Unadjusted, Adjusted (Adjusted for Traditional Risk Factors), and Fully Adjusted (Adjusted for All Listed Covariates) RRs of Ever Being Admitted to a Hospital With RSV-Related Illness Among Ontario Children <3 Years of Age: April 1, 2012, to March 31, 2019
| Characteristic . | Unadjusted, RR (95% CI) . | Adjusted,a RR (95% CI) . | Fully Adjusted,b RR (95% CI) . |
|---|---|---|---|
| Demographics (at birth) | |||
| Rural residence | 1.08 (1.01 to 1.14) | 1.03 (0.97 to 1.10) | 0.83 (0.77 to 0.89) |
| Geographic isolation | 0.68 (0.54 to 0.86) | 0.53 (0.39 to 0.72) | 0.44 (0.31 to 0.60) |
| Mother’s immigration status | |||
| Canadian born | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Long-term immigrant | 0.82 (0.78 to 0.86) | 0.73 (0.70 to 0.77) | 0.88 (0.83 to 0.93) |
| Recent immigrant | 0.61 (0.56 to 0.66) | 0.64 (0.59 to 0.70) | 0.76 (0.70 to 0.83) |
| Recent refugee | 0.94 (0.79 to 1.12) | 0.79 (0.66 to 0.94) | 0.83 (0.70 to 1.00c) |
| Maternal social vulnerabilitiesd | |||
| Child apprehended at birth | 2.00 (1.61 to 2.49) | 1.52 (1.22 to 1.89) | 0.98 (0.78 to 1.26) |
| Maternal age at birth, ye | |||
| <20 | 1.37 (1.22 to 1.53) | 1.75 (1.56 to 1.97) | 1.50 (1.33 to 1.70) |
| 20–24 | 1.32 (1.24 to 1.40) | 1.36 (1.28 to 1.45) | 1.23 (1.15 to 1.32) |
| 25–29 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 30–34 | 1.05 (1.00c to 1.10) | 0.86 (0.82 to 0.90) | 0.89 (0.85 to 0.94) |
| 35–39 | 0.96 (0.91 to 1.02) | 0.72 (0.68 to 0.77) | 0.76 (0.71 to 0.81) |
| ≥40 | 0.83 (0.74 to 0.92) | 0.56 (0.50 to 0.63) | 0.59 (0.53 to 0.67) |
| Criminal justice system involvement | 1.43 (1.23 to 1.65) | 1.33 (1.15 to 1.54) | 1.31 (1.13 to 1.53) |
| Experienced homelessness | 2.10 (1.26 to 3.48) | 1.83 (1.10 to 3.04) | 1.15 (0.67 to 1.96) |
| Mental health or addiction concerns | 1.53 (1.38 to 1.69) | 1.51 (1.36 to 1.67) | 1.14 (1.02 to 1.27) |
| Violence/woman abuse | 1.56 (1.28 to 1.89) | 1.43 (1.18 to 1.74) | 1.01 (0.82 to 1.24) |
| Use of low-income drug benefits | |||
| Welfare | 1.85 (1.75 to 1.95) | 1.53 (1.44 to 1.62) | 1.22 (1.15 to 1.30) |
| Disability support | 1.91 (1.73 to 2.10) | 1.67 (1.52 to 1.84) | 1.25 (1.13 to 1.39) |
| High prescription costs | 1.40 (1.18 to 1.65) | 1.21 (1.03 to 1.43) | 1.22 (1.03 to 1.44) |
| Other program(s) | 1.02 (0.95 to 1.09) | 1.04 (0.97 to 1.11) | 1.05 (0.98 to 1.13) |
| No claims | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Area-level SES measures, quintiles | |||
