Background
Methods
Time period of the analysis
Data sets
Syndromic surveillance data
Geographical specification of the data source | |||||||
---|---|---|---|---|---|---|---|
Abbreviation of the data source | Data source | Country | Region | City/District | Population served (approx.) | Data provider | Baseline period* |
EMD-AT | Emergency Medical Dispatch | Austria | Tyrol data source covers 3 of 9 districts in Tyrol | Innsbruck city, Innsbruck district, Kufstein district | 380,000 | Dispatch Centre Tyrol | 1/2005-12/2008 |
Except cases from December to March each year. | |||||||
EP-AT | Emergency Physician service (ambulances) | Austria | Tyrol | Kufstein district | 99,000 | Dispatch Centre Tyrol | 1/2006-12/2008 |
Except cases from November to March each year. | |||||||
EP-BE | Emergency Physician service (ambulances) | Belgium | 10,500,000 | Ministry of Health, Belgium | 3/2009-8/2009 | ||
ED-BE | Emergency Department | Belgium | Flemish Brabant | Leuven | a. 91,000 (Leuven) b. 1,000,000 (reference hospital for the region Flemish Brabant) | University Hospital Leuven | 3/2009-8/2009 |
ED-ES | Emergency Department | Spain | Autonomous Region Cantabria | Santander | a. 300,000 (Santander) b. 580,000 (reference hospital for the Autonomous Region Cantabria) | University Hospital Marqués de Valdecilla | 8/7/2009-30/8/2009 |
Reference data
Influenza pandemic according to reference data in 2009 | |||||||
---|---|---|---|---|---|---|---|
Reference data for… | Reference data source | Geographical level | Reporting delay* | Start week | Peak week | Duration (weeks) | Duration (days) |
EMD-AT†, EP-AT†
| Information on sick leave due to acute respiratory infections from a major Tyrolean health insurance. | regional | information for week x available on week x + 1 | 44 | 47 | 9 | 67$
|
(Tyrol, Austria) | |||||||
EP-BE, | Notified influenza cases of the sentinel general practitioner system. | national | information for week x available on week x + 3 | 40 | 44 | 10 | 70 |
ED-BE | (Belgium) | ||||||
ED-ES | Notified influenza cases of the sentinel general practitioner system. | regional | information for week x available on week x + 3 | 41 (period 1) | 43 | 8 | 56 |
(Autonomous Region Cantabria, Spain) | 49 (period 2) |
Variables
Data source | Syndrome | Health information codes | Code distribution 2009 | ||
---|---|---|---|---|---|
EMD-AT | respiratory syndrome | AMPDS v12.0 | Boolean operator : OR | N | % |
6C1 | Breathing problems - Abnormal breathing | 465 | 26.9 | ||
6C1A | Breathing problems - abnormal breathing + asthma | 71 | 4.1 | ||
6D1 | Breathing problems - Not alerting | 750 | 43.3 | ||
6D1A | Breathing problems - not alerting + asthma | 230 | 13.3 | ||
6D2 | Breathing problems - Difficulty in speaking between breaths | 22 | 1.3 | ||
6D2A | Breathing problems - difficulty in speaking between breaths + asthma | 4 | 0.2 | ||
6D3 | Breathing problems - changing colour | 154 | 8.9 | ||
6D3A | Breathing problems - changing colour + asthma | 31 | 1.8 | ||
6D4 | Breathing problems - clammy | - | - | ||
