Table 1.
Table Summary of case fatality risk studies of influenza A (H1N1-2009) included in the systematic review.
| Referencesa | Country | Study period | Death definition | Case definition | Case fatality risksb | (95% CI) |
|---|---|---|---|---|---|---|
| Estimated infections as denominatorc | ||||||
| Bandaranayake 2010a 15 | New Zealand | Apr 09 – Sep 09 | Confirmed deaths | Serology | 4.5 | na |
| Chen 2011 19 | Taiwan | Jul 09 – Aug 10 | Confirmed deaths | Serology | 1 | (0.6–1.4) |
| McVernon 2010 39 | Australia | Apr 09 – Dec 09 | Confirmed deaths | Serology | 10 | na |
| Presanis 2011a 46 | UK | Jun 09 – Aug 09 | Confirmed deaths | Deaths to hospitalizations × hospitalizations to symptomatic cases × symptomatic cases to infection | 5 | (4–8) |
| Presanis 2011c 46 | UK | Sep 09 – Feb 10 | Confirmed deaths | Deaths to hospitalizations × hospitalizations to symptomatic cases × symptomatic cases to infection | 9 | (4–14) |
| Riley 2011 48 | Hong Kong | Jul 09 – Feb 10 | Confirmed deaths | Serology | 7.6 | (6.2–9.5) |
| Steens 2011 51 | Netherlands | Sep 09 – Apr 10 | Confirmed deaths | Serology | 4.7 | (3.2–9.2) |
| Sypsa 2011b 52 | Greece | Aug 09 – Feb 10 | Confirmed deaths | ILI × LAB, adjusting for the sensitivity of LAB test and proportion of infections that are asymptomatic | 6.3 | (5.3–7.5) |
| Wong 2013a 6 | Hong Kong | May 09 – Dec 09 | Excess deaths | Serology | 8.2 | (0.1–17.3) |
| Wong 2013b 6 | Hong Kong | May 09 – Dec 09 | Confirmed deaths | Serology | 5.8 | (3.9–7.8) |
| Wu 2010 58 | Hong Kong | Apr 09 – Dec 09 | Confirmed deaths | Serology | 4.4 | (3.2–17) |
| Estimated symptomatic cases as denominatord | ||||||
| Abdalla 2011 10 | USA | Apr 09 – Apr 10 | Confirmed deaths | ILI | 20.4 | na |
| Baker 2009 13 | New Zealand | Jun 09 – Aug 09 | Confirmed deaths | ILI × LAB, adjusting for health-care seeking behaviour | 5 | (3–11) |
| Bandaranayake 2010b 15 | New Zealand | Apr 09 – Sep 09 | Confirmed deaths | Serology, scaling down to include only individuals with symptoms | 8.2 | na |
| Bandaranayake 2011 16 | New Zealand | Jan 10 – Oct 10 | Confirmed deaths | Serology, scaling down to include only individuals with symptoms | 8.5 | na |
| Brooks-Pollock 2011 17 | UK | Jul 09 – Nov 09 | Confirmed deaths | ILI × LAB, adjusting for health-care seeking behaviour | 17 | na |
| Chowell 2011a 20 | Mexico | Apr 09 – Dec 09 | ILI deaths | ILI | 1200 | (1100–1200) |
| Cutter 2010 21 | Singapore | Jun 09 – Oct 09 | Confirmed deaths | ILI of ARI cases × LAB + non-ILI of ARI cases × LAB | 6.7 | na |
| Dawood 2010 22 | Australia | Jun 09 – Aug 09 | Confirmed deaths | ILI × LAB | 9.4 | (7.1–13.2) |
| Donaldson 2009 24 | UK | Jun 09 – Nov 09 | Confirmed deaths | ILI × LAB + ANTIVIRAL service × LAB, adjusting for health-care seeking behaviour | 26 | (11–66) |
| Doshi 2012 25 | USA | Aug 09 – Sep 09 | P&I deaths | ILI | 24 | na |
| Echevarria-Zuno 2009a 26 | Mexico | Apr 09 – Jul 09 | Confirmed deaths | ILI | 100 | na |
| Flahault 2009a 27 | New Caledonia | Aug 09 | Confirmed deaths | Estimated cases, adjusting for health-care seeking behaviour | 10 | na |
| Flahault 2009b 27 | Mauritius | Aug 09 | Confirmed + suspected deaths | Estimated cases, adjusting for health-care seeking behaviour | 10 | na |
| Fraser 2009 28 | Mexico | Mar 09 – Apr 09 | Confirmed + suspected deaths | Confirmed cases among tourists, backcalculating from confirmation to infection | 440 | (370–520) |