| Dependency (reference: Q1) | |||
| Q2 | 1.11 (1.05 to 1.17) | 1.10 (1.05 to 1.16) | 1.00 (0.95 to 1.06) |
| Q3 | 1.15 (1.08 to 1.21) | 1.14 (1.08 to 1.21) | 0.98 (0.92 to 1.04) |
| Q4 | 1.22 (1.15 to 1.30) | 1.23 (1.16 to 1.30) | 1.04 (0.97 to 1.11) |
| Q5 (most dependent) | 1.21 (1.14 to 1.29) | 1.23 (1.16 to 1.31) | 1.02 (0.95 to 1.10) |
| Material deprivation (reference: Q1) | |||
| Q2 | 0.98 (0.92 to 1.04) | 0.97 (0.91 to 1.03) | 0.95 (0.89 to 1.02) |
| Q3 | 1.07 (1.00 to 1.14) | 1.05 (0.98 to 1.12) | 1.02 (0.95 to 1.10) |
| Q4 | 1.14 (1.07 to 1.21) | 1.11 (1.04 to 1.18) | 1.07 (0.99 to 1.16) |
| Q5 (most deprived) | 1.22 (1.15 to 1.29) | 1.12 (1.05 to 1.18) | 1.03 (0.94 to 1.12) |
| Residential instability (reference: Q1) | |||
| Q2 | 1.10 (1.04 to 1.17) | 1.14 (1.07 to 1.21) | 1.03 (0.96 to 1.09) |
| Q3 | 1.10 (1.03 to 1.17) | 1.14 (1.07 to 1.21) | 0.97 (0.91 to 1.04) |
| Q4 | 1.18 (1.11 to 1.25) | 1.21 (1.14 to 1.28) | 0.97 (0.90 to 1.03) |
| Q5 (least stable) | 1.00 (0.94 to 1.06) | 1.07 (1.01 to 1.13) | 0.88 (0.82 to 0.95) |
| Ethnic diversity (reference: Q5) | |||
| Q1 (mostly white) | 1.36 (1.28 to 1.44) | 1.42 (1.33 to 1.51) | 1.29 (1.19 to 1.40) |
| Q2 | 1.41 (1.33 to 1.49) | 1.47 (1.38 to 1.56) | 1.33 (1.24 to 1.43) |
| Q3 | 1.31 (1.23 to 1.38) | 1.37 (1.29 to 1.45) | 1.28 (1.20 to 1.37) |
| Q4 | 1.15 (1.09 to 1.22) | 1.20 (1.14 to 1.27) | 1.17 (1.10 to 1.24) |
| Income (reference: Q5) | |||
| Q1 (lowest income) | 1.21 (1.13 to 1.29) | 1.14 (1.07 to 1.21) | 1.12 (1.01 to 1.24) |
| Q2 | 1.15 (1.08 to 1.23) | 1.14 (1.07 to 1.22) | 1.10 (1.01 to 1.19) |
| Q3 | 1.07 (1.00c to 1.14) | 1.06 (0.99 to 1.13) | 1.03 (0.96 to 1.11) |
| Q4 | 1.05 (0.98 to 1.12) | 1.05 (0.98 to 1.12) | 1.06 (0.99 to 1.14) |
| Birth characteristics | |||
| <6 mo old during RSV season | 1.99 (1.87 to 2.12) | 2.00 (1.87 to 2.14) | 2.01 (1.88 to 2.14) |
| Male sex | 1.27 (1.22 to 1.32) | 1.26 (1.21 to 1.31) | 1.24 (1.20 to 1.29) |
| Multiple birth set | 1.66 (1.52 to 1.80) | 0.74 (0.68 to 0.82) | 0.72 (0.65 to 0.79) |
| Gestational agef | |||
| <28 wGA | 5.52 (4.67 to 6.53) | 2.59 (1.92 to 3.51) | 1.89 (1.39 to 2.57) |
| 28–32 wGA | 2.90 (2.57 to 3.28) | 1.83 (1.50 to 2.24) | 1.32 (1.08 to 1.62) |
| 33–35 wGA | 2.22 (2.04 to 2.41) | 1.81 (1.63 to 2.02) | 1.35 (1.20 to 1.51) |
| 36–38 wGA | 1.41 (1.35 to 1.47) | 1.30 (1.25 to 1.37) | 1.26 (1.21 to 1.32) |
| 39–40 wGA | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| ≥41 wGA | 0.78 (0.72 to 0.84) | 0.86 (0.79 to 0.92) | 0.83 (0.77 to 0.90) |
