Bulletin of the World Health Organization

The population-based burden of influenza-associated hospitalization in rural western Kenya, 2007–2009

Daniel R Feikin, Maurice O Ope, Barrack Aura, James A Fuller, Stella Gikunju, John Vulule, Zipporah Ng’ang’a, M Kariuki Njenga, Robert F Breiman & Mark Katz

Volume 90, Number 4, April 2012, 256-263A

Table 5. Annual hospitalizations (per 100 000 population) associated with respiratory illness and influenza by age group, Bondo district, Kenya, June 2007–May 2009

Illness and age group Year 1a
Year 2b
Both years
Unadjusted
Adjustedc
Unadjusted
Adjustedc
Unadjusted
Adjustedc
No. (95% CI) No. (95% CI) No. (95% CI) No. (95% CI) No. (95% CI) No. (95% CI)
All age groups
Respiratory illness 722.3 NA 677.6 NA 699.8 NA
(690.8–753.8) (647.4–707.9) (678.0–721.6)
Influenza, A virus 29.9 53.5 33.2 47.1 31.6 50.3
(23.4–36.3) (44.9–62.1) (26.5–39.9) (39.1–55.1) (26.9–36.2) (44.4–56.1)
Influenza, B virus 1.4 2.4 8.5 9.8 5.0 6.1
(0.0–2.9) (0.6–4.2) (5.1–11.9) (6.2–13.4) (3.1–6.8) (4.1–8.2)
Influenza, A virus, B virus or both 31.3 55.8 41.4 56.5 36.4 56.2
(24.7–37.9) (47.0–64.6) (33.9–48.9) (47.7–65.3) (31.4–41.4) (50.0–62.4)
Influenza-associated hospitalizations (A, B or both virus types)
< 1 year 93.8 105.5 122.8 169.5 108.4 137.8
(40.7–146.8) (49.3–161.8) (62.7–182.9) (98.9–240.1) (68.3–148.5) (92.6–183.0)
1 year 204.0 406.3 100.2 122.5 151.6 263.1
(109.9–298.1) (273.6–539.0) (34.8–165.6) (50.1–194.8) (94.5–208.8) (187.9–338.3)
2 years 58.5 145.3 68.9 84.7 63.8 114.7
(7.2–109.8) (64.5–226.0) (13.8–124.1) (23.6–145.9) (26.1–101.4) (64.2–165.2)
3 years 60.6 163.9 59.5 67.0 60.1 115.0
(7.5–113.7) (76.6–251.2) (7.4–111.7) (11.6–122.3) (22.9–97.3) (63.5–166.5)
4 years 58.2 124.2 22.9 29.1 40.4 76.2
(7.2–109.3) (49.7–198.7) (0.0–54.6) (0.0–64.8) (10.5–70.3) (35.1–117.3)
< 5 years 95.7 182.4 79.4 105.6 87.5 143.7
(67.8–123.7) (143.8–221.0) (54.2–104.6) (76.5–134.7) (68.7–106.3) (119.6–167.8)
5–19 years 9.7 16.8 18.1 20.7 13.9 18.8
(4.0–15.4) (9.3–24.4) (10.4–25.9) (12.5–29.0) (9.1–18.7) (13.1–24.4)
20–34 years 28.1 33.6 58.9 76.5 43.6 55.2
(13.9–42.3) (18.0–49.1) (38.5–79.3) (53.2–99.7) (31.2–56.1) (41.2–69.2)
35–49 years 33.0 49.7 48.6 80.3 40.9 65.1
(12.6–53.5) (24.6–74.8) (24.0–73.2) (48.7–111.9) (24.9–56.9) (44.9–85.3)
≥ 50 years 19.2 55.0 34.6 59.5 27.0 57.3
(3.8–34.6) (29.0–81.1) (14.2–55.0) (32.7–86.3) (14.2–39.8) (38.6–76.0)

CI, confidence interval; NA, not applicable.

a June 2007–May 2008.

b June 2008–May 2009.

c Adjusted for the number of hospitalized patients meeting case definitions who did not have swabs tested. Adjustment was made separately for each age group, health facility and influenza season.