An implantable medical device comprising: communication circuity configured to establish a communication link and transfer data between the IMD intra-corpus and a computing device extra-corpus; accelerometer circuitry configured to generate a plurality of signals including a sagittal axis signal, a vertical axis signal and a transverse axis signal; and processing circuitry configured to: calculate a plurality of patient-specific functional status parameters for a plurality of periods associated with a Sit-To-Stand test of two or more Sit-To-Stand tests from at least one of the sagittal axis signal, the vertical axis signal and the transverse axis signal; identify a difference metric value for each of the plurality of patient functional status parameters for the current period and an immediate preceding value of the patient functional status parameter for the immediately preceding period to generate a set of difference metric values for the period, calculate a score for the period based on the set of difference metric values; determine, based on the score for the period, a patient functional status associated with the patient; and activate the communication circuity to transmit the patient-specific functional status parameter from the IMD to the computing device. communication circuity configured to establish a communication link and transfer data between the IMD intra-corpus and a computing device extra-corpus; accelerometer circuitry configured to generate a plurality of signals including a sagittal axis signal, a vertical axis signal and a transverse axis signal; and processing circuitry configured to: calculate a plurality of patient-specific functional status parameters for a plurality of periods associated with a Sit-To-Stand test of two or more Sit-To-Stand tests from at least one of the sagittal axis signal, the vertical axis signal and the transverse axis signal; identify a difference metric value for each of the plurality of patient functional status parameters for the current period and an immediate preceding value of the patient functional status parameter for the immediately preceding period to generate a set of difference metric values for the period, calculate a score for the period based on the set of difference metric values; determine, based on the score for the period, a patient functional status associated with the patient; and activate the communication circuity to transmit the patient-specific functional status parameter from the IMD to the computing device. calculate a plurality of patient-specific functional status parameters for a plurality of periods associated with a Sit-To-Stand test of two or more Sit-To-Stand tests from at least one of the sagittal axis signal, the vertical axis signal and the transverse axis signal; identify a difference metric value for each of the plurality of patient functional status parameters for the current period and an immediate preceding value of the patient functional status parameter for the immediately preceding period to generate a set of difference metric values for the period, calculate a score for the period based on the set of difference metric values; determine, based on the score for the period, a patient functional status associated with the patient; and activate the communication circuity to transmit the patient-specific functional status parameter from the IMD to the computing device.