Table 2.
Adjusted estimated regression coefficients in algorithm derivation
| Coefficient | β-coefficient (SE) | P-value |
|---|---|---|
| Constant | −5.013 | — |
|
| ||
| Factors considered for algorithm | ||
|
| ||
| Age group, years, reference group ≤60 years | ||
| 61–80 | 0.192 (0.076) | 0.01 |
|
| ||
| BMI, kg/m2, reference group 18.5–<25 kg/m2 | ||
| Underweight: <18.5 kg/m2 | 0.597 (0.179) | 0.001 |
| Overweight: 25– <30 kg/m2 | −0.210 (0.087) | 0.02 |
| Obese: ≥30 kg/m2 | −0.103 (0.083) | 0.21 |
|
| ||
| Smoking status, reference group non-smoker | ||
| Current smoker | 0.251 (0.089) | 0.005 |
| Ex-smoker | 0.093 (0.078) | 0.24 |
|
| ||
| Blood eosinophil counts, reference group ≤400/µl | ||
| >400/µl | 0.237 (0.084) | 0.005 |
|
| ||
| Rhinitis diagnosis and/or drugs | −0.212 (0.068) | 0.002 |
|
| ||
| Diabetes diagnosis and/or therapy | 0.378 (0.071) | <0.001 |
|
| ||
| IHD diagnosis | 0.243 (0.116) | 0.036 |
|
| ||
| Anxiety and/or depression | 0.192 (0.068) | 0.005 |
|
| ||
| History of anaphylaxis | 0.790 (0.275) | 0.004 |
|
| ||
| GINA management step, reference group step 1–2 | ||
| No therapy | 0.568 (0.121) | <0.001 |
| Step 3 | 0.101 (0.108) | 0.35 |
| Step 4–5 | 0.461 (0.078) | <0.001 |
|
| ||
| GP consultations for LRTIs | ||
| 1 | 0.313 (0.086) | <0.001 |
| ≥2 | 0.206 (0.122) | 0.09 |
|
| ||
| Acute oral steroids | ||
| 1 | 0.551 (0.095) | <0.001 |
| 2 | 0.975 (0.120) | <0.001 |
| ≥3 | 1.141 (0.107) | <0.001 |
|
| ||
| Paracetamol | 0.204 (0.071) | 0.004 |
|
| ||
| Hospitalisation, HES data | ||
| ≥1 | 1.877 (0.105) | <0.001 |
The pseudo R2 for the equation was 0.0846. Example: for a 24-year-old non-smoker with a BMI of 28 kg/m2, a history of rhinitis, and anxiety, who is receiving Step 3 GINA therapy and has had one course of prednisolone for asthma in the previous year, the at-risk probability = ex/(1 + ex) = e−2.615/(1 + e−2.615) = 0.01, where x = −4.591, calculated from −5.013 (constant) −0.210 (BMI) −0.212 (rhinitis) + 0.192 (anxiety) + 0.101 (asthma treatment) + 0.551 (asthma attacks). BMI = body mass index. GINA = Global Initiative for Asthma. HES = Hospital Episode Statistics. IHD = ischaemic heart disease. LTRI = lower respiratory tract infection. SE = standard error.