A data set is generated by an implanted medical device, during operation of the device. The data set includes data characterizing various physiological states of the patient. The data set is communicated from the device to a patient monitoring apparatus. The patient monitoring apparatus develops its own data set by posing questions to the patient, and optionally by measuring a physiological parameter of the patient, such as weight. The two data sets are combined and are analyzed to determine medical information concerning the patient, such as impending decompensation of heart failure.