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Table 1 Reviewed articles on culture-confirmed influenza in children

From: Burden of paediatric influenza in Western Europe: a systematic review

Reference

Study design

Study settings Children age

Sample

Study qualitya Study limitations/bias

Type of data

Finland

Heikkinen et al., 2004 [35]

Prospective, observational study of respiratory infections in community-based children.

Community (day care centres, family day care, and schools);

2,231 child-seasons,

1b: prospective cohort study;

Resource use, absenteeism

382 episodes of culture-confirmed influenza were documented

Only winter months were evaluated.

Study seasons: 9 October 2000 — 20 May 2001 and 1 October 2001 — 19 May 2002.

≤ 13 years.

Follow-up: not specified.

Heinonen et al., 2010 [42]

Randomised, double-blind, controlled trial comparing oseltamivir with placebo for clinical efficacy in children with influenza.

Community;

1,185 children were recruited in the community prior to influenza seasons; among those,409 children with fever or respiratory infection who attended the study clinic were randomised to either intervention or placebo; among those,98 (24.7%) children had laboratory-confirmed influenza

1b: randomised, controlled trial;

Resource use, absenteeism.

1-3 years

Not a population- based study;b

Broad exclusion criteria prior to enrolment in the trial.

Study seasons: 2 local influenza circulation seasons (14 January — 9 April 2008 and 7 January — 26 March 2009).

Follow-up: 21 days.

France

Ploin et al., 2003 [43]

Prospective, observational study in a paediatric ED of a university hospital.

Paediatric ED;

304 infants consecutively enrolled during influenza peak

2b: prospective cohort study with poor follow-up;

Resource use, absenteeism

≤ 11 months.

99 (33%) with confirmed influenza.

Not a population- based study.

Study season: 4 weeks of local influenza epidemic peak (weeks 3-6 in 2002).

Follow-up: 15 days.

Ploin et al., 2007 [36]

Prospective, observational study in a paediatric ED of a university hospital.

Paediatric ED;

575 children consecutively enrolled during influenza peak

2b: prospective cohort study with poor follow-up;

Resource use, absenteeism

< 36 months.

283 (49%) with confirmed influenza.

Not a population- based study.

Study season: 4 weeks of local influenza epidemic peak (weeks 3-6 in 2002).

Follow-up: 15 days.

Sanni et al., 2004 [44]

Prospective, observational survey of hospitalised children.

Hospital;

114 nasal swabs collected; among those – 59 (51.8%) with confirmed influenza.

1b: prospective cohort study;

Resource use.

≤ 15 years.

Not a population- based study.

Study season: 37 days of local influenza epidemic (1 January — 6 February 2002).

Follow-up: not specified.

Germany

Ehlken et al., 2005 [45]

Cost-of-illness analysis of a prospective, multi-centre, population-based epidemiological study on the impact of LRTI in children.

Office-based PCP and hospitals;

3,458 cases with LRTI, including 1,329 office based cases, 2,039 hospitalized cases, and 90 nosocomial cases.

2c: outcomes research;

Cost (direct and indirect).c

Not a population- based study;

≤ 36 months.

Limited to children with LRTI;

Costs were imputed based on existing standards.

Study period: 2 years (1 November 1999 — 31 October 2001).

Follow-up: not specified.

Italy

Bosis et al., 2005 [46]

Prospective, observational, single-centre study of children enrolled at an ED, comparing the impact of confirmed influenza and RSV with hMPV.

ED;

All children (n = 1,505) attending the ED on Wednesdays and Sundays.

1b: prospective cohort study;

Resource use, absenteeism.

< 15 years.

Not a population- based study.

Of these, 1,019 children had evidence of acute respiratory infection.

Influenza was confirmed by PCR in 230 (15.3%) of total cases; among these, 7 cases were co-infected with RSV or hMPV.

Study season: 5 months (1 November 2002 — 31 March 2003).

Follow-up: not specified.

Esposito et al., 2005 [47]

Prospective, observational, single-centre study of children admitted to an ED, comparing the impact of confirmed influenza and RSV.

ED;

1,520 children attending ED for acute conditions other than trauma on Wednesdays and Sundays;

1b: prospective cohort study;

Resource use, absenteeism

< 15 years.

Not a population- based study.

234 (15.4%) with confirmed influenza.

Study season: 5 months (1 November 2002 — 31 March 2003).

Follow-up: not specified.

Esposito et al., 2011 [37]

Prospective, observational study of children presenting to PCP with ILI

PCP

PCPs continuously followed 21,986 community children

1b: prospective cohort study with good follow-up

Resource use, absenteeism, cost (direct and indirect)

< 14 years

6,988 children with ILI presented to PCPs

Costs were imputed based on existing standards

Study season: 6 months (1 November 2008 —30 April 2009)

2,143 (30.7%) children had confirmed influenza

Follow-up: not specified

Principi et al., 2003 [48]

Prospective, observational, multi-centre study.

ED and PCP;

3,771 children with ILI; among those

1b: prospective cohort study;

Resource use, absenteeism

< 14 years.

352 (9.3%) with confirmed influenza, including 260 (8.7%) of 2,970 children seen in EDs and 92 (11.5%) of 801 children seen by PCPs

Not a population- based study.

Principi et al., 2004 [38]

Study season: 6 months (1 November 2001 — 30 April 2002).

Follow-up: not specified.

The Netherlands

Bueving et al., 2004 [49]

Randomised, double-blind, placebo-controlled trial comparing inactivated vaccine with placebo for clinical efficacy in children with asthma.

Community;

696 children with asthma enrolled through PCP offices prior to influenza seasons’ start.

1b: individual randomised, controlled trial;

HRQoL.

6-18 years.

Limited to children with asthma.

Study seasons: 2 influenza seasons (1999 — 2000 and 2000 — 2001).

Follow-up: not specified.

Van Der Zalm, et al., 2009 [50]

Prospective birth cohort study, a part of a prospective, ongoing population-based birth cohort study on determinants of wheezing illness.

Community;

305 healthy full-term infants (2-3 weeks old);

2b: individual cohort study.

Resource use.

  

≤ 1 year.

   
   

668 samples positively tested for any respiratory virus;

  
   

18 (2.7%) samples with influenza virus.

  
 

Study duration: October 2003 — September 2006.

    
 

Follow-up: until infants reached 1 year of age.

    
  1. ED = emergency department; hMPV human metapneumovirus; HRQoL = health-related quality of life; ILI = influenza-like illness; LRTI = lower respiratory tract infection; PCP = primary care paediatrician; PCR = polymerase chain reaction; RSV = respiratory syncytial virus.
  2. a Study quality according to the Oxford Centre for Evidence-based Medicine scale [41].
  3. b Studies that investigated the impact of influenza at the whole population level rather than the impact in a particular subset of patients (e.g., children admitted to hospital with fever).
  4. c Resource use, absenteeism, and HRQoL also reported but associated with ILI only (not associated with confirmed influenza).