Volume 17, Number 10—October 2011
Research
Pandemic (H1N1) 2009 among Quarantined Close Contacts, Beijing, People’s Republic of China
Table 4
Factors significantly associated with infection of pandemic (H1N1) 2009 virus in close contacts in multivariate analysis*
| Factor | All close contacts† | Flight passenger contacts‡ | Nonflight passenger contacts§ | |||||
|---|---|---|---|---|---|---|---|---|
| OR (95% CI) | p value | OR (95% CI) | p value | OR (95% CI) | p value | |||
| Age of close contacts, y | ||||||||
| >50 | Reference | Reference | Reference | |||||
| 20–50 | 3.42 (1.56–7.48) | 0.002 | 3.13 (0.40–24.76) | 0.280 | 2.89 (1.23–6.80) | 0.015 | ||
| 0–19 | 7.76 (3.52–17.09) | <0.001 | 13.33 (1.77–100.22) | 0.012 | 4.97 (2.06–12.00) | <0.001 | ||
| Relationship to index case-patient | ||||||||
| Nonhousehold member | Reference | NA | Reference | |||||
| Household member | 3.83 (2.65–5.53) | <0.001 | NA | NA | 2.37 (1.58–3.55) | <0.001 | ||
| Type of exposure to index case-patient | ||||||||
| During asymptomatic phase¶ | Reference | Reference | Reference | |||||
| During symptomatic phase | 1.86 (1.23–2.80) | 0.003 | NA | NA | 1.79 (1.09–2.93) | 0.021 | ||
| Exposure duration of close contacts, h | ||||||||
| <12 | Reference | Reference | Reference | |||||
| >12 | 1.83 (1.25–2.67) | 0.002 | 3.41 (1.49–7.78) | 0.004 | NA | NA
*Variables with p<0.1 in Table 2 were included in multivariate unconditional logistic regression analysis. Hosmer-Lemeshow goodness-of-fit test was used to assess the model fit for logistic regression. OR, odd ratio; CI, confidence interval; NA, not available, indicating not included in the final model. *Variables with p<0.1 in Table 2 were included in multivariate unconditional logistic regression analysis. Hosmer-Lemeshow goodness-of-fit test was used to assess the model fit for logistic regression. OR, odd ratio; CI, confidence interval; NA, not available, indicating not included in the final model. | ||
*Variables with p<0.1 in Table 2 were included in multivariate unconditional logistic regression analysis. Hosmer-Lemeshow goodness-of-fit test was used to assess the model fit for logistic regression. OR, odd ratio; CI, confidence interval; NA, not available, indicating not included in the final model.
†One dependent variable (infection with pandemic [H1N1] 2009 virus) and 5 independent variables (age of index case-patient, type of exposure to index case-patients, age of close contacts, relationships to index case-patients, and exposure duration of close contacts) were included in multivariate analysis. One independent variable (age of index case-patient) was removed in the stepwise regression equation. The goodness-of-fit test suggested that the logistic regression model fitted well (p = 0.631).
‡One dependent variable (infection with pandemic [H1N1] 2009 virus) and 4 independent variables (age of index case-patient, type of exposure to index case-patient, age of close contacts, and exposure duration of close contacts) were included in multivariate analysis. Two independent variables (age of index case-patient and type of exposure to index case-patient) were removed in the stepwise regression equation. The goodness-of-fit test suggested that the logistic regression model fitted well (p = 0.982).
§One dependent variable (infection with pandemic [H1N1] 2009 virus) and 5 independent variables (age of index case-patient, type of exposure to index case-patient, age of close contacts, relationships to index case-patient, and exposure duration of close contacts) were included in multivariate analysis. Two independent variables (age of index case-patient and exposure duration of close contacts) were removed in the stepwise regression equation. The goodness-of-fit test suggested the logistic regression model fitted well (p = 0.751).
¶Exposed to symptomatic index case-patients before their illness onset or exposed to index case-patients who had subclinical infections.
1These authors contributed equally to this article.