Study Selection
Of a total of 4493 abstracts identified in the initial literature search, 510 (11.4%) were assessed to be of interest (Fig. 1). After exclusion of 256 articles, and the addition of four GlaxoSmithKline (GSK) clinical study reports and an additional article retrieved by scanning references, 259 citations were included in the SLR. Parallel online searches of trial registries identified 5838 relevant records. After exclusion of 5650 registries (2304 based on study design, 611 based on population, 997 based on intervention, 79 based on comparator, 12 based on outcomes, 13 based on language, and 1634 duplicates), 188 registries were suitable for inclusion in the SLR. After merging the searches and excluding trials involving non-relevant comparators, we identified a total of 95 citations related to 44 RCTs which were included in the NMA.
Characteristics of the included RCTs are presented in ESM Table S3, and the results of the assessment for risk of bias are summarized in ESM Table S4. Most studies were randomized, double-blind, multicenter trials. Trough FEV1 was the most commonly reported outcome, while rescue medication use was the least common (Table 1). The majority of trials compared TIO [either TIO 18 (18 trials) or TIO 5 (6 trials)] with placebo. Most trials had a duration of either 12–13 weeks (16 trials) or approximately 26 weeks (15 trials). Nine trials had a duration of approximately 1 year, while three trials were longer: the SPARK trial (duration 64 weeks [35]), the TIOSPIR® trial (duration 2.3 years [36]), and the UPLIFT trial (duration 4 years [11]). Nearly all of the trials (40/44) allowed concomitant ICS use; concurrent LABA therapy was allowed in eight trials which compared TIO with placebo, but was not allowed in the trials involving LAMA + LABA therapy.
Table 1 Results of the base case Bayesian network meta-analysis: placebo-adjusted levels of efficacy of each different bronchodilator
Patient Characteristics
Patient characteristics for all included RCTs are presented in Fig. 2. The mean age of patients ranged between 60.5 and 67.9 years, with the percentage of males ranging between 49.5 and 98.5%. The increased variability in gender was largely attributable to three trials comparing TIO with placebo, one of which recruited patients from medical centers for veterans, who are predominantly male. Patients were current smokers (range 26.4–59.5%) or former smokers at study entry, all with a smoking history of >10 pack-years. Most trials included patients with both moderate and severe COPD (GOLD stages II and III); some also included patients with very severe disease (GOLD stage IV). The SPARK trial was a notable exception as it included only patients with severe or very severe COPD, with 76% of patients enrolled using concurrent ICS, and all patients having reported at least one moderate/severe exacerbation in the previous year (Fig. 2) [35].
Bayesian NMA
Because many studies used TIO 18 or TIO 5 as a comparator arm instead of placebo, the base case was performed with studies comparing a LAMA + LABA intervention of interest to another LAMA + LABA intervention of interest or to TIO 18 or TIO 5, or placebo. It was assumed that the results from TIO 18 and TIO 5 were sufficiently similar to be pooled together: similar efficacy and safety have been reported for both doses in a previous NMA [37] and study [38]. A scenario analysis was conducted for trough FEV1 at 12 and 24 weeks to evaluate the impact of pooling the two doses.
The overall networks of studies for the base case analysis for each outcome of interest at 24 weeks are presented in Fig. 3. The individual study results for each outcome of interest are presented in ESM Table S5.
Results are presented for each of the four outcomes of interest (trough FEV1, SGRQ total score, TDI focal score and rescue medication use) for each time point (12 and 24 weeks). For each set of results, results of the base case NMA (with imputation) are presented first, comparing the active therapies with placebo, then the dual therapies with TIO, and finally the dual therapies with each other. Results obtained without imputation of SEs are then briefly summarized, followed by results of the scenario analysis, where applicable. Finally, results of the subgroup analyses are presented.
NMA Results: Trough FEV1
12 Weeks
The base case analysis results at 12 weeks showed that all active therapies achieved improvements in trough FEV1 versus placebo, with probabilities improved outcomes of >99% (Table 1). All improvements were greater than the minimal clinically important difference (MCID) of 100 mL [39]. In comparison with TIO, all combination therapies were superior, with probabilities of improved outcomes of ≥94% (ESM Table S6).
