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Estimating antihypertensive effects of combination therapy in an observational study using marginal structural models
Masahiro Sugihara1, Toshio Kushiro, Ikuo Saito
1Department of Industrial Engineering and Management, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan. Sugihara.Masahiro.e5@daiichisankyo.co.jp
Biometrical Journal. Biometrische Zeitschrift
|October 15, 2009
Summary
Marginal structural models (MSMs) with generalized additive models (GAMs) effectively evaluated combination antihypertensive therapy. This approach improved blood pressure control compared to monotherapy in observational studies.
Area of Science:
- Pharmacology
- Biostatistics
- Epidemiology
Background:
- Observational studies evaluating antihypertensive drugs require adjustment for time-dependent confounders.
- Marginal structural models (MSMs) using inverse probability weighting are a common method for confounding adjustment.
- Standard logistic regression for probability estimation in MSMs may inaccurately assume linearity.
Purpose of the Study:
- To propose and evaluate MSMs for assessing the blood pressure-lowering effects of olmesartan medoxomil (OLM) plus calcium channel blockers (CCB) combination therapy.
- To extend MSM probability estimation using generalized additive models (GAMs) for improved confounder balancing.
Main Methods:
- Utilized MSMs with inverse probability weighting to analyze observational data on antihypertensive therapy.
- Employed generalized additive models (GAMs) for estimating probabilities within the MSMs, enhancing confounder distribution balance.
- Compared OLM+CCB combination therapy against OLM monotherapy.
Main Results:
- OLM+CCB combination therapy showed an estimated reduction of -4.3 mmHg in systolic blood pressure (SBP) and -2.9 mmHg in diastolic blood pressure (DBP) after 12 weeks versus OLM monotherapy.
- Target blood pressure achievement rates were higher for OLM+CCB (62.0%) compared to OLM monotherapy (46.7%).
- MSM results aligned better with randomized controlled trial findings than conventional methods.
Conclusions:
- Proposed MSMs with GAMs offer a robust method for evaluating antihypertensive combination therapy in observational studies.
- This methodology provides valuable insights into treatment effectiveness, particularly for combination therapies.
- The findings support the use of advanced statistical models for accurate assessment of real-world antihypertensive treatment effects.
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