Cross-Sectional Cohort Design Offers an Efficient Alternative to Prospective Cohort Design in Real-World Studies (RWS)
Author(s)
Neil R. Brett, PhD1, Marielle Bassel, BA1, Vincent McCarty, MSc2, John S. Sampalis, MSc, PhD1.
1PPD™ Observational Studies, Thermo Fisher Scientific, Montreal, QC, Canada, 2Department of Surgery, McGill University, Montreal, QC, Canada.
1PPD™ Observational Studies, Thermo Fisher Scientific, Montreal, QC, Canada, 2Department of Surgery, McGill University, Montreal, QC, Canada.
Presentation Documents
OBJECTIVES: The longitudinal prospective cohort (LPC) study design is often regarded as the gold standard for RWS tracking changes over time in clinical/patient-reported outcomes. However, long durations, regulatory requirements and/or logistical/operational complexities may render this design impractical or cost-prohibitive. The cross-sectional cohort (CSC) design where subjects are assessed once, at varying stages in their disease journey, may be a reasonable alternative. The objective was to compare CSC and LPC designs in patients with Rheumatoid Arthritis (RA).
METHODS: The study utilized real-world data from 1,716 patients with RA receiving treatment (48% on treatment A, 52% on treatment B). Clinical Disease Activity Index (CDAI), Simplified Disease Activity Index (SDAI) and the CRP-based Disease Activity Score 28 (CRP-DAS28) were assessed at treatment initiation and 3,6,9 and 12 months. To simulate the CSC, a single point in time was randomly selected as the hypothetical cross-sectional time of assessment. Data were analyzed using univariate and repeated measures general linear models.
RESULTS: CDAI Least Square Means (LSM) were numerically similar between CSC and LPC designs at 0 (CSC:30.2, LPC:29.8), 3 (CSC:16.9, LPC:16.2), 6 (CSC:16.1, LPC:15.0), 9 (CSC:12.1, LPC:12.1) and 12 months (CSC:11.2, LPC:12.1). Between-treatment LSM differences (SEM) were -0.261 (0.555); P=0.639 and -0.496 (0.369); P=0.179, for CSC and LPC respectively. Given the range of possible CDAI scores (0-80), the difference in effect size estimates is negligible and statistically non-significant (P=0.333). For both designs, the effect of Time (months) was significant (P<0.001) while the interaction of Time x Treatment was not (P>0.15). Similar results were observed for the SDAI and the CRP-DAS28, including no differences in effect size estimates (SDAI: P=0.754, CRP-DAS28: P=0.162).
CONCLUSIONS: Results suggest that the CSC design may be an efficient alternative to LPC in RWS. Potential study and therapeutic area-specific considerations should be understood prior to implementing a CSC design.
METHODS: The study utilized real-world data from 1,716 patients with RA receiving treatment (48% on treatment A, 52% on treatment B). Clinical Disease Activity Index (CDAI), Simplified Disease Activity Index (SDAI) and the CRP-based Disease Activity Score 28 (CRP-DAS28) were assessed at treatment initiation and 3,6,9 and 12 months. To simulate the CSC, a single point in time was randomly selected as the hypothetical cross-sectional time of assessment. Data were analyzed using univariate and repeated measures general linear models.
RESULTS: CDAI Least Square Means (LSM) were numerically similar between CSC and LPC designs at 0 (CSC:30.2, LPC:29.8), 3 (CSC:16.9, LPC:16.2), 6 (CSC:16.1, LPC:15.0), 9 (CSC:12.1, LPC:12.1) and 12 months (CSC:11.2, LPC:12.1). Between-treatment LSM differences (SEM) were -0.261 (0.555); P=0.639 and -0.496 (0.369); P=0.179, for CSC and LPC respectively. Given the range of possible CDAI scores (0-80), the difference in effect size estimates is negligible and statistically non-significant (P=0.333). For both designs, the effect of Time (months) was significant (P<0.001) while the interaction of Time x Treatment was not (P>0.15). Similar results were observed for the SDAI and the CRP-DAS28, including no differences in effect size estimates (SDAI: P=0.754, CRP-DAS28: P=0.162).
CONCLUSIONS: Results suggest that the CSC design may be an efficient alternative to LPC in RWS. Potential study and therapeutic area-specific considerations should be understood prior to implementing a CSC design.
Conference/Value in Health Info
2025-11, ISPOR Europe 2025, Glasgow, Scotland
Value in Health, Volume 28, Issue S2
Code
SA25
Topic
Clinical Outcomes, Study Approaches
Disease
Systemic Disorders/Conditions (Anesthesia, Auto-Immune Disorders (n.e.c.), Hematological Disorders (non-oncologic), Pain)