INTRODUCTION: Contemporary trials of medications to treat hereditary angioedema (HAE) attacks define efficacy endpoints using Patient Global Impression of Severity (PGI-S) and Patient Global Impression of Change (PGI-C) scales; these differ from the visual analog scale (VAS) and treatment effect questionnaire (TEQ) used in legacy recombinant human C1 esterase inhibitor (rhC1-INH) studies. This post hoc analysis aimed to evaluate pooled rhC1-INH trial data, mapped to contemporary HAE clinical trial endpoints and designs.
METHODS: Pooling data from three rhC1-INH trials for acute HAE attacks (NCT00225147, NCT01188564, NCT00262301), this analysis applied results from a bookmarking study to convert TEQ and VAS measurements to PGI-S and PGI-C scales. Kaplan-Meier estimates were calculated for time to complete resolution (TTCR; defined as "none" on PGI-S) and time to onset of symptom relief (TOSR; defined as "a little better" on PGI-C at ≥ 2 consecutive time points within 12 h). Log-rank tests were used to determine differences between treatment groups.
RESULTS: Across trials, 48 and 60 patients received rhC1-INH 50 U/kg and placebo, respectively. The most common attack locations were peripheral (47.9% and 41.7%, respectively) and abdominal (35.4% and 35.0%, respectively). Baseline attack severity was either severe or very severe in all patients. Median [95% confidence interval (CI)] TOSR was 0.75 h (0.55-1.50) with rhC1-INH and 8.00 h (3.00-8.05) with placebo (P < 0.001). Median (95% CI) TTCR was 4.50 h (3.55-5.50) with rhC1-INH and 24.00 h (16.00- > 24.00) with placebo (P < 0.001).
CONCLUSION: This post hoc analysis confirmed that rhC1-INH, compared with placebo, is associated with significantly shorter TOSR and TTCR of HAE attacks.
CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: NCT00225147, NCT01188564, NCT00262301.
Median TOSR was 0.75 h (95% CI, 0.55-1.50) with rhC1-INH and 8.00 h (95% CI, 3.00-8.05) with placebo (P < 0.001)
randomized pooled data show a large contrast, but TOSR depends on post hoc endpoint mapping
Median TTCR was 4.50 h (95% CI, 3.55-5.50) with rhC1-INH and 24.00 h (95% CI, 16.00->24.00) with placebo (P < 0.001)
the large pooled contrast persists across threshold analyses, though TTCR is a mapped rather than measured endpoint
75% of attacks were resolved within 6 h and 90% were resolved by 24 h
landmark Kaplan–Meier estimates support the proportions, subject to the mapped PGI-S definition
rhC1-INH demonstrates significantly faster onset of symptom relief and resolution of HAE attacks compared with placebo, regardless of the efficacy outcome definition used
the placebo contrast is consistent, but “regardless” generalizes beyond the finite mapped definitions tested
Derived from the full evaluation — not a separate score.
Strengths
The TEQ-only TOSR analysis and the VAS ceiling and floor TTCR analyses produced directionally consistent estimates, testing sensitivity to key mapping choices.
↳ Methods, Subgroup and Supportive Analyses; Results, Table 4
The Introduction identifies concrete differences between legacy VAS/TEQ studies and contemporary PGI-S/PGI-C trials, including severity eligibility, treatment timing, and home administration.
↳ Introduction, paragraphs 3–6
The Discussion explains how severe-only enrollment, clinic treatment, interval censoring, missing assessments, and mapped PROs affect precision and generalizability rather than merely listing them.
↳ Discussion, paragraphs 3–7
Limitations
PGI-S and PGI-C were never collected in the source trials; the principal endpoints depend on mappings from legacy VAS and TEQ instruments.
↳ Methods, Assessments; Discussion, final paragraph
Statistical Analysis assigns fixed-window censoring to patients lacking post-baseline assessments, whereas the Discussion also describes censoring at the last evaluable assessment. This limits confidence in exact event-time estimates.
↳ Methods, Statistical Analysis; Discussion, paragraph on interval censoring and missing assessments
All analyzed attacks were severe or very severe, approximately 95% of participants were White, and treatment occurred after clinic evaluation. These conditions differ from broader, earlier home treatment in contemporary care.
↳ Results, Table 1; Discussion, paragraphs 3–6
The analysis adds a practical endpoint-harmonization layer to three legacy randomized, double-blind trials, and the large placebo contrasts in Table 2 are directionally reinforced by the supportive analyses in Table 4. Its contribution remains incremental because the source trials had already established rhC1-INH efficacy. Methodological Rigour is tempered by reliance on mapped PGI endpoints, the inconsistent censoring descriptions in Statistical Analysis and the Discussion, and the unquantified assumption that missingness was nondifferential. The detailed comparison of legacy and contemporary designs strengthens context, but the severe-only, clinic-treated population and absence of a formal adjusted indirect comparison limit broader use.
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Sound3.4
Confidence mediumThe analysis adds a useful bridge by translating legacy VAS and TEQ data into endpoint definitions resembling contemporary HAE trials. Its advance remains incremental because the underlying placebo-controlled efficacy finding was already established.
“The goal of this post hoc analysis was to pool and evaluate TOSR and TTCR”
Kaplan–Meier analyses, symmetric censoring rules, an earlier-treatment subgroup, and supportive mapping-threshold analyses provide competent internal robustness. Confidence is reduced by derived rather than measured PGI endpoints, inconsistent censoring descriptions, and no quantitative assessment of missingness by arm.
“the time-to-event estimates of TOSR and TTCR should be interpreted as approximations”
The paper follows a coherent rationale–methods–results structure and clearly identifies the post hoc mapping approach. The final phrase “regardless of efficacy outcome definition” is broader than warranted by a finite set of mapped and supportive analyses.
“regardless of efficacy outcome definition”
The paper explains how HAE trial endpoints, severity eligibility, treatment timing, and administration settings changed between legacy and contemporary studies. It also traces major limitations to interpretation and states that adjusted indirect comparisons remain future work.
“Future research can build on these results in the form of indirect treatment comparisons”
Caveats4 of 4 checks
The main sample sizes and efficacy estimates reconcile across the abstract, results, and tables. Exact time-to-event interpretation is qualified by inconsistent descriptions of censoring and a terminology slip that calls a 4.50-hour median a hazard ratio.
The analysis identifies the registrations for the source trials and declares that no new human-participant study was conducted, so additional ethics approval was not required. No supplied-text conduct issue met the threshold for elevation.
Flags: 1 declared / 5 total
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No retraction or expression of concern found in Crossref (includes Retraction Watch).
Sources: Crossref (incl. Retraction Watch) ✓
Where this paper’s evidence sits on the path from initial observation to real-world use.
The source intervention has already been evaluated in randomized trials, but this analysis contributes retrospective endpoint harmonization rather than new deployment evidence. Additional adjusted comparative work is required before the mapped results become directly actionable.
“Future research can build on these results”
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