Our main outcome measure was categorized as top, average, and bottom productivity. In our prior study [
26], we estimated nurse productivity as the nurse’s individual value-added contribution to improvement in the patient’s clinical condition score [
27‐
29] among patients assigned to the nurse’s care. We used Value-Added Methodology [
30] to, first, attribute a change in each patient’s clinical condition score (from admission to discharge) equally to all of the nurses assigned to the patient’s care during hospitalization, and then, for each nurse, compute a risk-adjusted aggregate change in clinical condition scores of the patients linked to the nurse during the study period [
26]. The clinical condition score is a composite metric of 26 clinical parameters from the patient’s electronic medical record including nurse assessments (nutritional status, skin, functional status, psycho-emotional status, pain, etc.), vital signs (temperature, blood pressure, etc.) heart rhythms, and lab tests [
27‐
29]. In prior work, the score was shown to have construct validity for overall patient clinical condition and was predictive of discharge disposition [
27], mortality [
27‐
29], cardiac and pulmonary arrest [
31], and readmission [
32]. Nurse assessments, an independent functional role of a clinical nurse [
24,
25], account for nearly 70% of the variance in the clinical condition score [
28], supporting the use of this outcome for individual nurse productivity measurement.
Based on this previously derived individual productivity measure, nurses in the bottom and top tertile of the individual productivity distribution were categorized as “bottom” and “top” productivity categories, respectively. The middle one-third of the productivity distribution served as the reference category, or “average” productivity. The three productivity categories were associated with clinically significant differences in patient outcomes among the sample tertiles – average improvement in the patient clinical condition score was 0.03/0.48/0.91 standard deviations in the bottom/average/top productivity category, respectively; unplanned 30-day readmission rates were 18.8/16.8/15.9%; inpatient mortality rates were 4.2/2.6/2.2%.