Establishing the direct link between individual NVA and a patient's outcomes will demonstrate that the aggregate results are robust to alternative specifications, further strengthening the case for a causal interpretation of the associations consistently found in a variety of settings.
With the objective of understanding the relationship of the relative value-added of individual nurses' contributions to their patients' outcomes, the aims of this study were to (1) estimate the relative nurse effectiveness, or value-added to their patients' clinical condition trajectories during hospitalization; (2) examine the nurse-level associations of nurse human capital measures (education, experience, expertise) and other nurse characteristics (age, gender) to NVA; and (3) examine, at the patient level, the association of nurse effectiveness to patient outcomes (change in clinical condition, length of stay [LOS], costs, 30-day readmission).
To obtain the NVA estimates, we used a covariate-adjustment value-added estimation technique with nurse fixed effects (Murnane 1975; Hanushek 1979; Sanders and Rivers 1996; Sanders, Saxton, and Horn 1997; McCaffrey et al.
We estimated the models for patient outcomes as functions of the NVA of the patient's direct care nurses.
Second, for the second partition (n = 3,492), we constructed a patient-level measure of NVA using a weighted average of nurse fixed effect estimates from the first partition, weighted by the relative frequencies of the patient's contact with each of the nurses during the patient's hospitalization.
We tested whether patients were randomly assigned to nurses, by estimating a linear regression of the patients' admission RI scores on NVA, conditional on patient characteristics, and diagnosis, unit, medical team assignment, and calendar fixed effects, and adjusted for correlation of the error term at the nurse level.
Finally, we estimated multivariate models to examine the association of NVA with patient outcomes using the same approach.
Nurses ranked in the top 20 percent had an average NVA of 5.53 RI points, and nurses in the bottom 20 percent had an average NVA of -4.85 RI points.