The Long-Term Care Data Cooperative: The Next Generation of Data Integration.

Despite important advances in the linkage of residents' Medicare claims and Minimum Data Set (MDS) information, the data infrastructure for long-term care remains inadequate for public health surveillance and clinical research. It is widely known that the evidence base supporting treatment decisions for older nursing home residents is scant as residents are systematically excluded from clinical trials. Electronic health records (EHRs) hold the promise to improve this population's representation in clinical research, especially with the more timely and detailed clinical information available in EHRs that are lacking in claims and MDS.

Consequences of Depletion of Susceptibles for Hazard Ratio Estimators Based on Propensity Scores.

We use simulated data to examine the consequences of depletion of susceptibles for hazard ratio (HR) estimators based on a propensity score (PS). First, we show that the depletion of susceptibles attenuates marginal HRs toward the null by amounts that increase with the incidence of the outcome, the variance of susceptibility, and the impact of susceptibility on the outcome. If susceptibility is binary then the Bross bias multiplier, originally intended to quantify bias in a risk ratio from a binary confounder, also quantifies the ratio of the instantaneous marginal HR to the conditional HR as susceptibles are depleted differentially.