Younger vs. Older Donors in Allo-HSCT: TTE

Prognostic Comparison of Allogeneic Hematopoietic Stem Cell Transplantation Using Younger Versus Older Donors: A Target Trial Emulation Study

Hematopoietic stem cell transplantation is an important therapeutic approach for hematologic malignancies, and the impact of donor age on transplant outcomes remains an active area of investigation. Older donors may be associated with impaired stem cell fitness, delayed immune reconstitution, and reduced T-cell function. However, randomized controlled trials directly comparing transplant outcomes by donor age are difficult to conduct because of ethical constraints, and previous retrospective studies have yielded inconsistent findings due to confounding bias and limited causal interpretability. Target trial emulation (TTE) is a methodological framework that uses observational data to emulate the design principles of a randomized trial, thereby reducing biases such as immortal time bias, time-varying confounding, and prevalent-user bias, and improving the validity of causal inference. Therefore, this study will use a large single-center retrospective clinical cohort to perform a TTE analysis, aiming to approximate the causal framework of an randomized trial and systematically evaluate the effect of donor age on clinical outcomes after allo-HSCT, thereby providing higher-quality evidence to optimize donor selection strategies.

Study Overview

• Status: Not yet recruiting
• Conditions: ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION; A Target Trial Emulation Study; Donor Age

• Study Type: Observational
• Enrollment (Estimated): 5000

Contacts and Locations

• Study Contact: Name: Yang Xu; Phone Number: +86-512-67781850; Email: xuyang1020@126.com

Study Locations

• China
  • Jiangsu
    • Suzhou, Jiangsu, China, 215000
      • The First Affiliated Hospital Of Soochow University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

This study includes adult patients with hematologic malignancies who underwent allogeneic hematopoietic stem cell transplantation at the study center. Eligible patients will be identified from retrospective clinical records and grouped according to donor age recorded at the time of transplantation.

Description

Inclusion Criteria:

• Age 18 years or older.
• Diagnosis of hematologic malignancy.
• Underwent first allogeneic hematopoietic stem cell transplantation.
• HLA matching level of 0.5 or higher.
• Available donor age information.
• Available clinical follow-up and outcome data.

Exclusion Criteria:

• Previous autologous or allogeneic hematopoietic stem cell transplantation.
• HLA matching level below 0.5.
• Missing donor age information.
• Missing key exposure-defining or outcome-defining data required for the analysis.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Younger Donor Group; Patients who underwent allogeneic hematopoietic stem cell transplantation with donors younger than 50 years. Grouping was based on donor age recorded in retrospective clinical data.
Older Donor Group; Patients who underwent allogeneic hematopoietic stem cell transplantation with donors aged 50 years or older. Grouping was based on donor age recorded in retrospective clinical data.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Overall Survival	Overall survival was defined as the interval between hematopoietic stem cell transplantation and death from any cause.	From the date of transplantation to the date of death from any cause or last follow-up, assessed up to 15 years.

Collaborators and Investigators

• Sponsor: The First Affiliated Hospital of Soochow University

Study record dates

Study Major Dates

• Study Start (Estimated): July 15, 2026
• Primary Completion (Estimated): July 15, 2026
• Study Completion (Estimated): December 21, 2027

Study Registration Dates

• First Submitted: June 15, 2026
• First Submitted That Met QC Criteria: June 22, 2026
• First Posted (Actual): June 24, 2026

Study Record Updates

• Last Update Posted (Actual): June 24, 2026
• Last Update Submitted That Met QC Criteria: June 22, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: TTE DONOR AGE

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No