1. A method of predicting an impending patient cardiac event, the method comprising: receiving from an adherent device impedance data measured with respect to a patient; receiving from an input mechanism patient descriptive data indicating at least one characteristic of the patient; establishing, via a processor, at least one patient-specific value for the patient based at least in part on the impedance data, wherein establishing at least one patient-specific value comprises processing the impedance data to establish a baseline impedance specific to the patient and a baseline breath parameter specific to the patient and computing a predicted impedance specific to the patient based on the patient descriptive data; making ongoing measurements of the impedance via the adherent device and computing ongoing measurements of the breath parameter via the processor; computing via the processor an impedance index indicative of a change in the impedance relative to the baseline impedance over time; computing via the processor a breath index indicative of a change in the breath parameter relative to the baseline breath parameter over time; computing via the processor a predicted impedance index indicative of a change in the impedance relative to the predicted impedance over time; and generating based at least in part on comparisons of the impedance index, the breath index, and the predicted impedance index with respective preselected thresholds performed by the processor, a patient event prediction output predictive of the impending patient cardiac event.