A method for issuing an alert which includes the following steps:—carry out an R analysis on two or more physiological variable inputs;—carry out an N analysis on a primary physiological variable input;—issue an alert if the R analysis confirms a trend for each of the physiological variable inputs and the N analysis shows a statistically significant change in the primary physiological variable input; where the two or more physiological variable inputs include systolic or mean blood pressure and pulse volume, and the primary physiological variable input is systolic or mean blood pressure; such that the alert is a visual, audio, vibratory, tactile or a combination of two or more of these or an alert signal to an output unit configured to output the alert in one of those forms.