| Birth wt, gf | |||
| <1500 | 3.92 (3.48 to 4.41) | 1.92 (1.52 to 2.43) | 1.57 (1.24 to 1.99) |
| 1500–1999 | 2.26 (1.99 to 2.55) | 1.45 (1.23 to 1.71) | 1.15 (0.97 to 1.36) |
| 2000–2499 | 1.69 (1.56 to 1.84) | 1.30 (1.18 to 1.43) | 1.15 (1.04 to 1.27) |
| 2500–2999 | 1.17 (1.11 to 1.24) | 1.09 (1.03 to 1.15) | 1.06 (1.00 to 1.13) |
| 3000–3499 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 3500–3999 | 1.03 (0.98 to 1.08) | 1.04 (0.99 to 1.10) | 1.03 (0.98 to 1.08) |
| 4000–4499 | 1.09 (1.02 to 1.18) | 1.09 (1.02 to 1.18) | 1.04 (0.96 to 1.12) |
| ≥4500 | 1.13 (0.97 to 1.32) | 1.09 (0.93 to 1.27) | 1.01 (0.86 to 1.18) |
| Prolonged birth stay (>4 d) | 2.32 (2.20 to 2.44) | 1.79 (1.66 to 1.93) | 1.58 (1.46 to 1.71) |
| Type of labor | |||
| Spontaneous vaginal | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Induced vaginal | 1.08 (1.02 to 1.14) | 1.11 (1.05 to 1.17) | 1.10 (1.04 to 1.16) |
| Uninduced cesarean delivery | 1.18 (1.13 to 1.24) | 1.03 (0.99 to 1.08) | 1.09 (1.04 to 1.15) |
| Induced cesarean delivery | 0.75 (0.68 to 0.83) | 1.05 (0.95 to 1.16) | 1.08 (0.97 to 1.20) |
| Induced and assisted to any mode | 0.66 (0.57 to 0.76) | 0.93 (0.80 to 1.07) | 0.96 (0.83 to 1.11) |
| Other assisted, any mode | 0.72 (0.66 to 0.79) | 0.97 (0.88 to 1.06) | 1.03 (0.93 to 1.13) |
| No. siblings (at birth) | |||
| None | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 1 | 1.91 (1.82 to 2.00) | 1.89 (1.80 to 1.98) | 2.07 (1.96 to 2.18) |
| 2 | 2.32 (2.19 to 2.45) | 2.24 (2.12 to 2.37) | 2.49 (2.34 to 2.65) |
| 3 | 2.81 (2.60 to 3.04) | 2.67 (2.47 to 2.89) | 2.94 (2.70 to 3.21) |
| ≥4 | 3.03 (2.75 to 3.33) | 2.83 (2.57 to 3.12) | 3.20 (2.88 to 3.56) |
| Health status factorsg | |||
| Any major congenital anomaly | 1.82 (1.71 to 1.94) | 1.46 (1.36 to 1.56) | 1.35 (1.26 to 1.45) |
| BPD | 5.61 (4.47 to 7.04) | 1.53 (1.15 to 2.02) | 1.28 (0.96 to 1.70) |
| hs-CHD | 2.22 (1.58 to 3.11) | 1.56 (1.11 to 2.18) | 1.13 (0.80 to 1.59) |
| Trisomy 21 | 5.07 (3.89 to 6.61) | 3.82 (2.92 to 4.98) | 2.67 (2.03 to 3.53) |
| Characteristic . | Unadjusted, RR (95% CI) . | Adjusted,a RR (95% CI) . | Fully Adjusted,b RR (95% CI) . |
|---|---|---|---|
| Demographics (at birth) | |||
| Rural residence | 1.08 (1.01 to 1.14) | 1.03 (0.97 to 1.10) | 0.83 (0.77 to 0.89) |
| Geographic isolation | 0.68 (0.54 to 0.86) | 0.53 (0.39 to 0.72) | 0.44 (0.31 to 0.60) |
| Mother’s immigration status | |||
