Table 2 Baseline characteristics of included studies
Author, year | Country | Study design | Influenza season(s) | Age-group (yrs) or risk group | Age (yrs), range or mean (± SD) | % male | Data sources | Identification of outcomes | Study size (n) |
|---|---|---|---|---|---|---|---|---|---|
Bond et al., 2012 [17] | US | Cohort | 2005/06 | Patients with ESRD | V, 60.6 (15.2) | V, 52.5 | 3 ESRD Networks, records of the US Renal Database (USRDS) | All-cause death through ESRD death notification form | 20,220 (without pneumococcal vaccine) |
UV, 57.9 (15.9) | UV, 50.8 | ||||||||
Campitelli et al., 2010 [7] | Canada | Cohort | 8 seasons between 1996 and 2007 | Elderly ≥ 65 | V, 75.3 (6.6) | V, 40.8 | National health surveys data linked to Ontario Health Insurance (OHIP) and Discharge Abstract (CIHI) databases | Registered persons database and ICD-9/-10 admission codes | V, 14,512 |
UV, 74.2 (6.7) | UV, 40.7 | UV, 11,410 | |||||||
Foster et al., 1992 [18] | US | Case–control (matched) | 1989/90 | Elderly ≥ 65 | V, 65-94+ | V, 50.8 | Databases of participating hospitals | Hospital discharge ICD-9 codes | Cases, 721 |
UV, 65-94+ | UV, 47.3 | Controls, 1786 | |||||||
France et al., 2006 [34] | US | Cohort | 1995/96-2000/01 | Women and their newborns | V, 30.8 (5.5) | NA | Health maintenance organization (Kaiser Permanante and Group Health Cooperative) | ICD-9 codes for medically attended acute respiratory illnesses in infants | V, 3160 |
UV, 29.7 (5.5) | UV, 37,969 | ||||||||
Groenwold et al., 2009 [19] | Netherlands | Cohort | 1995/96-2002/2003 | Elderly ≥ 65 | V, 75 (median) | V, 39.4 | GPRD of University Medical Center Utrecht | ICPC coding system | V, 37,501 |
UV, 74 (median) | UV, 35.2 | UV, 13,405 | |||||||
Hottes et al., 2011 [20] | Canada | Cohort | 2000/01-2005/06 | Elderly ≥ 65 | V, 75 (median) | V, 43 | Manitoba Immunization Monitoring System (MIMS) and Manitoba health policy database | All-cause mortality or hospital admission ICD-9/-10 codes | 139,185 (00/01) to 140,735 (05/06) |
UV, 73 (median) | UV, 44 | ||||||||
Jackson et al., 2006 [35] | US | Cohort | 1995/96-2002/3 | Elderly ≥ 65 | V, 51 % >74 | V, 42.7 | Health maintenance organization (Group Health Cooperative) | All-cause mortality or hospital ICD-9 discharge codes | 72,527 |
UV, 46 % >74 | UV, 41.9 | ||||||||
Jackson et al., 2002 [21] | US | Cohort | 1992-1996 | Patients with nonfatal MI | All subjects, 64 (median) | among ≥ 65: | Health maintenance organization (Group Health Cooperative) | Hospital discharge ICD-9 codes, confirmed by chart review | V, 1016 |
UV, 362 | |||||||||
V, 47 | |||||||||
UV, 59 | |||||||||
Jackson et al., 2008 [5] | US | Case–control (matched) | 2000/1-2001/2 | Elderly 65-94 | Cases, 62 % >74 | cases, 51 | Health maintenance organization (Group Health Cooperative) | ICD-9 code for CA pneumonia and validation using hospital records | Cases, 1173 Controls, 2346 (1838 V, 508 UV) |
Johnstone et al., 2012 [33] | 40 countries | Cohort | 2003/04-2006/7 | Elderly ≥ 65 with VD or diabetes | Mean (4 seasons) | Range (4 seasons) | Clinical databases from two RCTs (ONTARGET- and TRANSCEND-trial) | Outcomes adjudicated by independent committee using clinical data | 31,546 |
V, 67-68 | V, 72-73 | ||||||||
UV, 65-66 | UV, 67-70 | ||||||||
Liu et al., 2012 [22] | Taiwan | Cohort | 2002-2006 | Elderly > 65 with heart disease | V, 74.8 (6.3) | V, 58.3 | National Health Research Institute-released cohort dataset | ICD-9 codes for heart diseases | V, 2760 |
