Volume 16, Number 10—October 2010
Letter
Underlying Medical Conditions and Hospitalization for Pandemic (H1N1) 2009, Japan
Taro Tomizuka
, Yoshihiro Takayama, Tokuaki Shobayashi, Yasumasa Fukushima, and Yasuhiro Suzuki
, Yoshihiro Takayama, Tokuaki Shobayashi, Yasumasa Fukushima, and Yasuhiro SuzukiTable
Age-specific incidence and risk for hospitalization with laboratory-confirmed pandemic (H1N1) 2009 virus infection, Japan, July 28–December 14, 2009*
| Patient characteristic | Underlying medical conditions† |
No underlying medical conditions‡ |
RR | AR | |||
|---|---|---|---|---|---|---|---|
| No. (%) patients | Incidence/100,000§ | No. (%) patients | Incidence/100,000§ | ||||
| Age group, y | |||||||
| 0–4 | 648 (22.1) | 195.2 | 2,285 (77.9) | 45.2 | 4.3 | 150.0 | |
| 5–9 | 1,848 (32.6) | 814.1 | 3,822 (67.4) | 69.4 | 11.7 | 744.7 | |
| 10–14 | 763 (35.2) | 573.7 | 1,406 (64.8) | 24.0 | 23.9 | 549.6 | |
| 15–19 | 173 (38.9) | 219.0 | 272 (61.1) | 4.5 | 48.4 | 214.5 | |
| 20–29 | 110 (43.8) | 53.9 | 141 (56.2) | 1.0 | 54.9 | 52.9 | |
| 30–39 | 105 (49.8) | 28.5 | 106 (50.2) | 0.6 | 48.4 | 27.9 | |
| 40–49 | 125 (61.6) | 21.6 | 78 (38.4) | 0.5 | 43.5 | 21.1 | |
| 50–59 | 176 (76.9) | 12.8 | 53 (23.1) | 0.3 | 38.3 | 12.5 | |
| 60–69 | 148 (77.5) | 6.7 | 43 (22.5) | 0.3 | 24.0 | 6.5 | |
| >70 |
324 (81.0) |
8.2 |
76 (19.0) |
0.5 |
17.9 |
7.8 |
|
| Gender¶ | |||||||
| M | 2,857 (35.3) | NA | 5,236 (64.7) | NA | |||
| F |
1,563 (33.9) |
NA |
3,046 (66.1) |
NA |
|||
| *RR, relative risk for hospitalization; AR, attributable risk for hospitalization; NA, not available. Medical conditions defined as chronic respiratory diseases, chronic cardiovascular diseases, chronic renal diseases, chronic liver diseases, neurologic diseases, hematologic diseases, diabetes, and immunosuppression (including malignant neoplasm) and chronic childhood diseases. †n = 4,420 (43.8%); 83 patients died. ‡n = 8,282 (65.2%); 27 patients died. §Incidence = no. case-patients with pandemic (H1N1) 2009 virus infection and a particular medical condition/total population having the same medical condition (e.g., population 0–4 years of age with medical condition). ¶p value for difference in gender was 0.11, obtained by χ2 test (2-sided) for testing the null hypothesis. | |||||||