| Canadian born | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Long-term immigrant | 0.82 (0.78 to 0.86) | 0.73 (0.70 to 0.77) | 0.88 (0.83 to 0.93) |
| Recent immigrant | 0.61 (0.56 to 0.66) | 0.64 (0.59 to 0.70) | 0.76 (0.70 to 0.83) |
| Recent refugee | 0.94 (0.79 to 1.12) | 0.79 (0.66 to 0.94) | 0.83 (0.70 to 1.00c) |
| Maternal social vulnerabilitiesd | |||
| Child apprehended at birth | 2.00 (1.61 to 2.49) | 1.52 (1.22 to 1.89) | 0.98 (0.78 to 1.26) |
| Maternal age at birth, ye | |||
| <20 | 1.37 (1.22 to 1.53) | 1.75 (1.56 to 1.97) | 1.50 (1.33 to 1.70) |
| 20–24 | 1.32 (1.24 to 1.40) | 1.36 (1.28 to 1.45) | 1.23 (1.15 to 1.32) |
| 25–29 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 30–34 | 1.05 (1.00c to 1.10) | 0.86 (0.82 to 0.90) | 0.89 (0.85 to 0.94) |
| 35–39 | 0.96 (0.91 to 1.02) | 0.72 (0.68 to 0.77) | 0.76 (0.71 to 0.81) |
| ≥40 | 0.83 (0.74 to 0.92) | 0.56 (0.50 to 0.63) | 0.59 (0.53 to 0.67) |
| Criminal justice system involvement | 1.43 (1.23 to 1.65) | 1.33 (1.15 to 1.54) | 1.31 (1.13 to 1.53) |
| Experienced homelessness | 2.10 (1.26 to 3.48) | 1.83 (1.10 to 3.04) | 1.15 (0.67 to 1.96) |
| Mental health or addiction concerns | 1.53 (1.38 to 1.69) | 1.51 (1.36 to 1.67) | 1.14 (1.02 to 1.27) |
| Violence/woman abuse | 1.56 (1.28 to 1.89) | 1.43 (1.18 to 1.74) | 1.01 (0.82 to 1.24) |
| Use of low-income drug benefits | |||
| Welfare | 1.85 (1.75 to 1.95) | 1.53 (1.44 to 1.62) | 1.22 (1.15 to 1.30) |
| Disability support | 1.91 (1.73 to 2.10) | 1.67 (1.52 to 1.84) | 1.25 (1.13 to 1.39) |
| High prescription costs | 1.40 (1.18 to 1.65) | 1.21 (1.03 to 1.43) | 1.22 (1.03 to 1.44) |
| Other program(s) | 1.02 (0.95 to 1.09) | 1.04 (0.97 to 1.11) | 1.05 (0.98 to 1.13) |
| No claims | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Area-level SES measures, quintiles | |||
| Dependency (reference: Q1) | |||
| Q2 | 1.11 (1.05 to 1.17) | 1.10 (1.05 to 1.16) | 1.00 (0.95 to 1.06) |
| Q3 | 1.15 (1.08 to 1.21) | 1.14 (1.08 to 1.21) | 0.98 (0.92 to 1.04) |
| Q4 | 1.22 (1.15 to 1.30) | 1.23 (1.16 to 1.30) | 1.04 (0.97 to 1.11) |
| Q5 (most dependent) | 1.21 (1.14 to 1.29) | 1.23 (1.16 to 1.31) | 1.02 (0.95 to 1.10) |
| Material deprivation (reference: Q1) | |||
| Q2 | 0.98 (0.92 to 1.04) | 0.97 (0.91 to 1.03) | 0.95 (0.89 to 1.02) |
| Q3 | 1.07 (1.00 to 1.14) | 1.05 (0.98 to 1.12) | 1.02 (0.95 to 1.10) |
| Q4 | 1.14 (1.07 to 1.21) | 1.11 (1.04 to 1.18) | 1.07 (0.99 to 1.16) |
