Table 2. Estimated Coefficients for All Models Trained on the Entire 2013 Training Data Set, Stratified by Age.
| Variable | Estimated coefficients by age group | |||||
|---|---|---|---|---|---|---|
| 18-64 y | ≥65 y | |||||
| Stepwise | LASSO | Ridge | Stepwise | LASSO | Ridge | |
| Intercept | –3.91 | –3.91 | –3.19 | –0.60 | –0.73 | –0.81 |
| Women | 0.22 | 0.21 | 0.17 | –0.09 | –0.09 | –0.08 |
| Age | 0.032 | 0.032 | 0.025 | –0.015 | –0.014 | –0.008 |
| Ethnicity | ||||||
| Asian | 1 [Reference] | 1 [Reference] | 1 [Reference] | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Black | –0.21 | –0.10 | –0.09 | –0.22 | –0.12 | –0.12 |
| Mixed | –0.076 | NAa | 0.022 | –0.073 | NAa | 0.025 |
| Other | –0.060 | NAa | 0.024 | –0.072 | NAa | –0.005 |
| Unknown | –0.22 | –0.14 | –0.10 | –0.18 | –0.10 | –0.08 |
| White | –0.071 | NAa | 0.034 | –0.037 | 0.026 | 0.055 |
| Patient IMD | ||||||
| 1, Least deprived | NAb | NAb | NAb | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| 2 | NAb | NAb | NAb | –0.087 | –0.047 | –0.028 |
| 3 | NAb | NAb | NAb | –0.092 | –0.053 | –0.040 |
| 4 | NAb | NAb | NAb | –0.140 | –0.095 | –0.071 |
| 5, Most deprived | NAb | NAb | NAb | –0.110 | –0.067 | –0.059 |
| Smoking status | ||||||
| Never | 1 [Reference] | 1 [Reference] | 1 [Reference] | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Current | –0.12 | –0.11 | –0.10 | –0.24 | –0.23 | –0.21 |
| Former | 0.061 | 0.054 | 0.086 | 0.073 | 0.068 | 0.077 |
| Unknown | –0.74 | –0.61 | –0.50 | –0.26 | –0.22 | –0.29 |
| Pneumococcal vaccination | 1.07 | 1.07 | 0.96 | 1.48 | 1.48 | 1.30 |
| Prior season SIV uptake | 3.06 | 3.05 | 2.43 | 3.60 | 3.60 | 2.99 |
| Pregnant | 1.80 | 1.76 | 1.24 | NAc | NAc | NAc |
| Chronic renal disease | 0.32 | 0.26 | 0.25 | NAa | –0.01 | –0.02 |
| Chronic heart disease | 0.42 | 0.39 | 0.30 | 0.11 | 0.09 | 0.08 |
| Chronic respiratory disease | 0.20 | 0.16 | 0.02 | 0.06 | 0.05 | 0.06 |
| Chronic liver disease | NAa | NAa | 0.008 | NAa | 0.020 | 0.024 |
| Diabetes | 0.88 | 0.85 | 0.69 | 0.15 | 0.13 | 0.12 |
| Immunosuppression | 0.52 | 0.46 | 0.35 | 0.13 | 0.10 | 0.08 |
| Chronic neurological disease | 0.68 | 0.64 | 0.48 | NAa | NAa | –0.01 |
| Obesity | ||||||
| Morbid (BMI ≥40) | –0.27 | –0.26 | –0.27 | –0.11 | –0.10 | –0.10 |
| Unknown | –0.41 | –0.40 | –0.39 | –0.14 | –0.13 | –0.20 |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); IMD, Indices of Multiple Deprivation; LASSO, least absolute shrinkage and selection operator; NA, not applicable; SIV, seasonal influenza vaccine.
a
Variable removed by autonomous feature selection (stepwise and LASSO only).
b
Patient IMD manually excluded from models among patients aged 18 to 64 years because of consistent insignificance.
c
Variable excluded from models for patients aged 65 years or more because of lack of pregnancy records.