 days (6-13), in group B was 12 days (9-16), and in group C was 16 days (3-27). The number of days until cough relief in group A was 23 (17-27.75), in group B was 25.5 (21-31), and in group C was 29 (24.5-37). The number of days until the WBC fell below 25*10^9/L in group A was 6 (4-7), in group B was 9 (7-12.75), and in group C was 12 (9-13.25). The length of the hospital stay, the number of days until cough relief and the number of days until the WBC fell below 25*10^9/L were all prolonged as the WBC level increased, and the difference was statistically significant (P=0.011, 0.013, 0.013, respectively), as shown in Table 1.
6. Timing of Exchange transfusion
Seventeen patients received exchange transfusion, 12 (52.2%) patients had WBCs exceeding 70*10^9/L, and 5 (9.1%) patients had 50*10^9/L≤WBC<70*10^9/L. No patient received exchange transfusion in the 30*10^9/L≤ WBC<50*10^9/L group.
The area under the receiver operating characteristic (ROC) curve (AUC) value for WBC count with the cutoff point of 55.38 *10^9/L was 0.899 (95% confidence interval (CI), 0.834~0.963,P=0.000) in predicting exchange transfusion. When applying the ROC curve with the WBC count cutoff point of 55.38 *10^9/L, the analysis yielded 88.2% sensitivity and 23.4% specificity (Figure 1). The area under the receiver operating characteristic (ROC) curve (AUC) value for respiratory rate with a cutoff point of 59 breaths/min was 0.795 (95% confidence interval (CI), 0.699~0.891,P=0.000) in predicting exchange transfusion. When applying an ROC curve with the respiratory rate cutoff point of 59 breaths/min, the analysis yielded 94.1% sensitivity and 36.7% specificity (Figure 2). The area under the receiver operating characteristic (ROC) curve (AUC) value for heart rate with a cutoff point of 159 beats/min was 0.813 (95% confidence interval (CI), 0.731~0.895,P=0.000) in predicting exchange transfusion. When applying the ROC curve with heart rate at the cutoff point of 159 beats/min, the analysis yielded 100% sensitivity and 38.1% specificity (Figure 3).