Table 3.
NNT comparison for severe and moderate or severe exacerbations according to prestudy treatment (with as-needed terbutaline as reference treatment) from SYGMA 1
| Overall |
Uncontrolled on BD (Subgroup 1) |
Well Controlled on ICS or LTRA (Subgroup 2) |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| As-needed Terbutaline (N = 1,277) | As-needed BUD–FORM (N = 1,277) | BUD Maintenance + As-needed Terbutaline (N = 1,282) | As-needed Terbutaline (N = 565) | As-needed BUD–FORM (N = 565) | BUD Maintenance + As-needed Terbutaline (N = 576) | As-needed Terbutaline (N = 712) | As-needed BUD–FORM (N = 712) | BUD Maintenance + As-needed Terbutaline (N = 706) | |
| Severe exacerbations | |||||||||
| Patients with ⩾1 exacerbation, n (%) | 152 (11.9) | 71 (5.6) | 78 (6.1) | 51 (9.0) | 23 (4.1) | 35 (6.1) | 101 (14.2) | 48 (6.7) | 43 (6.1) |
| ARR, % (95% CI) | — | 6.34 (4.17 to 8.52) | 5.82 (3.61 to 8.02) | — | 4.96 (2.09 to 7.83) | 2.95 (−0.11 to 6.01) | — | 7.44 (4.29 to 10.60) | 8.09 (4.98 to 11.21) |
| NNT (95% CI) | — | 16 (12 to 24) | 17 (12 to 28) | — | 20 (13 to 48) | 34 (ND) | — | 13 (9 to 23) | 12 (9 to 20) |
| Moderate or severe exacerbations | |||||||||
| Patients with ⩾1 exacerbation, n (%) | 274 (21.5) | 131 (10.3) | 143 (11.2) | 97 (17.2) | 46 (8.1) | 70 (12.2) | 177 (24.9) | 85 (11.9) | 73 (10.3) |
| ARR, % (95% CI) | — | 11.20 (8.40 to 14.00) | 10.30 (7.47 to 13.14) | — | 9.03 (5.19 to 12.87) | 5.02 (0.92 to 9.11) | — | 12.92 (8.95 to 16.89) | 14.52 (10.63 to 18.41) |
| NNT (95% CI) | — | 9 (7 to 12) | 10 (8 to 13) | — | 11 (8 to 19) | 20 (11 to 109) | — | 8 (6 to 11) | 7 (5 to 9) |
Definition of abbreviations: ARR = absolute risk reduction; BD = bronchodilator; CI = confidence interval; BUD = budesonide; FEV1 = forced expiratory volume in 1 second; FORM = formoterol; ICS = inhaled corticosteroid; LTRA = leukotriene receptor antagonist; ND = not done; NNT = number needed to treat; SYGMA = Symbicort Given as Needed in Mild Asthma.
“Uncontrolled on BD” indicates patients whose asthma was uncontrolled on as-needed short-acting BDs. The NNT was calculated by dividing 100 by the difference in the percentage response between the as-needed BUD–FORM and BUD maintenance treatment groups and the reference treatment group (as-needed terbutaline) by using the observed proportion of patients experiencing ⩾1 exacerbation, the total number of exacerbations, and the total exposure (years) during the 1-year study period. CIs for NNTs were calculated as Wald CIs, with the exception of when the ARR was not statistically significant between treatment groups. As the treatment effect approaches zero, the NNT approaches infinity (27).