Algorithm | Eligible population | Questionnaires sent out | Valid returned questionnaires (n, %) | Confirmed asthma cases | PPV (95% CI) |
Specific asthma code + reversibility testing + medication | 36 516 | 92 | 68 (60) | 61 | 86.8 (78.5 to 95.0) |
Specific asthma code + reversibility testing | 38 796 | 90 | 57 (63.3) | 51 | 86.0 (76.7 to 95.3) |
Specific asthma code + medication | 169 574 | 89 | 60 (67.4) | 51 | 83.3 (73.6 to 93.0) |
Specific asthma code | 188 133 | 84 | 59 (70.2) | 51 | 86.4 (77.4 to 95.4) |
Non-specific asthma code + reversibility testing + medication | 33 280 | 78 | 54 (69.2) | 49 | 90.7 (82.8 to 98.7) |
Symptoms + reversibility testing + medication | 53 117 | 87 | 55 (63.2) | 32 | 56.4 (42.8 to 69.9) |
Symptoms + reversibility testing | 66 477 | 88 | 58 (65.9) | 26 | 43.1 (30.0 to 56.2) |
Symptoms + medication | 190 753 | 78 | 64 (82.1) | 38 | 57.8 (45.4 to 70.2) |
Medication use was defined as two prescriptions within 365 days. Evidence of reversibility testing does not hold information on the outcome of these tests.