Formula for emergency physician staffing.

Estimates of emergency physician needs traditionally have relied on calculations based on the number of patients seen by the emergency physician (volume formula). We have found this model has not predicted accurately manpower needs in our emergency department as the case mix of services has changed. The "LIVES" formula estimates the amount of time emergency physicians provide services by using Length of stay, intensity of services, and Service type in addition to the traditional factors (Volume of patients, Efficiency of physicians). Thirteen years of statistics from our emergency department were used to examine the performance of the two formulas in predicting changes in the amount of physician services. The LIVES formula performed better than the volume formula: a better fit with number of physicians used by chi 2 analysis (chi 2 = 1084 versus 5591), a better correlation with physicians used (regression coefficient 0.98 v 0.21), a higher degree of association with physicians used (correlation coefficient 0.96 versus 0.53 with P less than 0.0001 v 0.06 by Student's t-test), and explained more of the variability in the amount of physicians used (92% v 28%). Changes in types of services provided by the modern emergency department require multifactorial analysis to determine manpower needs.