6D4A | Breathing problems - clammy + asthma | - | - | ||
26A4 | Sick person - Fever/chills | 4 | 0.2 | ||
26O26 | Sick person - Sore throat (without difficulty breathing or swallowing) | - | - | ||
Total
|
1731
|
100.0
| |||
EP-AT
| ILI* | ICD-10 | Boolean operator : OR | ||
J00 | Acute nasopharyngitis [common cold] | 1 | 1.6 | ||
J02 | Acute pharyngitis (includes sore throat) | - | - | ||
J04 | Acute laryngitis and tracheitis | 3 | 4.7 | ||
J06 | Acute upper respiratory infections of multiple and unspecified sites | 8 | 12.5 | ||
J09 | Avian Influenza | - | - | ||
J10 | Influenza due to other identified influenza virus | 1 | 1.6 | ||
J11 | Influenza, virus not identified | 8 | 12.5 | ||
J16 | Pneumonia due to other infectious organisms, not elsewhere classified | 3 | 4.7 | ||
J18 | Pneumonia, organism unspecified | 28 | 43.8 | ||
R05 | Cough | 3 | 4.7 | ||
R50 | Fever of other and unknown origin | 9 | 14.1 | ||
Total
|
64
|
100.0
| |||
EP-BE
| ILI* | ICD-9 | Boolean operator : OR | ||
460 | Acute nasopharyngitis [common cold] | 22 | 1.2 | ||
462 | Pharyngitis, acute | - | - | ||
464 | Acute laryngitis and tracheitis | - | - | ||
464.0 | Acute laryngitis | - | - | ||
464.1 | Acute tracheitis | - | - | ||
464.2 | Acute laryngotracheitis | - | - | ||
465 | Acute upper respiratory infections of multiple or unspecified sites | - | - | ||
465.0 | Acute laryngopharyngitis | - | - | ||
465.8 | Acute upper respiratory infections of other multiple sites | - | - | ||
465.9 | Acute upper respiratory infections of unspecified site | - | - | ||
480.9 | Viral pneumonia unspecified | 56 | 3.0 | ||
488 | Influenza due to certain identified influenza viruses | - | - | ||
488.0 | Influenza due to identified avian influenza virus | - | - | ||
488.1 | Influenza due to identified novel h1n1 influenza virus | - | - | ||
487 | Influenza | - | - | ||
487.0 | Influenza with pneumonia | - | - | ||
487.1 | Influenza with other respiratory manifestations | - | - | ||
487.8 | Influenza with other manifestations | 109 | 5.9 | ||
486 | Pneumonia organism unspecified | 986 | 53.2 | ||
786.2 | Cough | 63 | 3.4 | ||
780.6 | Fever and other physiologic disturbances of temperature regulation | 618 | 33.3 | ||
Total
|
1854
|
100.0
| |||
ED-BE
| ILI* | chief complaint or working diagnosis, Boolean operator : OR | |||
free text including | cough, muscle pain, flu, H1N1, sore throat, influenza, fever | na†
| na†
| ||
Total
|
5681
|
100.0
| |||
ED-ES
| ILI* | case definition, Boolean operator : AND | |||
i) the appearance of sudden symptoms and at least one of the four general symptoms (fever or slight fever (feverishness), headache, muscle pain, general malaise), and (ii) at least one of the three respiratory symptoms (cough, sore throat, difficulty breathing), as well as (iii) the absence of other diagnostic suspicion. | 1127 | 100.0 | |||
Total
$
|
1127
|
100.0
|
Statistical analysis
Characteristics of syndromic surveillance data
Aberration detection
EMD-AT | EP-AT | EP-BE | ED-BE | ED-ES | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Respiratory syndrome | ILI | ILI | ILI | ILI | ||||||