Comparing the combination therapies, the open combination TIO 18 OD + IND 150 OD (TIO + IND) and the FDCs UMEC/VI and GLY/IND (both doses) all had high probabilities (≥94%) of improved outcomes versus the other therapies [TIO 18 OD + FOR 12 BID, ACL/FOR, TIO 18 OD + OLO 5 OD (TIO + OLO) and TIO/OLO]. Between these three therapies, the FDCs appeared to be superior to the open combination, with probabilities of improved outcomes of ≥91%. The probability of improved outcomes using GLY/IND versus UMEC/VI was 78% for the comparison with GLY/IND 27.5/15.6, but only 42% for the comparison with GLY/IND 110/50 (ESM Table S6).
Results using data without imputed SEs were generally similar to the base case results, with only small differences (<5 mL) in changes in FEV1 for most comparisons except those with TIO/OLO for which differences were larger (<15 mL; data not shown). Comparisons with ACL/FOR were not included as these data were obtained by imputation.
In the scenario analysis, separating TIO 18 and TIO 5 had little impact on the base case results (data not shown).
24 Weeks
The base case analysis results at 24 weeks showed that all active therapies achieved improvements in trough FEV1 versus placebo greater than the 100 mL MCID with probabilities of improved outcomes of >99% (Table 1; Fig. 4a). In comparison with TIO, all FDCs demonstrated superiority, with probabilities of improved outcomes of >99% (ESM Table S7). However, the probabilities of improvement versus TIO for the open dual therapies [TIO 18 OD + salmeterol (SAL) 50 BID (TIO + SAL) and TIO 18 + FOR 12] were lower (61% and 56%, respectively).
Comparing the combination therapies, the OD FDCs (UMEC/VI, TIO/OLO, and GLY/IND 110/50) showed the greatest improvements versus placebo and had high probabilities (≥85%) of improved outcomes versus the other therapies (TIO + SAL, TIO 18 + FOR 12, and ACL/FOR). Between the OD FDCs, UMEC/VI had a high probability of improved outcomes versus TIO/OLO (96%; mean difference 23.74 mL; 95% CrI −3.31 to 50.73) and versus GLY/IND 110/50 (84%; mean difference 13.87 mL; 95% CrI −12.98 to 41.33) (ESM Table S7).
Results using data without imputed SEs were similar to the base case results, with only small differences (<5 mL) in changes in FEV1 for all comparisons (data not shown). Results of the scenario analysis (separating TIO 18 and TIO 5) were in line with the base case results, although the probability of improved outcomes with ACL/FOR versus TIO 5 was lower (75%; mean difference 12.57 mL; 95% CrI −22.83 to 49.43) than for the comparison with TIO 5 or 18 (>99%; mean difference 27.33 mL; 95% CrI 5.65 to 48.95).
NMA Results: HRQoL Assessed Using SGRQ Total Score
12 Weeks
The base case analysis results at 12 weeks showed that all active therapies achieved improvements in HRQoL, as shown by decreases in the SGRQ total score, versus placebo, with probabilities of improved outcomes of >99% (Table 1). These decreases were clinically relevant (greater than the MCID of 4 units [40]) for the combination therapies, with the exception of TIO 18 + FOR 12. In comparison with TIO, all therapies showed improvements in HRQoL, with decreases in the SGRQ score of <4 units and probabilities of improved outcomes of >99%, with the exception of TIO 18 + FOR 12 (probability of an improved outcome 75%; mean difference −1.01 units; 95% CrI −3.94 to 1.89) (ESM Table S8).
Comparing the combination therapies, the probabilities of improved outcomes using the FDCs (TIO/OLO, both doses of GLY/IND, and UMEC/VI) and the open dual combination TIO + OLO versus TIO 18 + FOR 12 were relatively high (≥68%). Reductions in the SGRQ score were similar between all FDCs and TIO + OLO, with the probabilities of improved outcomes for comparisons ranging from 38% to 57% (ESM Table S8).
Results with data without imputed SEs were generally similar to the base case results, with relatively small differences (<0.5 units) in changes in the SGRQ score for most comparisons except for those with GLY/IND 110/50, for which differences were greater (<1.1 units; data not shown). Comparisons with TIO 18 + FOR 12 were not included as these data were obtained by imputation.
