Table 4.
Summary of differences between participants and non-participants by study
| Study | Personal characteristics | |||||
|---|---|---|---|---|---|---|
| Age | Sex | Race | Income | Education | Health status | |
| Al-Shahi 2005w2 | NS | NS | NR | NS | NR | Less disability (Rankin score); P<0.001 |
| Bryant 2006w4 | Varied by age strata; P<0.001 | More females: odds ratio 2.21 (95% CI 1.77 to 2.75) | NR | NR | NR | NR |
| Buckley 2007w5 | NS | Fewer females: odds ratio 0.73 (95% CI 0.54 to 0.97) | NR | NS | NR | NR |
| Dunn 2004w7 | Varied by age strata; P<0.001 | More females: odds ratio 1.07 (95% CI 1.03 to 1.12) | NR | NR | NR | NR |
| Edlund 1985w8 | NS | NR | NR | NR | NR | NR |
| Harris 2004w10 | NS | NS | NS | NS | NR | More disability (disability score); P<0.001 |
| Huang 2007w11 | Varied by age strata; P<0.001 | Fewer females: odds ratio 0.90 (95% CI 0.81 to 1.0) | Varied by race strata; P<0.001 | Varied by income strata; P<0.001 | Varied by education strata; P<0.001 | Varied by SF-36 subscale |
| Jacobsen 1999w12 | Varied by age strata; P<0.001 | NS | NR | NR | NR | More comorbidity (Charlson index =2); P=0.008 |
| Klassen 2005; healthyw13 | NS | NS | NR | Varied by income strata | NS | NR |
| Klassen 2005; NICUw13 | NS | NS | NR | NS | NS | NR |
| Matsui; genetic 2005w15 | NR | NS | NR | NR | NR | NR |
| Matsui; non-genetic 2005w15 | NR | Fewer females: odds ratio 0.62 (95% CI 0.46 to 0.82) | NR | NR | NR | NR |
| McKinney 2005w16 | NS | NS | NS | NS | NR | Varied by paediatric risk of mortality score; P=0.024 |
| Schwartz 2005w19 and Phipps 2004w18 (race) | Younger: 58.7 (20.2) v 67.7 (18.6) | Fewer females: odds ratio 0.67 (95% CI 0.49 to 0.91) | NS | NR | Varied by education strata; P=0.019 | NR |
| Tate 2006w20 | Varied by age strata | NR | Varied by race strata | Varied by income strata | Varied by education strata | NR |
| Tu 2004; phase Iw1 | Younger; 69 v 72, P<0.001 | NS | Varied by race strata; P<0.001 | NR | NR | NR |
| Tu 2004; phase IIw1 | NS | Fewer females: odds ratio 0.79 (95% CI 0.68 to 0.91) | Varied by race strata; P<0.001 | NR | NR | NR |
| Woolf 2000w21 | NS | Fewer females: odds ratio 0.59 (95% CI 0.42 to 0.81) | Fewer black patients; P=0.013 | NS | NS | More physical disability; weighted mean difference -2.5 (95% CI -3.98 to -1.02) |
| Yawn 1998w23 | Varied by age strata; P=0.018 | NS | NR | NR | NR | NR |
| Young 2001w24 | Varied by age strata; P<0.001 | NR | NR | NR | More education beyond school level; P<0.001 | NR |
NR=not reported; NS=no statistically significant difference between participants and non-participants. See web extra appendix B for detailed information on each characteristic.