Period | Baseline*
| Test†
| Baseline*
| Test†
| Baseline*
| Test†
| Baseline*
| Test†
| Baseline*
| Test†
|
Mean daily count
| 4.7 | 4.8 | 0.07 | 0.2 | 4.2 | 5.0 | 13.6 | 17.9 | 4.1 | 7.3 |
Standard deviation | 2.2 | 2.1 | 0.3 | 0.5 | 2.1 | 2.5 | 4.0 | 6.0 | 3.0 | 8.0 |
95% Confidence Interval | 4.6-4.9 | 4.4-5.5 | 0.05-0.09 | 0.2-0.3 | 3.9-4.5 | 4.5-5.4 | 13.0-14.2 | 16.8-19.0 | 3.3-4.9 | 5.9-8.7 |
Median daily count
| 5 | 5 | 0 | 0 | 4 | 5 | 13 | 18 | 3 | 5 |
Minimum daily count
| 0 | 1 | 0 | 0 | 0 | 1 | 5 | 5 | 0 | 0 |
Maximum daily count
| 15 | 12 | 2 | 2 | 10 | 14 | 27 | 34 | 15 | 36 |
Day-of-the-week effect
| yes | no | no | no | yes | |||||
evaluated by Kruskal-Wallis test | p = 0.007 | p = 0.43 | p = 0.70 | p = 0.19 | p = 0.04 | |||||
Mean daily count
| ||||||||||
Monday | 4.7 | 0.08 | 4.1 | 14.6 | 2.7 | |||||
Tuesday | 4.4 | 0.08 | 4.0 | 12.3 | 4.9 | |||||
Wednesday | 4.4 | 0.03 | 3.9 | 12.5 | 5.5 | |||||
Thursday | 5.0 | 0.08 | 3.6 | 13.7 | 4.8 | |||||
Friday | 4.5 | 0.12 | 4.8 | 14.6 | 3.4 | |||||
Saturday | 4.7 | 0.08 | 4.3 | 13.2 | 5.5 | |||||
Sunday | 5.4 | 0.05 | 4.6 | 14.4 | 2.0 | |||||
Poisson CUSUM calibration
$
| ||||||||||
no day-of-the-week variation | mean = 0.07 | mean = 4.2 | mean = 13.6 | |||||||
k = 1 | k = 5 | k =14 | ||||||||
S0 = 1 | S0 = 4 | S0 = 10 | ||||||||
h = 2 | h = 7 | h = 20 | ||||||||
day-of-the-week variation | ||||||||||
stratum 1 |
Sunday
|
Sunday, Monday
| ||||||||
mean = 5.4 | mean = 2.3 | |||||||||
k = 6 | ||||||||||
S0 = 5 | k = 3 | |||||||||
h = 10 | S0 = 3 | |||||||||
h = 5 | ||||||||||
stratum 2 |
Monday-Saturday
|
Tuesday-Saturday
| ||||||||
mean = 4.6 | mean = 4.8 | |||||||||
k = 5 | k = 5 | |||||||||
S0 = 4 | S0 = 4 | |||||||||
h = 7 | h = 7 |
Timeliness
Validity assessment based on aberration detection
Software
Results
Timeliness assessment
Data source | Peak comparison | Cross-correlation function | First aberration detected by Poisson CUSUM | |
---|---|---|---|---|
(weeks) | (weeks) | (days) | ||
Without reporting delay+
| With reporting delay+
| |||
EMD-AT | na* | not significant | 0 | -6 |
EP-AT | na* | not significant | na* | na* |
EP-BE | -1 | -1 | +10 | +2 |
0.60 | ||||
ED-BE | -1 | not significant | 0 | -8 |
ED-ES | +1 | +1 | +19 (period 1) | +11 (period 1) |
0.89 | 0 (period 2) | -8 (period 2) |
Validity assessment
Data source | Sensitivity*% | Specificity†% | Sensitivity*% | Specificity†% | False detection rate‡% | |
---|---|---|---|---|---|---|
Weekly | Daily | Weekly | Daily | |||
EMD-AT | (3/9) | (5/8) | (5/67) | (53/56) | (3/6) | (3/8) |
33.3
|
62.5
|
7.5
|
94.6
|
50.0
|
37.5
| |
EP-AT | (0/9) | (8/8) | (0/67) | (56/56) | (0/0) | (0/0) |
0.0
|
100.0
|
0.0
|
100.0
| |||
EP-BE | (6/10) | (6/7) | (12/70) | (51/53) | (1/7) | (2/14) |
60.0
|
85.7
|
17.1
|
96.2
|
14.3
|
14.3
| |
ED-BE | (10/10) | (4/7) | (26/70) | (45/53) | (3/13) | (8/34) |
100.0
|
57.1
|
37.1
|
84.9
|
23.1
|
23.5
| |
ED-ES | (6/8) | (8/9) | (30/56) | (63/67) | (1/7) | (4/34) |
75.0
|
88.9
|
53.6
|
94.0
|
14.3
|
11.8
|