24 Weeks
The base case analysis results at 24 weeks showed that all active therapies achieved improvements in HRQoL, as shown by decreases in the SGRQ total score, versus placebo, with probabilities of improved outcomes of >99%; these decreases were clinically relevant (>4 units) for GLY/IND 110/50 and UMEC/VI only (Table 1; Fig. 4b). In comparison with TIO, all therapies showed improvements in HRQoL, with decreases in the SGRQ score of <4 units; the probability of improved outcomes was ≥98% for all therapies except for TIO 18 + FOR 10 (71%; mean difference −0.64 units; 95% CrI −2.93 to 1.64) and ACL/FOR (63%; mean difference −0.27 units; 95% CrI −1.89 to 1.36) (ESM Table S9).
Comparing the combination therapies, TIO + SAL and the OD FDCs (TIO/OLO, GLY/IND 110/50, and UMEC/VI) showed relatively high probabilities of improved outcomes versus ACL/FOR (≥83%) and TIO 18 + FOR 10 (≥68%). Improvements using TIO + SAL and the FDCs were similar, although relatively high probabilities of improved outcomes were shown versus TIO/OLO with GLY/IND 110/50 (76%; mean difference −0.53 units; 95% CrI −2.00 to 0.95) and UMEC/VI (67%; mean difference −0.35 units; 95% CrI −1.87 to 1.17).
Results with data without imputed SEs were generally similar to the base case results, with small differences (<0.2 units) in changes in the SGRQ score for most comparisons except those with ACL/FOR, for which differences were greater (<2.3 units; data not shown). With non-imputed data, the probabilities of improvement using ACL/FOR were considerably lower versus placebo (70%; mean difference −0.65 units; 95% CrI −3.07 to 1.80), TIO (8%; mean difference 1.78 units; 95% CrI −0.68 to 4.25) and all other combination therapies (<1–6%) than with imputed data. These differences are due to the inclusion of only a single trial reporting outcomes with ACL/FOR versus placebo in the non-imputed data (the ACLIFORM trial [41]) which reported a mean change from baseline in the SGRQ score of −0.65 units; however, the base case analysis also included the AUGMENT trial [42], which reported a considerably larger mean change from baseline of −4.36 units.
NMA Results: Breathlessness Assessed by TDI Focal Score
12 Weeks
The base case analysis results at 12 weeks showed that all active therapies achieved increases in TDI focal score versus placebo with probabilities of improved outcomes of ≥96% (Table 1). These increases were clinically relevant (greater than the MCID of 1.0 unit [43]) for the FDCs (TIO/OLO, both GLY/IND doses, and UMEC/VI) but not for TIO alone or TIO 18 + FOR 12. In comparison with TIO, the FDCs showed increases in the TDI focal score of <1.0 unit, with high probabilities of improved outcomes (≥96%), while the probability of an improved outcome with TIO 18 + FOR 12 was lower (56%; mean difference 0.07 units; 95% CrI −0.88 to 1.02) (ESM Table S10).
Comparing the combination therapies, the FDCs showed high probabilities of improved outcomes (≥77%) versus the only open dual therapy assessed (TIO 18 + FOR 12). TIO/OLO showed a high probability of improvement versus UMEC/VI (80%); the probability of improvement was also high versus UMEC/VI for GLY/IND 27.5/15.6 (86%) but was lower for GLY/IND 110/50 (61%) (ESM Table S10). No imputation analysis was necessary for these data.
24 Weeks
The base case analysis results at 24 weeks showed that all active therapies achieved increases in TDI focal score versus placebo; the probability of improved outcomes was >99% for all therapies except TIO + SAL (82%; mean difference 0.41 units; 95% CrI −0.46 to 1.27) (Table 1; Fig. 4c). These improvements were clinically relevant (>1.0 unit) for the FDCs (TIO/OLO, GLY/IND 110/50, ACL/FOR, and UMEC/VI) but not for TIO alone or in open dual combination therapy. In comparison with TIO, the FDCs showed increases in TDI focal score of <1.0 unit, with high probabilities of improved outcomes (≥85%); the probabilities with open dual combinations were lower (65% for TIO 18 + FOR 12; 16% for TIO + SAL) (ESM Table S11).
Comparing the combination therapies, the FDCs and TIO 18 + FOR 12 all showed high probabilities (≥85%) of improved outcomes versus TIO + SAL. ACL/FOR and GLY/IND 110/50 showed high probabilities of improved outcomes versus TIO 18 + FOR 12 (91%; mean difference 0.44 units; 95% CrI −0.21 to 1.09; and 96%; mean difference: 0.38 units; 95% CrI: −0.06 to 0.82, respectively). ACL/FOR and GLY/IND 110/50 also showed high probabilities of improved outcomes versus UMEC/VI (91% and 92%, respectively) (ESM Table S11).
