Multilevel Logistic Regression Analyses With 3 Levels: Child, Family, and General Practitioner (GP)
| Explanatory Variables | Empty Model Intercept (SE) | Model 1a Intercept (SE) | Model 2a,b Intercept (SE) | Model 3a,b Intercept (SE) |
|---|---|---|---|---|
| CI = confidence interval; GP = general practitioner; OR = odds ratio; SE = standard error. | ||||
| a Model 1 (age-groups), model 2 (age-groups, child characteristics), model 3 (age-groups, child characteristics, family characteristics, GP characteristics). | ||||
| b In these models we corrected for the presence of an asthma diagnosis in the child (model 2: OR = 262; 95% CI, 219–312; model 3: OR = 264; 95% CI, 221–315). | ||||
| c The variance at the lowest level (children) is not determined because the outcome is dichotomous. | ||||
| d Correlation between the variances of the 2 defined age-groups on the GP level. | ||||
| e ICC between the 2 upper levels (families and GPs). ICC is the relative contribution of GP to sum of family and GP variance. | ||||
| Age 1–17 y | −2.580 (0.039) | |||
| Age 1–5 y | −2.210 (0.054) | −3.629 (0.100) | −3.645 (0.091) | |
| Age 6–17 y | −2.779 (0.039) | −3.573 (0.071) | −3.605 (0.060) | |
| OR (95% CI) | OR (95% CI) | |||
| Sex, male | 1.25 (1.13–1.39) | 1.25 (1.13–1.39) | ||
| Shortness of breath/dyspnea | 20.7 (14.3–29.9) | 20.2 (13.9–29.2) | ||
| Wheezing | 51.5 (24.7–107) | 49.7 (23.8–104) | ||
| Cough | 6.51 (5.68–7.47) | 6.46 (5.64–7.40) | ||
| Acute bronchitis/bronchiolitis | 9.04 (7.57–10.8) | 8.91 (7.45–10.6) | ||
| Acute upper respiratory tract infection | 1.47 (1.26–1.72) | 1.47 (1.26–1.72) | ||
| Pneumonia | 2.10 (1.44–3.07) | 2.11 (1.44–3.09) | ||
| Allergic rhinitis | 2.12 (1.68–2.69) | 2.10 (1.66–2.67) | ||
| No. of contacts with GP | 1.10 (1.08–1.12) | 1.10 (1.08–1.12) | ||
| Presence of parental asthma | 1.74 (1.41–2.15) | |||
| Prescribing volume of GP | 1.99 (1.60–2.47) | |||
| Patients 0–17 y ≥25% per GP | 0.59 (0.44–0.78) | |||
| Percentage of children with asthma diagnosis per GP | 0.88 (0.83–0.93) | |||
| Variance (SE)c | Variance (SE) | Variance (SE) | Variance (SE) | |
| Between-family variance | 0.567 (0.071) | 0.535 (0.071) | 0.474 (0.112) | 0.471 (0.111) |
| Between-GP variance | ||||
| Age 1–17 y | 0.119 (0.022) | |||
| Age 1–5 y | 0.209 (0.042) | 0.751 (0.134) | 0.547 (0.106) | |
| Age 6–17 y | 0.097 (0.022) | 0.384 (0.071) | 0.214 (0.047) | |
| Covariance | 0.118 (0.025) | 0.479 (0.083) | 0.284 (0.058) | |
| Correlations | Correlations | Correlations | Correlations | |
| Correlation of GP variance between age-groupsd | – | 0.83 | 0.89 | 0.83 |
| Intraclass correlatione | ||||
| Age 1–17 y | 0.17 | |||
| Age 1–5 y | 0.38 | 0.72 | 0.64 | |
| Age 6–17 y | 0.29 | 0.65 | 0.51 | |