Background
Methods
Hospitalization data
Definitions
Statistical analysis
Periodic regression
Generalized linear model
Estimated number of influenza-attributable SARI
Results
Description of SARI hospitalizations
2012–2013 | 2013–2014 | 2014–2015 | 2015–2016 | 2016–2017 | 2017–2018 | Total | |
---|---|---|---|---|---|---|---|
Epidemic duration (in wk)a | 13 | 6 | 9 | 11 | 10 | 16 | / |
Number of SARI hospitalizations | 91 456 | 36 393 | 80 515 | 75 881 | 101 433 | 147 778 | 533,456 |
Diagnostic category | |||||||
Influenza | 14% | 14% | 24% | 21% | 28% | 31% | 24% |
Pneumonia | 68% | 70% | 60% | 64% | 57% | 56% | 61% |
Bronchitis | 17% | 16% | 16% | 14% | 15% | 13% | 15% |
Proportion of SARI hospitalizations in ≥ 75 y age-group | 53% | 49% | 55% | 46% | 60% | 51% | 53% |
Number of hospitalizations with ICU admission | 5 235 | 2 291 | 5 317 | 4 962 | 6 362 | 10 412 | 34,579 |
Proportion of hospitalizations with ICU admission | 6% | 6% | 7% | 7% | 6% | 7% | 6% |
Number of deaths | 5 745 | 2 111 | 5 220 | 4 202 | 6 773 | 8 965 | 33,016 |
Proportion of deaths | 6% | 6% | 6% | 6% | 7% | 6% | 6% |
Estimated influenza-attributable SARI hospitalization rates
Influenza epidemic (Dominant influenza viruses*) | Periodic regression | GLM | Influenza*** | ||||
---|---|---|---|---|---|---|---|
H | H/100,000 | 95% CI | H | H/100,000 | 95% CI | H/100,000 | |
2012–2013 (B-Yamagata) | 32 790 | 50.9 | [44.3–57.4] | NA | NA | NA | 21.5 |
2013–2014 (A(H1N1) et A(H3N2)) | 8 964 | 13.9 | [11.1–16.7] | 10 964 | 17.0 | [15.1–18.9] | 12.7 |
2014–2015 (A(H3N2)) | 38 519 | 59.7 | [55.4–64.1] | 44 804 | 69.5 | [66.3–72.7] | 34.8 |
2015–2016 (B-Victoria) | 24 921 | 38.7 | [34.2–43.1] | 29 430 | 45.6 | [43.7–47.6] | 27.7 |
2016–2017 (A(H3N2)) | 52 354 | 81.2 | [75.4–87.0] | 49 817 | 77.3 | [73.7–80.9] | 45.9 |
2017–2018 (A(H1N1) et B-Yamagata) | 69 610 | 108.0 | [99.9–116.0] | 70 780 | 109.8 | [106.2-113.3] | 69.0 |
Average of five epidemics**
|
38 873
|
60.3
|
NC
|
41 159
|
63.8
|
NC
|
38.0
|
Influenza-attributable SARI hospitalization estimates according to diagnostic category, age-group and region of hospitalization (periodic regression)
Number of SARI hospitalizations | Number of influenza-attributable SARI hospitalizations | Proportion of influenza-attributable SARI hospitalizations | SARI hospitalization rate (/100 000) | |
---|---|---|---|---|
Diagnostic category
| ||||
Influenza | 127 297 | 127 297 | 100 | 33 |
Pneumonia | 326 062 | 74 223 | 23 | 19 |
Bronchitis | 80 097 | 25 634 | 32 | 7 |
Age group
| ||||
< 15 y | 60 104 | 36 308 | 60 | 52 |
15–64 y | 119 746 | 56 742 | 47 | 23 |
65–74 y | 71 427 | 29 452 | 41 | 78 |
75–84 y | 122 338 | 48 043 | 39 | 200 |
≥ 85 y | 159 841 | 56 917 | 36 | 473 |
Total
| 533 456 | 227 154 | 43 | 59 |
Discussion
-
Adopt a coherent syndromic grouping logic around respiratory infections and compatible with the WHO definition of SARI (acute low respiratory infection with a history of fever or measured fever ≥ 38 °C associated with a cough, occurring within the previous 10 days and requiring hospitalization) [5].
-
Include in the definition of SARI: all influenza infections, whether coded as PD or AD (most hospitalizations with influenza as an AD were associated with a diagnosis it was reported as a complication or co-infection, and excess hospitalizations of respiratory infections (acute bronchitis and pneumonia) in order to compensate for the lack of confirmation of virological diagnosis of influenza [4, 12].