Background
Methods
Eligibility criteria
Search strategy and data extraction
Assessment of bias
Assessment of quality of the body of evidence
Statistical analysis
Results
Selection of studies
Study characteristics
Author
|
Study design, year
|
Country
|
Age in years (mean or range)
|
Percentage male
|
Identification of diabetic patients
|
Predominantly circulating influenza (sub)strains
|
Study size (n)
|
---|---|---|---|---|---|---|---|
Cohort studies
| |||||||
Hak [29] | Prospective, 1996/1997 and 1997/1998 | US | ≥65, but not reported for diabetic sub-cohort | Not reported for diabetic sub-cohort | ICD-9 codes, database of managed care organizations | A(H3N2) in both seasons | 14,915 in 96/97 |
21,991 in 97/98 | |||||||
Heymann [21] | Retrospective, 2000/2001 | Israel | Vacc., 72.8 ± 0.6 | Vacc., 51.8 | ICD-9 codes, diabetes register of healthcare service | Not reported | 16,383 |
Non-vacc., 73.1 ± 0.5 | Non-vacc., 42.1 | ||||||
Isotani [31] | Retrospective, 1999/2000 | Japan | Not reported | Not reported | Outpatient clinic, unclear | Influenza A | 450 |
Rodriguez-Blanco [32] | Retrospective, 2002–2005 | Spain | Vacc., 75.2 ± 6.5 | Vacc., 39.8 | ICD-9 codes, clinical records | A(H3N2) | 2,650 |
Non-vacc., 73.1 ± 6.9 | Non-vacc., 42.2 | ||||||
Selvais [33] | Prospective, 1995/96 | Belgium | 56.3 ± 15.9 years | 55 | Diabetes clinic, unclear | Not reported | 432 |
Schade [34] | Retrospective, 1995–1997 | US | 65 to 114 years | Not reported | ICD-9 codes, hospital discharge | Not reported | 26,443 in 96/97 |
23,839 in 97/98 | |||||||
Case–control studies
| |||||||
Colquhoun [36] | not matched, 1989 and 1993 | UK | ≤19–85 years | Cases, n = 59 | ICD-9 codes, diabetes register | 1989, A(H3N2) | 114 (37 cases, 77 controls) |
Controls, n = 55 | 1993, A(H3N2) and B | ||||||
Gasparini [37] | Matched, 2010/11 | Italy | Not reported for diabetic sub-cohort | Not reported for diabetic sub-cohort | ICD-9 codes, hospital discharge | A(H1N1)pdm, and B | 78 (46 cases, 32 controls) |
Lau2 [35] | Nested, 2000–2008 | Canada | Working-age, 53 | Working age, 52 elderly, 47 | ICD-9/10 codes, administrative database | Not reported | 91,605 |
Elderly, 741 | |||||||
Looijmans [38] | Nested, 1999/2000 | Netherlands | Cases, 68.1 ± 13.7 | Cases, 51.6 controls, 38.3 | ICPC codes, general practitioners | A(H3N2) | 1,753 (192 cases, 1,561 controls) |
Controls, 69.8 ± 12.6 | |||||||
Wang [39] | Nested, 2001–2009 | Taiwan | Vacc., 73.1 ± 5.9 | Vacc, 50.0 | ICD-9 codes, NHRI-database | Not reported | 9,025 (4,571 vacc., 4,454 non-vacc.) |
Non-vacc., 73.2 ± 6.8 | Non-vacc., 49.5 | ||||||
Total population
|
170,924
3
|
Reported outcomes
Risk of bias assessment in individual studies
Vaccine effectiveness in adults aged 18 to 64 years
Age-group (years)
|
Outcome/Design
|
No of studies included
|
Crude OR (95% CI)
|
I
2
|
No of studies included
|
Adjusted OR (95% CI)
|
I
2
|
No of studies included
|
Off-season adjusted OR (95% CI)
|
I
2
| |
---|---|---|---|---|---|---|---|---|---|---|---|
0–17
|
No studies
| 0 | – | – | 0 | – | – | 0 | – | – | |
18–64
|
All-cause mortality
| ||||||||||
Case–control studies | 1 | 0.46 (0.11–1.89) | NA1 | 1 | 0.76 (0.07–8.06) | NA1 | 0 | – | NA1 | ||
All-cause hospitalization
| |||||||||||
Case–control studies | 2 | 0.32 (0.19–0.54) | 0% | 3 | 0.42 (0.19–0.94) | 77% | 1 | 0.73 (0.65–0.83) | NA1 | ||
Influenza/pneumonia hospitalization
| |||||||||||
Case–control studies | 0 | – | – | 1 | 0.57 (0.46–0.72) | NA1 | 1 | 0.88 (0.68–1.14) | NA1 | ||
Influenza-like illness
| |||||||||||
Cohort studies | 1 | 0.76 (0.50–1.15) | NA1 | 0 | – | – | 0 | – | – | ||
Case–control studies | 0 | – | – | 1 | 0.99 (0.97–1.01) | NA1 | 1 | 1.00 (0.90–1.12) | NA1 | ||
≥65
|
All-cause mortality
| ||||||||||
Cohort studies | 3 | 0.54 (0.37–0.79) | 90% | 2 | 0.62 (0.57–0.68) | 0% | 1 | 0.70 (0.37–1.31) | NA1 | ||
Case–control studies | 2 | 0.39 (0.35–0.43) | 0% | 2 | 0.44 (0.36–0.53) | 0% | 0 | – | – | ||
All-cause hospitalization
| |||||||||||
Cohort studies | 1 | 0.83 (0.72–0.95) | NA1 | 0 | – | – | 1 | 0.91 (0.71–1.17) | NA1 | ||
Case–control studies | 2 | 0.89 (0.81–0.98) | 0% | 3 | 0.77 (0.60–0.99) | 94% | 1 | 0.66 (0.59–0.74) | NA1 | ||
Influenza/pneumonia hospitalization
| |||||||||||
Case–control studies | 1 | 0.20 (0.07–0.61) | NA1 | 1 | 0.55 (0.47–0.66) | NA1 | 1 | 0.48 (0.32–0.70) | NA1 | ||
Influenza-like illness
| |||||||||||
Case–control studies | 0 | – | – | 1 | 0.87 (0.84–0.90) | NA1 | 1 | 0.82 (0.70–0.96) | NA1 | ||
Not reported
|
Influenza/pneumonia hospitalization
| ||||||||||
Cohort studies | 1 | 1.75 (0.10–32.68) | NA1 | 0 | – | – | 0 | – | – | ||
Influenza-like illness
| |||||||||||
Cohort studies | 1 | 0.34 (0.02–5.85) | NA1 | 0 | – | – | 0 | – | – |