UV, 75.7 (7.0) | UV, 51.8 | UV, 2288 | |||||||
Mangtani et al., 2004 [16] | UK | Cohort | 1989/90-1998/99 | Elderly ≥ 65 | Not reported | Not reported | General practice research database (GPRD) | ICD-9 codes for acute respiratory illnesses; all respiratory-related deaths | Person-years: influenza season, 419,748 summer, 692,415 |
McGrath et al., 2012 [23] | US | Cohort | 1997-1999 and 2001 | Patients with ESRD | Mean (4 seasons) | Range (4 seasons) | Medicare claims from the US Renal Data System (USRDS) | All-cause death through ICD-9 codes; Medicare claims from the USRDS | 107,465 (1997) to 126,699 (2001) |
V, 62.3-63.9 | V, 52.2-53 | ||||||||
UV, 60.3-61.7 | UV, 50.4-51.6 | ||||||||
Nicol et al., 2008 [24] | US | Cohort | 2002/03-2005/06 | Adults (students) | V, 25.2 (7.9) | V, 25.5 | Internet-based survey | Self-reported occurrences of ILI and health care use | 12,795 |
UV, 23.3 (6.3) | UV, 29.4 | ||||||||
Nicol et al., 2009 [25] | US | Cohort | 2006/07 | Adults, 50-64 | Not reported | V, 24 | Internet-based survey | Self-reported occurrences of ILI and health care use | 479 |
UV, 16 | |||||||||
Ohmit et al., 1995 [26] | US | Case–control (matched) | 1990/91-1991/92 | Elderly ≥ 65 | not reported | not reported | Admission and discharge data of 21 participating hospitals | ICD-9 hospitalization code for pneumonia/influenza | Cases, 1557 Controls, 3401 |
Omer et al., 2011 [27] | US | Cohort | 2004/05-2005/06 | Women and their newborns | V, 18.3 % < 19 | NA | Georgia Pregnancy Risk Assessment Monitoring System (PRAMS) | PRAMS database (questionnaire or interview) | V, 578 |
UV, 3590 | |||||||||
UV, 14.5 % < 19 | |||||||||
Örtqvist et al., 2007 [15] | Sweden | Cohort | 1998/99-2000/01 | Elderly ≥ 65 | V, 51 % >74 | V, 41.3 | Population register (via national identification number) | ICD-9/-10 codes and cause of death register | 260,155 |
UV, 51 % >74 | UV, 39.0 | ||||||||
Schembri et al., 2009 [28] | UK | Cohort | 1998-2006 | Adults > 40 with COPD | V, 27 % > 69 | V: 42.8 | The Health Improvement Network database (THIN), covering data of general practices | Diesease classification codes of THIN databases (“Read codes”) | V, 9679 |
UV, 31,062 | |||||||||
UV, 12 % > 69 | UV: 42.8 | ||||||||
Sung et al., 2014 [29] | Taiwan | Cohort | 2000-2007 | Elderly ≥ 55 with COPD | V, 20 % >74 | V: 58.7 | Reimbursement claims from National Health Insurance Research Database (NHIRD) | ICD-9 codes for acute MI or angina pectoris with invasive therapy | V, 3027 |
UV, 17 % >74 | UV: 60.8 | UV, 4695 | |||||||
Tessmer et al., 2011 [30] | Germany | Cohort | 2002-2006 | Adults with pneumonia (CAP) | V, 67.6 (14.5) *1 | V: 57.2 | National Community Acquired Pneumonia Competence Network (CAPNET) | CAPNET database entries | V, 1721 |
UV, 3279 | |||||||||
UV, 55.7 (19.0) | UV: 52.5 | ||||||||
Vila-Córcoles et al., 2007 [31] | Spain | Cohort | 2002-2005 | Elderly ≥ 65 | V, 51 % > 74 | V, 44.3 | Databases of Primary Health Care Centres (PHCC) | ICD-9 codes of PHCC and Civil Registry Offices | V, 6051 |
UV, 5189 | |||||||||
UV, 38 % > 74 | UV, 43.6 | ||||||||
Wong et al., 2012 [32] | Canada | Cohort | 2000/01-2008/09 | Elderly ≥ 65 | V, 75.5 (6.6) | V, 43.8 | Ontario Health administrative databases | ICD-9/ -10 codes of databases and registered persons database | 1,297,051 (00/01) to 1,527,364 (08/09) |
UV, 74.5 (6.8) | UV, 43.6 |