Invasive haemophilus influenza disease
The major disease burden of invasive H. influenzae infection occurs in children under five years (Fogarty, 1995). The most harmful complication is bacteraemia, which is accompanied by a focal infection such as meningitis, pneumonia, or cellulitis in 3050% of cases (Devarajan, 2009).
Risk of complications
Meningitis is the principal clinical presentation of invasive disease, but bone and joint infections, pneumonia, epiglottitis, cellulitis and septicaemia can also occur. Skin and soft tissue infections may occur in around 6% of patients, followed by a limited number of sequelae (Otero Reigada, 2005). Only the invasive forms are considered as health states in the model.
To estimate the risk of meningitis we used the surveillance data reported in the ECDC Invasive Disease Surveillance report on clinical presentations of the acute symptomatic disease (ECDC, 2013a; ECDC, 2013b). Reported data indicates that meningitis and septicaemia occur together in 01% of cases, whereas meningitis alone occurs in 1518% (15% in 2010, 18% in 2011) of cases, resulting in an overall risk of 1518% of developing meningitis. The risk of developing meningitis during the acute phase of the disease is age-specific. Age and gender-specific data were extracted from ECDCs TESSy database on the meningitis complications of IHID for 2010 and 2011 (see Table 4). The risk of developing the long-term sequelae is age and gender-specific.
Long-term sequelae
Bacterial meningitis may cause long-term sequelae and permanent disabilities. To investigate this we extracted the risk of developing these complications after meningitis episodes from Edmond et al. (Edmond, 2010).
Meningitis accounts for various long-term sequelae (each of which is multiplied by the risk of developing meningitis during the acute phase of the disease: 1518%): cognitive difficulties (0.170.20%), seizure disorders (0.230.27%), hearing loss (0.480.58%), motor deficit (0.330.40%), visual disturbance (0.080.09%), behavioural problems (0.320.38%), clinical impairments (0.180.22%) and multiple impairments (0.390.47%) (Edmond, 2010).
Case fatality proportion
The parameters for the case fatality proportion were based on data for EU/EEA countries in 2011, see Table 3 (ECDC, 2013).
Model input summary
Table 1. Transition probabilities used in the outcome tree
Health outcome |
Distribution of health states in health outcome |
Transition probability |
Source/assumption |
Hearing loss |
|
0.48-0.58% |
Edmond, 2010 |
Cognitive difficulties |
|
0.17-0.20% |
Edmond, 2010 |
Seizure disorder |
|
0.23-0.27% |
Edmond, 2010 |
Motor deficit |
|
0.33-0.40% |
Edmond, 2010 |
Visual disturbance |
|
0.08-0.09% |
Edmond, 2010 |
Behavioural problems |
|
0.32-0.38% |
Edmond, 2010 |
Clinical impairments |
|
0.18-0.22% |
Edmond, 2010 |
Multiple impairments |
|
0.39-0.47% |
Edmond, 2010 |
Fatal cases due to symptomatic infection |
|
See Table 3 (5.4-19.5%) |
ECDC, 2013 |
Table 2. Disability weights and duration
Health
outcome |
Disability Weight (DW) (Haagsma, 2015) |
Duration |
||
DW |
Label |
In years |
Source |
|
Symptomatic infection |
0.655 (0.579-0.727) |
Intensive care unit admission |
0.019 |
Tunkel, 2004 Assuming the duration of antimicrobial therapy |
Permanent disability following meningitis |
|
|
Remaining life expectancy |
|
1. Hearing loss |
0.008-0.103 |
From lowest to highest hearing loss related DWs |
|
|
2. Cognitive difficulties |
0.044-0.188 |
From lowest to highest intellectual disability related DWs |
|
|
3. Seizure disorder |
0.07 (0.057-0.088) |
Generic uncomplicated disease: worry and daily medication |
|
|
4. Motor deficit |
0.011-0.421 |
From lowest to highest motor impairment related DWs |
|
|
5. Visual disturbance |
0.004-0.171 |
From lowest to highest vision impairment related DWs |
|
|
6. Behavioural problems |
0.088 (0.07-0.108) |
Subacute sclerosing panencephalitis phase 1 (assuming best fitting health state description) |
|
|
7. Clinical impairments |
0.004-0.421 |
From lowest to highest DW included in this model |
|
|
8. Multiple impairments |
0.004-0.421 |
From lowest to highest DW included in this model |
|
|
Table 3. CFR following symptomatic infection
Age |
CFR |
0 |
19.5% |
1-4 |
6.5% |
5-14 |
5.7% |
15-64 |
5.4% |
≥65 |
15% |
Table 4. Age specific distribution per gender of the 15-18% risk of developing meningitis manifestation during the symptomatic infection (TESSy 2010-2011)
Age |
% |
|
F |
M |
|
0 |
15.69 |
17.12 |
01-04 |
15.69 |
18.49 |
05-09 |
2.61 |
5.48 |
10-14 |
1.31 |
2.74 |
15-19 |
1.31 |
2.74 |
20-24 |
2.61 |
4.11 |
25-29 |
0.00 |
0.00 |
30-34 |
3.27 |
1.37 |
35-39 |
1.96 |
4.79 |
40-44 |
3.92 |
7.53 |
45-49 |
3.92 |
8.22 |
50-54 |
7.19 |
2.74 |
55-59 |
7.19 |
2.74 |
60-64 |
3.27 |
4.79 |
65-69 |
10.46 |
3.42 |
70-74 |
11.11 |
5.48 |
75-79 |
5.23 |
4.11 |
80-84 |
2.61 |
1.37 |
85+ |
0.65 |
2.74 |
Total |
100 |
100 |
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