OBJECTIVES: The bioengineered allogeneic cellularized construct (BACC) is an FDA-approved treatment alternative to autografting for deep partial-thickness (DPT) thermal burns in adults. A Phase IIIb, open-label, single-arm, multicenter, expanded-access study (StrataCAT, NCT04123548) evaluated safety and clinical outcomes of BACC treatment in adults with DPT burns. We investigated the impact of BACC versus autografting on inpatient length of stay (LOS) by comparing data from StrataCAT with an external control arm (ECA) comprising real-world data (RWD).

METHODS: All patients in the single-arm StrataCAT trial received ≤2000 cm² BACC (treated cohort). To establish a comparable ECA, StrataCAT trial inclusion/exclusion criteria were applied to patients in the National Burn Repository who received inpatient autografting. A stabilized-inverse-probability of treatment-weighted estimator was utilized to adjust measured confounders (ie, demographic and clinical covariates) and estimate a causal effect. The outcome of interest was LOS, reported as the average treatment effect on the treated (ATT). An e-value sensitivity analysis was conducted to assess potential hidden biases.

RESULTS: Between the two initial cohorts (BACC, n=47; autograft, n=2641), confounder imbalances were observed in 12 of 19 demographic and clinical covariate categories. Before weighting, the BACC cohort had a higher prevalence of comorbidities and more patients with 2^nd and 3^rd degree burns of 20%–30% and 40%–<50% total body surface area burned than the autograft cohort. After weighting, all 19 covariate categories were balanced in the BACC and weighted autograft cohorts (n=47 in both). The ATT of BACC on LOS was 3.91 days shorter (robust SE=1.99, P=0.04979). The sensitivity analysis revealed this finding may be subject to unmeasured confounding.

CONCLUSIONS: Compared with a similar weighted-ECA, data from a single-arm BACC trial demonstrated BACC treatment reduced LOS by 3.91 days in adults with DPT burns relative to autografting. More RWD are needed to further enhance the robustness of our findings.