Journal List > Pediatr Allergy Respir Dis > v.21(4) > 1033137

Kang, Kim, Kim, An, Yun, Choi, and Jung: Comparisons of Clinical Features among Influenza A (H1N1) and Seasonal Influenza A and B during 2009 to 2010 at a Single Institution

Abstract

Purpose

This study was performed to compare the clinical features of pediatric patients who were diagnosed with influenza A (H1N1) or seasonal influenza A and B during 2009 and 2010 at a single institution.

Methods

Among children who visited the Dong-A University Hospital with fever (>37.8) and ℃ acute respiratory symptoms from September 2009 to February 2010, 1,004 children who were diagnosed with influenza A (H1N1) or seasonal influenza A and B by reverse transcription-polymerase chain reaction (RT-PCR) were enrolled. Monthly incidence, fever duration before diagnosis, symptoms (fever, cough, rhinorrhea, sore throat, headache, vomiting, abdominal pain, diarrhea, seizure, and dyspnea) and signs (rales, wheezing) were reviewed retrospectively in each group based on medical records.

Results

Influenza A (H1N1) was detected in 944 patients (94.0%), followed by seasonal influenza A in 42 (4.2%) and seasonal influenza B in 8 (1.8%). The positive rate of influenza infection was highest in November 2009 (n=557, 55.5%). Mean duration of fever before RT-PCR was 1.6 days (range, 1.5 to 1.8 days). Except fever, cough was the most common symptom (n=792, 78.9%), followed by rhinorrhea in 407 patients (40.5%). Rales and wheezing were detected in 16 patients (1.6%) and 19 (1.9%), respectively. Significant differences were observed for the number of patients who had cough, headache, vomiting, and wheezing among the three groups (P<0.05).

Conclusion

Although the incidence of cough, headache, vomiting, and wheezing differed significantly among the three groups, the number of patients in each group was too different to compare the results.

References

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Table 1.
Monthly Distribution of the Influenza Viruses
Mo/Yr Influenza A (H1N1) Influenza A (other) Influenza B Total
Sep./09 14 (1.4) 2 (0.2) 0 (0) 16
        (1.6)
Oct./09 220 (21.9) 4 (0.4) 1 (0.1) 225
        (22.4)
Nov./09 524 (52.2) 32 (3.2) 1 (0.1) 557
        (55.5)
Dec./09 164 (16.3) 2 (0.2) 1 (0.1) 167
        (16.6)
Jan./10 21 (18.4) 1 (0.1) 9 (0.9) 31
        (3.1)
Feb./10 1 (0.1) 1 (0.1) 6 (0.6) 8
        (0.8)
Total 944 (94.0) 42 (4.2) 18 (1.8) 1,004
        (100)

Values are presented as no. of positive cases (%).

Table 2.
Age, Sex Distribution and Fever Duration before Reverse Transcription-Polymerase Chain Reaction
  Influenza A(H1N1) (n=944) Influenza A(other) (n=42) Influenza B (n=18) Total (n=1,004) P -value
Sex, M: F 533:411 (1.3:1) 29:13 (2.2:1) 9:9 (1:1) 571:433 (1.3:1)
Age, yr (range) 7.0 (6.8–7.3) 6.4 (4.9–7.8) 6.7 (4.6–8.9) 6.9 (5.9–7.4) 0.558
Fever, day (range) 1.6 (1.5–1.7) 1.7 (1.2–2.2) 2.8 (2.1–3.4) 1.6 (1.5–1.8) 0.000

Values are presented as 95% confidence interval.

By Kruskal-Wallis test among 3 groups.

Table 3.
Percentage of Symptoms and Signs in 3 Groups
Symptoms & sings Patients Influenza A(H1N1) n=944 (%) Influenza A(other) n=42 (%) Influenza B n=18 (%) Total n (%) P-value
Cough Overall 756 (80.1) 23 (54.8) 13 (72.2) 792 (78.9) <0.0001
  Subgroup 756 (80.1) 23 (54.8) 779 (80.0) <0.0001
    756 (80.1) 13 (72.2) 769 (79.9) 0.381
    23 (54.8) 13 (72.2) 36 (59.4) 0.408
Rhinorrhea Overall 385 (40.8) 14 (33.3) 8 (44.4) 407 (40.5) 0.614
  Subgroup 385 (40.8) 14 (33.3) 399 (40.5) 0.422
    385 (40.8) 8 (44.4) 393 (40.9) 0.811
    14 (33.3) 8 (44.4) 22 (36.7) 0.560
Sore throat Overall 227 (24.0) 7 (16.7) 8 (44.4) 242 (24.1) 0.074
  Subgroup 227 (24.0) 7 (16.7) 234 (23.7) 0.354
    227 (24.0) 8 (44.4) 235 (24.4) 0.055
    7 (16.7) 8 (44.4) 15 (25.0) 0.048
Headache Overall 178 (18.9) 4 (9.5) 7 (38.9) 189 (18.8) 0.034
  Subgroup 178 (18.9) 4 (9.5) 182 (18.5) 0.156
    178 (18.9) 7 (38.9) 185 (19.2) 0.061
    4 (9.5) 7 (38.9) 11 (18.3) 0.012
Vomiting Overall 59 (6.3) 8 (19.0) 3 (16.7) 70 (7.0) 0.003
  Subgroup 59 (6.3) 8 (19.0) 67 (6.8) 0.005
    59 (6.3) 3 (16.7) 62 (6.4) 0.104
    8 (19.0) 3 (16.7) 11 (18.3) 1.000
Abdominal pain Overall 50 (5.3) 1 (2.4) 0 (0) 51 (5.1) 0.707
  Subgroup 50 (5.3) 1 (2.4) 51 (5.2) 0.731
    50 (5.3) 0 (0) 50 (5.2) 0.626
    1 (2.4) 0 (0) 1 (1.7) 0.707
Diarrhea Overall 22 (2.3) 1 (2.4) 0 (0) 23 (2.3) 1.000
  Subgroup 22 (2.3) 1 (2.4) 23 (2.3) 1.000
    22 (2.3) 0 (0) 22 (2.3) 1.000
    1 (2.4) 0 (0) 1 (1.7) 1.000
Dyspnea Overall 8 (0.9) 0 (0) 0 (0) 8 (0.8) 1.000
  Subgroup 8 (0.9) 0 (0) 8 (0.8) 1.000
    8 (0.9) 0 (0) 8 (0.8) 1.000
    0 (0) 0 (0) 0 (0)
Seizure Overall 4 (0.4) 0 (0) 0 (0) 4 (0.4) 1.000
  Subgroup 4 (0.4) 0 (0) 4 (0.4) 1.000
    4 (0.4) 0 (0) 4 (0.4) 1.000
    0 (0) 0 (0) 0 (0)
Rales Overall 14 (1.5) 1 (2.4) 1 (5.6) 16 (1.6)) 0.159
  Subgroup 14 (1.5) 1 (2.4) 15 (1.5) 0.482
    14 (1.5) 1 (5.6) 15 (1.6) 0.249
    1 (2.4) 1 (5.6) 2 (3.3) 0.514
Wheezing Overall 14 (1.5) 2 (4.8) 3 (16.7) 19 (1.9) 0.001
  Subgroup 14 (1.5) 2 (4.8) 16 (1.6) 0.146
    14 (1.5) 3 (16.7) 17 (1.8) 0.003
    2 (4.8) 3 (16.7) 5 (8.3) 0.154

Values are presented as no. of positive cases (%).

By Fisher's exact test among groups; This is a retrospective study, and therefore significance level of alpha was not adjusted for multiple testing.

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