Results with data without imputed SEs were similar to the base case results, with only small differences (≤0.08 units) in changes in TDI score for all comparisons (data not shown). With non-imputed data, the probabilities of improvement using ACL/FOR were slightly lower versus TIO (94%; mean difference 0.48 units; 95% CrI −0.12 to 1.07) and all combination therapies (49–96%) than with imputed data.
NMA Results: Puffs/day of Rescue Medication
12 Weeks
The base case analysis results at 12 weeks showed that all active therapies achieved decreases in rescue medication use versus placebo, with probabilities of improved outcomes of ≥93% (Table 1). In comparison with TIO, combination therapies showed decreases in rescue medication use; the probabilities of improved outcomes were >99% for all therapies except TIO 18 + FOR 12 (78%; mean difference −0.25 puffs/day; 95% CrI −0.87 to 0.37) (ESM Table S12).
Comparing the combination therapies, TIO + IND and the FDCs (TIO/OLO, GLY/IND 27.5/15.6, and UMEC/VI) showed high probabilities of improved outcomes (≥82%) versus TIO 18 + FOR 12. TIO + IND showed a high probability of improvement versus TIO/OLO (88%), while both TIO + IND and GLY/IND 27.5/15.6 showed high probabilities of improvement versus UMEC/VI (98% and 94%, respectively) (ESM Table S12). However, a subsequent direct comparison of TIO + IND with UMEC/VI found no significant difference in rescue medication use [44].
Results with data without imputed SEs had no differences from the base case results (data not shown). Comparisons with TIO 18 + FOR 12 and TIO/OLO were not included as these data were obtained by imputation.
24 Weeks
The base case analysis results at 24 weeks showed that all active therapies achieved decreases in rescue medication use versus placebo with probabilities of improved outcomes ≥92% (Table 1; Fig. 4d). In comparison with TIO, the OD FDCs (TIO/OLO, GLY/IND 110/50, and UMEC/VI) showed decreases in rescue medication use with high probabilities (≥87%) of improved outcomes; the probability of improvement with ACL/FOR was lower (51%; mean difference −0.01 puffs/day; 95% CrI −1.22 to 1.26).
Comparing the combination therapies, the OD FDCs showed relatively high probabilities of improved outcomes (≥78%) versus ACL/FOR. Reductions in rescue medication use were similar between the OD FDCs, with the probabilities of improved outcomes for comparisons ranging from 34% to 55% (ESM Table S13).
Results with data without imputed SEs were similar to the base case results, with small differences (≤0.2 puffs per day) in changes in rescue medication use for all comparisons. The probability of an improved outcome using GLY/IND 110/50 versus TIO was higher (>99%; mean difference −0.51 puffs/day; 95% CrI −0.91 to −0.10) than with imputed data. Comparisons with ACL/FOR and TIO/OLO were not included.
Subgroup Analysis
The relative effects of different therapies on trough FEV1 at 12 and 24 weeks were assessed in subgroups of patients using and not using ICS, and in those with moderate disease or severe/very severe disease. Due to the limited data available for these subgroups, only some therapies could be compared. Differences in trough FEV1 at 24 weeks in favor of dual combinations [TIO 18 + FOR 12 and the FDCs (TIO/OLO, GLY/IND 110/50 and UMEC/VI)] versus placebo were greater for patients without ICS use (range 162–280 mL) than for patients with ICS use (range 118–180 mL; ESM Table S14) and for patients with moderate disease (range 147–276 mL) than patients with severe disease (58–119 mL; ESM Table S15). The probabilities of improved outcomes using TIO/OLO or UMEC/VI versus TIO 18 + FOR 12, and UMEC/VI versus TIO/OLO or GLY/IND 110/50, were higher in subgroups without ICS use and in those with moderate disease than in those with ICS use and with severe disease, respectively. However, the probabilities of improved outcomes using TIO 18 + FOR 12 versus TIO and GLY/IND 110/50 versus TIO/OLO were higher in subgroups with ICS use and with severe disease than in patients without ICS use or those with moderate disease, respectively.