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Evaluating the Performance of High-Dimensional Propensity Scores Compared with Standard Propensity Scores for
1Global Real World Evidence, Institut de Recherches Internationales Servier (IRIS), Suresnes, France. virginie.simon@servier.com.
Insights
High-dimensional propensity score (hdPS) matching effectively identifies confounding variables for comparing antihypertensive therapies. Both hdPS and propensity score (PS) matching confirm bitherapy is superior to monotherapy for blood pressure control.
Area of Science:
- Epidemiology and Biostatistics
- Health Services Research
- Pharmacotherapy Research
Background:
- Propensity score (PS) matching is a standard method for creating balanced treatment groups in medical record studies, but requires pre-defined confounding factors.
- High-dimensional propensity score (hdPS) is a semi-automated algorithm designed to identify potential confounders from large medical databases.
Purpose of the Study:
- To evaluate and compare the performance of hdPS and traditional PS matching.
- To assess the effectiveness of these methods in analyzing antihypertensive therapies using the UK Clinical Practice Research Datalink (CPRD) GOLD database.
Main Methods:
- Utilized plasmode simulations with a marginal hazard ratio (HRm) of 1.29 for bitherapy vs. monotherapy for blood pressure control at 3 months.
- Compared hdPS and PS models using either 16 or 36 known covariates, with hdPS additionally selecting 200 variables automatically.
- Conducted sensitivity analyses to evaluate hdPS performance after removing known confounders.
Main Results:
- With 36 covariates, hdPS yielded HRm 1.31 (RMSE 0.05) and PS matching yielded HRm 1.30 (RMSE 0.04).
- With 16 covariates, hdPS yielded HRm 1.23 (RMSE 0.10) and PS yielded HRm 1.09 (RMSE 0.20).
- hdPS performance remained robust even when known confounders were excluded from the analysis.
Conclusions:
- High-dimensional propensity score (hdPS) can identify proxies for unobserved confounders, offering an advantage over traditional PS matching.
- Both PS and hdPS methods demonstrated that bitherapy is superior to monotherapy for achieving blood pressure control.
Introduction:
Propensity score (PS) matching is widely used in medical record studies to create balanced treatment groups, but relies on prior knowledge of confounding factors. High-dimensional PS (hdPS) is a semi-automated algorithm that selects variables with the highest potential for confounding from medical databases. The objective of this study was to evaluate performance of hdPS and PS when used to compare antihypertensive therapies in the UK clinical practice research datalink (CPRD) GOLD database.
Methods:
Patients initiating antihypertensive treatment with either monotherapy or bitherapy were extracted from the CPRD GOLD database. Simulated datasets were generated using plasmode simulations with a marginal hazard ratio (HRm) of 1.29 for bitherapy versus monotherapy for reaching blood pressure control at 3 months. Either 16 or 36 known covariates were forced into the PS and hdPS models, and 200 additional variables were automatically selected for hdPS. Sensitivity analyses were conducted to assess the impact of removing known confounders from the database on hdPS performance.
Results:
With 36 known covariates, the estimated HRm (RMSE) was 1.31 (0.05) for hdPS and 1.30 (0.04) for PS matching; the crude HR was 0.68 (0.61). Using 16 known covariates, the estimated HRm (RMSE) was 1.23 (0.10) and 1.09 (0.20) for hdPS and PS, respectively. Performance of hdPS was not compromised when known confounders were removed from the database.
Results On Real Data:
With 49 investigator-selected covariates, the HR was 1.18 (95% CI 1.10; 1.26) for PS and 1.33 (95% CI 1.22; 1.46) for hdPS. Both methods yielded the same conclusion, suggesting superiority of bitherapy over monotherapy for time to blood pressure control.
Conclusion:
HdPS can identify proxies for missing confounders, thereby having an advantage over PS in case of unobserved covariates. Both PS and hdPS showed superiority of bitherapy over monotherapy for reaching blood pressure control.
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