| Q5 (most deprived) | 1.22 (1.15 to 1.29) | 1.12 (1.05 to 1.18) | 1.03 (0.94 to 1.12) |
| Residential instability (reference: Q1) | |||
| Q2 | 1.10 (1.04 to 1.17) | 1.14 (1.07 to 1.21) | 1.03 (0.96 to 1.09) |
| Q3 | 1.10 (1.03 to 1.17) | 1.14 (1.07 to 1.21) | 0.97 (0.91 to 1.04) |
| Q4 | 1.18 (1.11 to 1.25) | 1.21 (1.14 to 1.28) | 0.97 (0.90 to 1.03) |
| Q5 (least stable) | 1.00 (0.94 to 1.06) | 1.07 (1.01 to 1.13) | 0.88 (0.82 to 0.95) |
| Ethnic diversity (reference: Q5) | |||
| Q1 (mostly white) | 1.36 (1.28 to 1.44) | 1.42 (1.33 to 1.51) | 1.29 (1.19 to 1.40) |
| Q2 | 1.41 (1.33 to 1.49) | 1.47 (1.38 to 1.56) | 1.33 (1.24 to 1.43) |
| Q3 | 1.31 (1.23 to 1.38) | 1.37 (1.29 to 1.45) | 1.28 (1.20 to 1.37) |
| Q4 | 1.15 (1.09 to 1.22) | 1.20 (1.14 to 1.27) | 1.17 (1.10 to 1.24) |
| Income (reference: Q5) | |||
| Q1 (lowest income) | 1.21 (1.13 to 1.29) | 1.14 (1.07 to 1.21) | 1.12 (1.01 to 1.24) |
| Q2 | 1.15 (1.08 to 1.23) | 1.14 (1.07 to 1.22) | 1.10 (1.01 to 1.19) |
| Q3 | 1.07 (1.00c to 1.14) | 1.06 (0.99 to 1.13) | 1.03 (0.96 to 1.11) |
| Q4 | 1.05 (0.98 to 1.12) | 1.05 (0.98 to 1.12) | 1.06 (0.99 to 1.14) |
| Birth characteristics | |||
| <6 mo old during RSV season | 1.99 (1.87 to 2.12) | 2.00 (1.87 to 2.14) | 2.01 (1.88 to 2.14) |
| Male sex | 1.27 (1.22 to 1.32) | 1.26 (1.21 to 1.31) | 1.24 (1.20 to 1.29) |
| Multiple birth set | 1.66 (1.52 to 1.80) | 0.74 (0.68 to 0.82) | 0.72 (0.65 to 0.79) |
| Gestational agef | |||
| <28 wGA | 5.52 (4.67 to 6.53) | 2.59 (1.92 to 3.51) | 1.89 (1.39 to 2.57) |
| 28–32 wGA | 2.90 (2.57 to 3.28) | 1.83 (1.50 to 2.24) | 1.32 (1.08 to 1.62) |
| 33–35 wGA | 2.22 (2.04 to 2.41) | 1.81 (1.63 to 2.02) | 1.35 (1.20 to 1.51) |
| 36–38 wGA | 1.41 (1.35 to 1.47) | 1.30 (1.25 to 1.37) | 1.26 (1.21 to 1.32) |
| 39–40 wGA | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| ≥41 wGA | 0.78 (0.72 to 0.84) | 0.86 (0.79 to 0.92) | 0.83 (0.77 to 0.90) |
| Birth wt, gf | |||
| <1500 | 3.92 (3.48 to 4.41) | 1.92 (1.52 to 2.43) | 1.57 (1.24 to 1.99) |
| 1500–1999 | 2.26 (1.99 to 2.55) | 1.45 (1.23 to 1.71) | 1.15 (0.97 to 1.36) |
| 2000–2499 | 1.69 (1.56 to 1.84) | 1.30 (1.18 to 1.43) | 1.15 (1.04 to 1.27) |
| 2500–2999 | 1.17 (1.11 to 1.24) | 1.09 (1.03 to 1.15) | 1.06 (1.00 to 1.13) |
| 3000–3499 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 3500–3999 | 1.03 (0.98 to 1.08) | 1.04 (0.99 to 1.10) | 1.03 (0.98 to 1.08) |
| 4000–4499 | 1.09 (1.02 to 1.18) | 1.09 (1.02 to 1.18) | 1.04 (0.96 to 1.12) |
