Techniques for using multiple physiological parameters to provide an early warning for worsening heart failure are described. A system is provided that monitors a multiple diagnostic parameters indicative of worsening heart failure. The parameters preferably include are least one parameter acquired from an implanted device, such as intrathoracic impedance. The system device derives an index of the likelihood of worsening heart failure based upon the parameters using a Bayesian approach and displays the resultant index for review by a physician.