Characteristics of studies included in the meta-analysis
| Authors (year) | Jackson et al (2002) | Hung et al (2010) | Tseng et al (2010) | Eurich et al (2012) | Vila-Corcoles et al (2014) Ochoa-Gondar et al (2014) | Meyers et al (2004) | Lamontagne et al (2008) | Siriwardena et al (2010) | Siriwardena et al (2014) |
|---|---|---|---|---|---|---|---|---|---|
| Study type | Cohort | Cohort | Cohort | Cohort | Cohort | Case–control | Case–control | Case–control | Case–control |
| Location | Washington state, USA | Hong Kong | California, USA | Alberta, Canada | Tarragona, Spain | Kansas, USA | Quebec, Canada | England and Wales | England and Wales |
| Study period | August 1992—December 1996 | 03 December 2007–30 June 2008 | January 2002—December 2007 | 2000–2002 | December 2008—November 2011 | November 2001—March 2002 | January 1997—December 2003 | November 2001—May 2007 | September 2001—August 2009 |
| Intervention | PPV | PPV | PPV | PPV | PPV | ||||
| Comparator | Unvaccinated | Unvaccinated | Unvaccinated | Unvaccinated | Unvaccinated | ||||
| Follow-up time (retrospective for case–control studies) | Median 2.3 years | 45 834 person-years, maximum 1.2 years | Mean 4.7 years, Median 5.3 years | 90 days | 3 years, 76 033 person-years | Maximum 5 years | Maximum 10 years | Not specified | Not specified |
| Case | All AMI | New AMI | New AMI | New stroke/TIA | |||||
| Control | New bone fractures | Surgical admissions | Random matched 1:4 | Random matched 1:1 | |||||
| Total participants | 1378 | 36 636* | 84 170 | 6171 | 27 204 | 534 | 4995 | 78 706 | 94 022† |
| Average age (years)‡ | 64 | 75 | 58.4 | 59 | 71.7 | 69 | 58.9 | 65.6§ | 65.3§ |
| % male | 67 | 45.3 | 100 | 52.8 | 44.6 | 52.2 | 68.5 | 38.5 | 48.0 |
| Previous ischaemic events (%) | |||||||||
| Stroke | 7.3 | 3.4 | 4.75 | 0 | 6.25 (stroke or TIA) | 0 | |||
| MI | 100 | 1.2 | 7.2 | 0 | 0 | ||||
| ACS | 0 | ||||||||
| Ever smoked (%) | 13.7 | 57.4 | 36.4 | 31.3 | 59.7 | 26.2 | 53.4 | ||
| History of DM (%) | 24.4 | 12.4 | 11.3 | 21.7 | 7.1 | 10.3 | 10.5 | ||
*27 268 participants from PPV alone and unvaccinated groups used in meta-analysis. Original study included influenza vaccine as well.
†53 568 participants from stroke only cases and matched controls used in meta-analysis, as adjusted ORs were reported separately for stroke and TIA.
‡Range or SD of average age were not presented in all original publications.
§Average age not published, calculated using data available for proportions of those 40–64 years old and ≥65 years old. Average life expectancy for 2001 estimated as 80 years old using UK. National Statistics accessed via http://www.statistics.gov.uk
ACS, acute coronary syndrome; AMI, acute myocardial infarction; DM, diabetes mellitus; PPV, pneumococcal polysaccharide vaccine; TIA, transient ischaemic attack.