Table 2.
Underlying Medical Conditions and Behaviors of Influenza A(H7N9) Cases and Controls Matched by Age, Sex, and Location in China, October 2014 to April 2015
| Characteristics | Cases (n = 85) No. (%) | Controls (n = 334) No. (%) | mOR (95% CI) | P Value |
|---|---|---|---|---|
| Obesity, n (%)a | 5 (6) | 11 (3) | 1.9 (.62–5.7) | .27 |
| ≥1 chronic disease, n (%)b | 39 (46) | 84 (25) | 3.2 (1.8–5.7) | <.01 |
| COPD | 8 (9) | 9 (3) | 3.7 (1.4–9.9) | <.01 |
| Other pulmonary disease (tuberculosis, asthma) | 4 (5) | 3 (1) | 5.3 (1.2–23.8) | .03 |
| Cardiovascular disease | 27 (32) | 70 (21) | 2.0 (1.1–3.7) | .02 |
| Diabetes | 10 (12) | 16 (5) | 3.0 (1.2–7.3) | .02 |
| Kidney disease | 2 (2) | 1 (0.3) | 8.0 (.72–89.6) | .09 |
| Rheumatoid arthritis | 1 (1) | 3 (0.9) | 1.3 (.14–12.8) | .81 |
| Cancer (all types) | 0 (0) | 1 (0.3) | — | — |
| Hepatic disease | 7 (8) | 0 (0) | — | — |
| Immunosuppressive medications, n (%)c | 3 (4) | 1 (0.3) | 12.2 (1.3–118.6) | .03d |
| Current/pervious smoker n (%)e | 21 (25) | 132 (40) | 0.32 (.16–.65) | <.01 |
| Handwashing frequency, n (%)f | ||||
| Occasionally | 27 (32) | 23 (7) | Ref | |
| Sometimes | 32 (38) | 54 (16) | 0.67 (.34–1.4) | .26 |
| Often | 26 (31) | 257 (77) | 0.06 (.03–.14) | <.01 |
| Uses soap to wash hands, n (%) | 12 (14) | 180 (54) | 0.10 (.05–.23) | <.01 |
Boldface indicates statistical significance with P < .05, and those variables with P < .10 were included in multivariate analyses for the initial model.
Abbreviations: BMI, body mass index; CI, confidence interval; COPD, chronic obstructive pulmonary disease; mOR, matched odds ratio; Ref, reference category.
a Adults ≥18 years of age were considered obese if their BMI was ≥30 kg/m2; children <18 years were considered obese if their BMI-for-age was ≥95th percentile. BMI was calculated using self-reported height and weight.
b Chronic diseases included COPD, other pulmonary diseases including tuberculosis and asthma, cardiovascular disease, diabetes, kidney disease, and rheumatoid arthritis. Tumor and hepatic disease were also included in the investigation but cannot be analyzed because of the small value. All chronic diseases were diagnosed by medical institutions at the county level or above. Hypertension and hypercholesterolemia were not included as chronic diseases in this analysis.
c Immunosuppressive medication was prednisone.
d Nonconditional logistical regression was used because of limited sample size.
e We defined smoking status by asking participants to choose one of the following categories: “never smoked”, “currently smoke”, or “smoked in past, but quit”. Those who chose “currently smoke” or “smoked in past, but quit” were defined as current/previous smokers.
f Handwashing habit was defined as the frequency of handwashing per 10 times of contact/exposure to poultry (occasionally, <5 times; sometimes, 5–8 times; often, >8 times).