There is provided an apparatus comprising a control unit and a method (200) of operating the apparatus for receiving an input indicative of one or more symptoms of a subject. Data is acquired on the subject from at least one sensor (202). An input is received from a user interface from the subject indicative of one or more symptoms of the subject (204). An onset time of the one or more symptoms is determined (206) based on the data acquired on the subject from the at least one sensor.
