Table 3.
Associations between exposures and amoxicillin prescribing during the first 2 years of lifea
| Variable | Amoxicillin prescribing, OR (95% CI) | |||
|---|---|---|---|---|
|
| ||||
| Year 1 | Year 2b | |||
|
| ||||
| Crude | Mutually adjusted (n= 2450) | Crude | Mutually adjusted (n= 2476) | |
| Sex of infant | ||||
| Male | 1.33 (1.13 to 1.58) | 1.36 (1.14 to 1.61) | 1.13 (0.96 to 1.33) | 1.14 (0.96 to 1.34) |
| Female | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) |
|
| ||||
| Mother’s ethnic background | ||||
| White British | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) |
| Pakistani, UK born | 1.44 (1.09 to 1.89) | 1.44 (1.06 to 1.94) | 1.36 (1.04 to 1.77) | 1.46 (1.10 to 1.94) |
| Pakistani, not UK born | 1.48 (1.16 to 1.91) | 1.42 (1.07 to 1.90) | 1.40 (1.10 to 1.77) | 1.56 (1.19 to 2.04) |
| Other | 0.68 (0.51 to 0.90) | 0.70 (0.52 to 0.96) | 0.88 (0.67 to 1.15) | 0.98 (0.74 to 1.31) |
|
| ||||
| Socioeconomic status | ||||
| Least deprived and most educated | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) |
| Employed not materially deprived | 0.82 (0.62 to 1.09) | 0.79 (0.59 to 1.06) | 1.15 (0.88 to 1.50) | 1.13 (0.85 to 1.50) |
| Employed with no access to money | 0.95 (0.72 to 1.25) | 0.92 (0.69 to 1.22) | 1.14 (0.88 to 1.50) | 1.11 (0.85 to 1.46) |
| On benefits but coping | 1.13 (0.88 to 1.45) | 0.92 (0.70 to 1.21) | 1.38 (1.08 to 1.76) | 1.26 (0.97 to 1.64) |
| Most deprived | 1.41 (1.06 to 1.87) | 1.36 (1.00 to 1.86) | 1.28 (0.96 to 1.69) | 1.26 (0.93 to 1.70) |
|
| ||||
| Mother smoking during pregnancy | ||||
| No | 1.00 (ref) | — | 1.00 (ref) | — |
| Yes | 1.02 (0.80 to 1.32) | — | 1.00 (0.78 to 1.27) | — |
|
| ||||
| Congenital anomalies | ||||
| No | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) |
| Yes | 1.78 (1.12 to 2.83) | 1.63 (1.01 to 2.63) | 1.78 (1.11 to 2.83) | 1.57 (0.98 to 2.51) |
|
| ||||
| Gestational age | ||||
| Term/late-term | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) |
| Early/preterm | 0.99 (0.82 to 1.20) | 0.97 (0.80 to 1.18) | 1.22 (1.01 to 1.46) | 1.20 (1.00 to 1.45) |
|
| ||||
| Quarter of birth | ||||
| January–March | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | — |
| April–June | 1.26 (0.99 to 1.60) | 1.33 (1.04 to 1.69) | 1.13 (0.89 to 1.42) | — |
| July–September | 0.99 (0.78 to 1.26) | 0.99 (0.77 to 1.26) | 1.20 (0.95 to 1.51) | — |
| October–December | 0.94 (0.74 to 1.18) | 0.91 (0.71 to 1.15) | 1.27 (1.01 to 1.59) | — |
|
| ||||
| Delivery mode | ||||
| Vaginal | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) |
| Caesarean | 1.21 (0.99 to 1.49) | 1.23 (1.00 to 1.53) | 1.10 (0.90 to 1.35) | 1.08 (0.88 to 1.32) |
|
| ||||
| Breastfeeding duration, months | ||||
| <1 | 1.29 (1.05 to 1.57) | 1.21 (0.97 to 1.50) | 1.29 (1.07 to 1.57) | 1.22 (0.99 to 1.50) |
| 1–<6 | 1.17 (0.93 to 1.47) | 1.11 (0.87 to 1.41) | 1.06 (0.85 to 1.33) | 0.98 (0.78 to 1.24) |
| ≥6 | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) |
|
| ||||
| Quartile of PM2.5 in relation to Bradford levelc | ||||
| 1st/2nd quartile | 1.00 (ref) | — | 1.00 (ref) | 1.00 (ref) |
| 3rd quartile | 1.11 (0.91 to 1.37) | — | 0.99 (0.81 to 1.23) | 0.94 (0.76 to 1.16) |
| 4th quartile | 1.03 (0.78 to 1.36) | — | 1.03 (0.80 to 1.32) | 0.97 (0.75 to 1.26) |
|
| ||||
| Formal childcare | ||||
| No | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) |
| Yes | 0.99 (0.79 to 1.25) | 1.29 (1.00 to 1.66) | 1.22 (0.97 to 1.53) | 1.45 (1.12 to 1.87) |
|
| ||||
| Household mould/damp | ||||
| No mould or damp | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | — |
| Mould or damp | 1.01 (0.82 to 1.23) | 0.98 (0.80 to 1.21) | 0.98 (0.79 to 1.21) | — |
|
| ||||
| Number of people in household | ||||
| 2–5 | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | — |
| ≥6 | 1.54 (1.27 to 1.86) | 1.41 (1.14 to 1.74) | 1.23 (1.02 to 1.49) | — |
|
| ||||
| Cooking type | ||||
| Electric cooking only | 1.00 (ref) | — | 1.00 (ref) | — |
| Electric and gas cooking | 1.14 (0.84 to 1.56) | — | 1.18 (0.84 to 1.66) | — |
| Gas cooking only | 1.17 (0.90 to 1.54) | — | 1.40 (1.05 to 1.86) | — |
|
| ||||
| Intra-GP surgery correlation coefficient | — | 0.09 (0.06 to 0.15) | — | 0.07 (0.04 to 0.11) |
Crude and mutually adjusted models for amoxicillin prescribing during the first and second years of life. All models included GP surgery as the mixed-effect. Mutually adjusted models were adjusted for the mother’s ethnic background, socioeconomic status, and infant sex a priori, as well as: (a) first year of life: congenital anomalies, gestational age, quarter of birth, delivery mode, breastfeeding duration, formal childcare attendance, household mould or damp, and household overcrowding; (b) second year of life: congenital anomalies, gestational age, delivery mode, breastfeeding duration, PM2.5 exposure, and formal childcare attendance.
Models for year 2 include variables imputed using multivariate imputation.
The median and IQR for the absolute PM2.5 levels corresponding to each quartile are displayed in Supplementary Table S3. OR = odds ratio. PM2.5 = particulate matter 2.5 µm. ref = reference.