A comparison of sampling methods to select real-world relapsed/refractory (R/R) diffuse large-cell B-cell lymphoma (DLBCL) patients with multiple eligible index dates
Dillon, P. Surinach, A. Castro, F. Spielewoy, N. Black, J. A. Shang, A. J. Radford, John A
Dillon, P.
Surinach, A.
Castro, F.
Spielewoy, N.
Black, J. A.
Shang, A. J.
Radford, John A
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Abstract
Background: Real world data provide rich longitudinal information on the
entire cycle of care for patients, however sampling R/R DLBCL patient is
challenging due to the presence of multiple eligible index dates per
patient. In the epidemiological literature, potential sampling methods
include to select: 1) the first index, 2) a random index, or 3) all index dates
and statistical ly adjust for within-patient correlation in outcome models.
Objectives: To apply three sampling methods to a retrospective real
world cohort of R/R DLBCL patients and to evaluate differences of
five patient characteristics between each sample by comparing to a
reference sample of R/R DLBLC patients enrolled in the control arm
of a historic clinical trial (NCT02257567).
Methods: Clinical notes from The Christie NHS Foundation trust in
the UK were retrospectively abstracted using a standardized data col-
lection form for 90 patients with R/R DLBCL, aged 18 or older, histo-
logically confirmed DLBCL, at least one prior anti-lymphoma
treatment, who collectively received 192 lines of therapy between
2011-2018. The index date was the start date of each line of therapy.
Characteristics included gender, age at index, no. of prior treatment
lines, refractory disease, and history of stem-cell transplant; the latter
four can vary within patient per eligible index date. The trial enrolled
R/R DLBCL patients, of which 39 participants were randomised to the
control arm. The trial eligibility criteria were applied to the Christie
data resulting in a cohort of 73 patients with 122 eligible index dates.
The three sampling approaches were applied to the eligible cohort,
and the standardized mean difference (SMD) of the patient character-
istics in comparison to the reference sample calculated.
Results: In each sample the SMDs were similar for gender (≈0.05),
index age (≈0.16), and prior transplants (≈0.22); while the all-index
sample yielded the lowest SMDs for refractory disease (0.61) and
no. of prior lines (0.60) in comparison to the reference sample. Proba-
bility sampling of a single index to match the distribution of the no. of
prior lines from the trial was additionally performed, further reducing
SMDs for refractory disease (0.10) and no. of prior lines (0.46) with
similar SMDs to the other samples for the remaining variables.
Conclusions: Each method yielded samples with differences in patient
characteristics, reflected in varying SMDs in comparison to a refer-
ence sample. Thoughtful consideration should be given to sampling
R/R DLBCL patients that should reflect the purpose of the study
Affiliation
Description
Date
2020
Publisher
Collections
Keywords
Type
Meetings and Proceedings
Citation
Dillon P, Surinach A, Castro F, Spielewoy N, Black JA, Shang AJ, et al. A comparison of sampling methods to select real-world relapsed/refractory (R/R) diffuse large-cell B-cell lymphoma (DLBCL) patients with multiple eligible index dates. Pharmacoepidemiology and Drug Safety. 2020;29:430-.