| Godoy 2011 31 | Spain | Jun 09 – May 10 | Confirmed deaths | ILI | 30 | (10–40) |
| Hadler 2010a 34 | USA | May 09 – Jun 09 | Confirmed deaths | ILI, adjusting for background ILI using LAB and emergency department visit data | 8.6 | (6.1–15.1) |
| Hadler 2010b 34 | USA | May 09 – Jun 09 | Confirmed deaths | ILI, adjusting for background ILI using emergency department visit data | 5.4 | (4.7–6.5) |
| Kamigaki 2009 35 | Japan | Jul 09 – Dec 09 | Confirmed deaths | ILI, adjusting by medical institutions proportion | 0.7 | na |
| Kim 2011 36 | South Korea | Aug 09 – Nov 09 | Confirmed deaths | ILI × LAB, adjusting by medical institutions proportion | 16 | na |
| Larrieu 2011a 38 | Martinique | Aug 09 – Jan 10 | Confirmed deaths | ILI | 5 | na |
| Larrieu 2011b 38 | Guadeloupe | Aug 09 – Jan 10 | Confirmed deaths | ILI | 31 | na |
| Larrieu 2011c 38 | French Guiana | Aug 09 – Jan 10 | Confirmed deaths | ILI × LAB | 17 | na |
| Larrieu 2011d 38 | St. Martin | Aug 09 – Jan 10 | Flu-related deaths | ILI × LAB | 0 | na |
| Nishiura 2010g 43 | Japan | Jul 09 – Jan 10 | Confirmed deaths | ILI | 0.94 | (0.8–1.08) |
| Pebody 2010 44 | UK | Apr 09 – Mar 10 | Confirmed deaths | ILI × LAB + ANTIVIRAL service × LAB, adjusting for health-care seeking behaviour | 40 | (20–100) |
| Presanis 2009a 45 | USA | Apr 09 – Jul 09 | Confirmed deaths | Deaths to hospitalizations × hospitalizations to medically attended cases × medically attended cases to symptomatic cases + deaths to medically attended cases × medically attended cases to symptomatic cases | 48 | (26–96) |
| Presanis 2009b 45 | USA | Apr 09 – Jul 09 | Confirmed deaths | ILI | 7 | (5–9) |
| Presanis 2011b 46 | UK | Jun 09 – Aug 09 | Confirmed deaths | Deaths to hospitalizations × hospitalizations to symptomatic cases | 15 | (10–22) |
| Presanis 2011d 46 | UK | Sep 09 – Feb 10 | Confirmed deaths | Deaths to hospitalizations × hospitalizations to symptomatic cases | 25 | (13–40) |
| Renault 2011 47 | Reunion Island | Jul 09 – Oct 09 | Confirmed deaths | ARI × LAB, adjusting for health-care seeking behaviour | 7 | na |
| Sachedina 2010 49 | UK | Jun 09 – Mar 10 | Confirmed deaths | ILI × LAB + ANTIVIRAL service × LAB, adjusting for health-care seeking behaviour | 19 | (7–51) |
| Simon Mendez 2011 50 | Spain | May 09 – Mar 10 | Confirmed deaths | ILI × LAB | 43 | (38–48) |
| Sypsa 2011a 52 | Greece | Aug 09 – Feb 10 | Confirmed deaths | ILI × LAB, adjusting for the sensitivity of LAB test | 17.5 | (14.6–20.8) |
| Wilson 2009a 57 | Developed countries | Apr 09 – Jun 09 | Confirmed deaths | Confirmed cases, adjusting by a multiplier of 10–30 | 10–30 | na |
| Wilson 2009b 57 | Developed countries | Apr 09 – Jun 09 | Confirmed deaths | ILI x LAB | 2–3 | na |
| Wilson 2009c 57 | Developed countries | Apr 09 – Jun 09 | Excess deaths | 5%–10% of the US population <65y | 4–60 | na |
| Wilson 2009d 57 | Developed countries | Apr 09 – Jun 09 | Confirmed deaths | 5%–30% of the Canadian population | 0.4–3 | na |
| Laboratory-confirmed cases as denominatore | ||||||
| Adhikari 2011 11 | Nepal | Apr 09 – May 10 | Confirmed deaths | Confirmed cases | 1740 | na |
| Ahmed 2012 12 | Abu Dhabi | May 09 – Aug 09 | Confirmed deaths | Confirmed cases | 0 | na |
| Balaganesakumar 2013 14 | India | Jan 10 – Dec 10 | Confirmed deaths | Confirmed cases | 5500 | na |
| Castro-Jimenez 2009 18 | Colombia | May 09 – Jul 09 | Confirmed deaths | Confirmed cases | 3800 | na |
