Table 6: RSV hospitalization rates within published registries based on specific subpopulations compared to published randomized clinical trials.

AuthorSpecific subpopulation *RI hospitalization rate
RSV hospitalization rate
Length of hospital stay in daysRCTComments

Parnes et al. [28]
Winterstein et al. [30]
Paes et al. [31]
Cystic fibrosis0.0% ( ) [28]; *26.2 and 3.9/1000 season months [30]; *3.4% and 1.14% ( ) [31] Undefined [30, 31, 42]At 6 months follow up RSVH (1.08% [1/92 PB]) [42]Incomplete RCT [42]-PB ( );
placebo ( )

Parnes et al. [28]
Mitchell et al. [34]
Frogel et al. [37]
Romero [38]
Pedraz et al. [39]
Oh et al. [40]
Lacaze-Masmonteil et al. [41]
Chronic lung disease (CLD)5.8% ( ) [28]; *10.5% and 1.31% ( ) [34]; 2.40% ( 4,329) [37]; 4.0% ( = NS) [38]; 3.9% (  = NS) [38]; 5.5% ( , ) [39]; 3.3% ( ) [40];
*14.9% (  = 77); 9.0% (  = 400) [41]
Undefined [15, 28, 34, 3741]
Overall total days/100 children for treated (PB) patients (≤35 wk GA + CLD): 36.4 (PB) versus 62.6 (Placebo) [15]
. RSVH: 7.9% (PB) versus 12.8% (placebo)-39% reduction [15]Prevalence of CLD very high compared to other registries (81%) [41]

Parnes et al. [28]
Paes et al. [32]
Mitchell et al. [34]
Frogel et al. [37]
Romero [38]
Pedraz et al. [39]
Lacaze-Masmonteil et al. [41]
All Infants <32 wk
GA [15, 38]
Infants ≤32 wk without CLD [28, 32, 34, 37, 39, 41]
4.5% ( ) [28]; *4.7% and 1.5% ( 5,183) [32]; 1.84% ( ) [37]; *10.5% and 2.8% ( 1,056) [38]; 3.2% ( 1,446) [38]; ≤28 wk: (1.34%, 1,704) [34], 5.4% ( , ) [39]; 29–32 wk: 1.25%, ( ) [34]; 2.5% ( , ) [39]; 7.72% ( ) [41]Mean (±SD): 6.7 ± 5.4 [32]; <28 wk (6 ± 2.6) [38], 28–31 wk (14.8 ± 22.8) [38]; ≤32 wk (median 6 [IQR 4–9]) [39]
Undefined [15, 28, 34, 37, 41]
1,111. RSVH: 5.8% (PB) versus 11.0% (placebo)-47% reduction ( ) [15]IMpact trial [15]
Romero [38] reported on two US outcomes registry cohorts (1998-1999) and (1999-2000). The 2000-2001 cohort is reported by Parnes et al. [28]

Parnes et al. [28]All infants without CLD [15]2.1% ( 1,444) [28] Undefined [15, 28] . RSVH: 1.8% (PB) versus 8.1% (placebo)-78% reduction [15]IMpact trial [15]

Frogel et al. [37]
Romero [38]
Premature infants 32–35 wk GA [15, 37, 38]0.83% ( ) [37];*2.6% ( ) and 1.5% ( ) [38]; 1.3% ( ) [38]Undefined [15, 37]
Mean (±SD): 4.9 ± 3.6 [38]
. RSVH: 2.0% (PB) versus 9.8% (placebo)-80% reduction ( ) [15]IMpact trial [15]

Paes et al. [32]
Mitchell et al. [34]
Frogel et al. [37]
Premature infants 32–35 wk GA without CLD [15, 28, 37]
Infants 33–35 wk GA without CLD [32, 34]
1.6% ( ) [28]; *3.7% and 1.4% ( 1,471) [32]; 0.2% ( ) [34]; 0.83% ( 9,294) [37] Mean (±SD): 5.2 ± 5.0 [32];
Undefined [34, 37]
. RSVH: 1.8% (PB) versus 10.0% (placebo)-82% reduction [15]IMpact trial [15]

Parnes et al. [28]
Frogel et al. [37]
Infants >35 wk GA0.6% ( ) [28]; 1.13% ( ) [37] Undefined [15, 28, 37]

Mitchell et al. [34]Hemodynamically significant congenital heart disease (HSCHD) [16, 34]HSCHD: 1.99% ( ) [34]Undefined [33]
Total days/100 children: 57.4 (PB) versus 129.0 (Placebo; 56% reduction, = 0.003) [16]
: 682 (cyanotic), 605 (other). Overall RSVH: 5.3% (PB) versus 9.7% (placebo)-45% reduction. RSVH for cyanotic group: 5.6% (PB) versus 7.9% (placebo)-29% reduction ( ). RSVH for “acyanotic group”: 5.0% (PB) versus 11.8% (placebo)-58% reduction ( ) [16]Feltes et al. [16]. All patients had hemodynamically significant CHD. Study was not powered for subgroup analyses. Incidence of serious adverse events was lower in the treatment arm: 55.4% (PB) versus 63.1% (placebo; )

CHD: congenital heart disease; CLD: chronic lung disease; GA: gestational age; HSCHD: hemodynamically significant congenital heart disease; NS: not specified; PB: palivizumab; RI: respiratory related hospitalization; RSVH: respiratory syncytial related hospitalization.