| ≥4500 | 1.13 (0.97 to 1.32) | 1.09 (0.93 to 1.27) | 1.01 (0.86 to 1.18) |
| Prolonged birth stay (>4 d) | 2.32 (2.20 to 2.44) | 1.79 (1.66 to 1.93) | 1.58 (1.46 to 1.71) |
| Type of labor | |||
| Spontaneous vaginal | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Induced vaginal | 1.08 (1.02 to 1.14) | 1.11 (1.05 to 1.17) | 1.10 (1.04 to 1.16) |
| Uninduced cesarean delivery | 1.18 (1.13 to 1.24) | 1.03 (0.99 to 1.08) | 1.09 (1.04 to 1.15) |
| Induced cesarean delivery | 0.75 (0.68 to 0.83) | 1.05 (0.95 to 1.16) | 1.08 (0.97 to 1.20) |
| Induced and assisted to any mode | 0.66 (0.57 to 0.76) | 0.93 (0.80 to 1.07) | 0.96 (0.83 to 1.11) |
| Other assisted, any mode | 0.72 (0.66 to 0.79) | 0.97 (0.88 to 1.06) | 1.03 (0.93 to 1.13) |
| No. siblings (at birth) | |||
| None | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 1 | 1.91 (1.82 to 2.00) | 1.89 (1.80 to 1.98) | 2.07 (1.96 to 2.18) |
| 2 | 2.32 (2.19 to 2.45) | 2.24 (2.12 to 2.37) | 2.49 (2.34 to 2.65) |
| 3 | 2.81 (2.60 to 3.04) | 2.67 (2.47 to 2.89) | 2.94 (2.70 to 3.21) |
| ≥4 | 3.03 (2.75 to 3.33) | 2.83 (2.57 to 3.12) | 3.20 (2.88 to 3.56) |
| Health status factorsg | |||
| Any major congenital anomaly | 1.82 (1.71 to 1.94) | 1.46 (1.36 to 1.56) | 1.35 (1.26 to 1.45) |
| BPD | 5.61 (4.47 to 7.04) | 1.53 (1.15 to 2.02) | 1.28 (0.96 to 1.70) |
| hs-CHD | 2.22 (1.58 to 3.11) | 1.56 (1.11 to 2.18) | 1.13 (0.80 to 1.59) |
| Trisomy 21 | 5.07 (3.89 to 6.61) | 3.82 (2.92 to 4.98) | 2.67 (2.03 to 3.53) |
Adjusted for age (<6 mo) during RSV season, gestational age, birth wt, hs-CHD, BPD, trisomy 21, sex, birth set, and sibling count.
Adjusted for all factors in this table.
Rounded up.
Specific to the 2 y before birth, unless otherwise noted.
Maternal age at first and current birth were highly correlated; age at first birth was excluded from the fully adjusted model, given its weaker association with RSV outcomes.
The 28 to 32 wGA category had a low correlation with birth weights of 1500 to 2000 g (correlation coefficient = −0.49), and the 33 to 35 wGA group had a low correlation with birth weights of 1500 to 2000 g (−0.31) and 2000 to 2500 g (−0.35); thus, both variables were included in the final adjusted model.
Palivizumab eligibility was highly correlated with multiple variables and, thus, excluded from the fully adjusted model in favor of more specific characteristics. The crude RR for palivizumab-eligible children was 3.20 (95% CI: 2.91 to 3.52) and 0.68 (95% CI: 0.52 to 0.90) in the adjusted model.