| Chowell 2011b 20 | Mexico | Apr 09 – Dec 09 | ILI deaths | Confirmed cases | 5000 | (4700–5300) |
| de Silva 2009 23 | Thailand | Jun 09 – Jul 09 | Confirmed deaths | Confirmed cases | 580 | na |
| Echevarria-Zuno 2009b 26 | Mexico | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases | 900 | na |
| Garske 2009a 29 | USA | Apr 09 – Jul 09 | Confirmed deaths | Confirmed + probable cases, adjusting for delay from onset to death | 680 | (590–780) |
| Garske 2009b 29 | Mexico | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 1230 | (1030–1470) |
| Garske 2009c 29 | Canada | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 430 | (300–580) |
| Garske 2009d 29 | UK | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 240 | (130–410) |
| Garske 2009e 29 | EU | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 200 | (110–320) |
| Glinsky 2009 30 | Argentina | Jul 09 | Confirmed deaths | Confirmed cases | 13500 | na |
| Gomez 2009 32 | Peru | May 09 – Sep 09 | Confirmed deaths | Confirmed cases | 1710 | na |
| Gu 2013 33 | Japan | Jul 09 – Aug 10 | Influenza-associated encephalopathy deaths | Influenza-associated encephalopathy cases | 3600 | na |
| Kool 2013 37 | Pacific Island countries | Apr 09 – Aug 10 | Confirmed deaths | Confirmed cases | 1000 | na |
| Mishra 2010 40 | India | Aug 09 – Oct 09 | Confirmed deaths, adjusting by hospitalization rate | Confirmed cases | 860 | na |
| Nishiura 2009a 41 | USA | Apr 09 – Jun 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 1230 | (210–3760) |
| Nishiura 2009b 41 | Canada | Apr 09 – Jun 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 180 | (50–410) |
| Nishiura 2010a 42 | Argentina | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 2330 | (1970–2720) |
| Nishiura 2010b 42 | Canada | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 400 | (330–470) |
| Nishiura 2010c 42 | Chile | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 250 | (180–330) |
| Nishiura 2010d 42 | Mexico | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 5580 | (5150–6020) |
| Nishiura 2010e 42 | USA | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases, adjusting for delay from onset to death | 250 | (220–290) |
| Nishiura 2010f 43 | 45 countries | Jul 09 – Jan 10 | Confirmed deaths | Confirmed cases | 690 | (650–730) |
| Tuite 2010 53 | Canada | Apr 09 – Jun 09 | Confirmed deaths | Confirmed cases | 300 | (100–500) |
| Vaillant 2009 54 | Worldwide | Apr 09 – Jul 09 | Confirmed deaths | Confirmed cases | 600 | (100–5100) |
| WHO. 2009 55 | Mexico | Apr 09 – May 09 | Confirmed deaths | Confirmed cases | 2000 | na |
| Wilking 2010 56 | Germany | Apr 09 – Mar 10 | Confirmed deaths | Confirmed + suspected cases | 110 | (100–130) |
na indicates not available; ILI, influenza-like illness consultations; LAB, laboratory specimens positive for influenza; ARI, acute respiratory infection consultations; ANTIVIRAL, antiviral dugs authorizations.
a
Letters following the year of publication (e.g., Bandaranayake 2010a) indicate one of multiple analyses, which are described in this table.
b
Case fatality risks are expressed as number of deaths per 100,000 cases or infections.
c
Overall: point estimates ranged from 1 to 10 deaths per 100,000 infections
d
Overall: point estimates ranged from 0 to 1,200 deaths per 100,000 cases
e
Overall: point estimates ranged from 0 to 13,500 deaths per 100,000 cases