Age and Gender Adjusted Comparison of Clinical Features between Severe Cases Infected with H7N9 and H1N1pdm Influenza A in Jiangsu Province, China

<div><p>Background</p><p>Influenza H7N9 and H1N1pdm can cause severe human infections. It is important to investigate the distinguishing clinical features between these two diseases. Several studies have compared the differences in general, however, age and gender adjusted comparisons may be more useful and informative to the health professionals.</p><p>Methods</p><p>A total of 184 severe H1N1pdm patients and 37 severe H7N9 patients from Jiangsu Province were included in this analysis to perform age and gender adjusted comparison of clinical features.</p><p>Results</p><p>After adjusting age and gender, no significant differences in chronic medical conditions or treatment were found between severely ill patients with H7N9 and H1N1pdm. Severely ill patients with H7N9 had significantly longer interval from onset of illness to neuraminidase inhibitor treatment and to death. They were more likely to have complications such as acute respiratory distress syndrome (ARDS), liver and renal dysfunctions, and had a significantly higher risk of death.</p><p>Conclusion</p><p>Our results suggests that age and gender should be adjusted as important confounding factors when comparing the clinical features between severe H7N9 and H1N1pdm patients to avoid any misunderstanding regarding the differences between these two diseases particularly in terms of clinical severity and prognosis.</p></div

Age distribution of severe patients infected with influenza H7N9 and H1N1pdm in Jiangsu Province, China.

<p>Age distribution of severe patients infected with influenza H7N9 and H1N1pdm in Jiangsu Province, China.</p

Distribution of selected variables between severe H7N9 and H1N1pdm patients.

<p>^a Patients with missing data were excluded for each variable.</p><p>^b Pearson chi-square test was used for comparing proportions and continuity correction or Fisher’s Exact Test was used if appropriate. Mann-Whitney U test was used for comparing medians.</p><p>^c Age and gender were adjusted using General Linear Model (for BMI) or Cox proportional hazards model (for selected time durations) for continuous variables and Logistic regression model for categorical variables.</p><p>^d Interquartile range (IQR), Frequency (FREQ), Body mass index (BMI)</p><p>Distribution of selected variables between severe H7N9 and H1N1pdm patients.</p

Phylogenetic analyses of the NoV GII.P16-GII.2 sequences based on partial RdRp and full length capsid regions (VP1).

<p>(<b>A</b>) Phylogenetic tree of a 1061 bp region of RdRp. (<b>B</b>) Phylogenetic tree of a 1629bp region ofVP1. The trees were constructed using the Neighbor-Joining analysis and the evolutionary distances were computed using the Kimura 2-parameterþG method available in MEGA v7.0. Bootstrap values (>90%) are shown as percentages derived from 1,000 samplings at the nodes of the tree. The scale bars represent the number of nucleotide substitutions per site. The norovirus strains reported in this study were marked with solid black triangles.</p

List of primers used in the study.

<p>List of primers used in the study.</p

Norovirus outbreaks in Jiangsu, China.

<p>(<b>A</b>) Laboratory confirmed number of monthly NoV outbreaks occurring in Jiangsu province, China from December 2016 through March 2017. (<b>B</b>) Distribution of norovirus genotypes detected in Jiangsu from December 2016 through March 2017.</p

Amino acid differences between 29 NoV strains in the RdRp region.

<p>Green regions indicate the conserved residues organized into motifs involved in enzymatic activities. Dashes indicate lack sequence information. P16-16 represents GII.P16-GII.16 strain and P16-2 represents GII.P16-GII.2 strain.</p

Phylogenetic analyses of the NoV GII.P16-GII.2 sequences based on partial RdRp and full length capsid regions (VP1).

<p>(<b>A</b>) Phylogenetic tree of a 1061 bp region of RdRp. (<b>B</b>) Phylogenetic tree of a 1629bp region ofVP1. The trees were constructed using the Neighbor-Joining analysis and the evolutionary distances were computed using the Kimura 2-parameterþG method available in MEGA v7.0. Bootstrap values (>90%) are shown as percentages derived from 1,000 samplings at the nodes of the tree. The scale bars represent the number of nucleotide substitutions per site. The norovirus strains reported in this study were marked with solid black triangles.</p

Sampling times and epidemic curve.

<p>Sampling times of serologic survey (Jan 1–Mar 28, 2010) shown relative to epidemic curve of pH1N1 cases and percent of ILI (influenza-like illness, ILI %) accounted for out-patient and emergency cases.</p

Seropositive rates of antibodies against pH1N1 in pregnant women and voluntary blood donors at the 4 sampling times.

<p>Seropositive rates, Proportion of titers of 1∶40 or more (%).</p><p>*Chi square tests.</p>†<p>Cochran-Armitage test.</p