Technical Field

[001] The present invention relates to a system and method for determining the Quality of Life (QOL) for a subject utilizing a combination of objective parameters (gait metrics) and subjective parameters (the results of a quality of life questionnaire).

Cross Reference to Related Application

[002] This application claims priority to Australian provisional patent application number 2022902074, filed 25 July 2022, the disclosure of which is incorporated herein by reference.

Background

[003] Conventional medical practice is often not well suited to properly evaluate the ability of a subject to adequately perform day-to-day tasks which can profoundly affect the subject's overall quality of life. The improvement and maintenance of a subject's quality of life can be especially important for elderly subjects and/or these recovering from medical interventions. In these cases, maintaining the subject's quality of life, including mobility, the ability to interact with others in social settings and perform day-to-day tasks, becomes of the utmost importance.

[004] Quality of life is typically described as the degree of well-being felt by an individual and consists of two components, a physical component, and a psychological component. The physical component is influenced by factors such as a subject's mobility, general health, diet, control of pain and progression of disease. The psychological component is influenced by stress, anxiety, pleasure and other positive or negative emotional states. However, the combination of attributes that leads one person to have a high or adequate quality of life is rarely the same for a different person. This diversity makes it difficult to assess the actual quality of life experienced by a person by assessing only external factors. Thus, two people with the same physical health status may in fact be experiencing very different qualities of life.

[005] In clinical practice quality of life is assessed subjectively using a quality of life questionnaire to assess the quality of a subject's life across a broad range of specific areas. These questionnaire based assessments are used to evaluate the effectiveness of therapy, and to suggest areas of an individual’s life that may benefit from modification, intervention or clinical intervention. The questionnaires work best when combined with other sources of information (e.g., medical assessments) although atypical interpretations must be considered in detail on a case-by-case basis.

[006] There remains a need for methods capable of providing a substantially objective measure of the quality of life of individual subjects. There is also a need for methods to evaluate a subject's quality of life and using the evaluations to determine whether treatments or other actions may improve quality of life. [007] The present invention is based on the combination of the results of a subjective quality of life questionnaire and various objective gait parameters, such as, daily step count, average walking speed (gait velocity), and potentially other mobility metrics as predictor or indicator of quality of life.

Summary

[008] In a first aspect there is provided a method for assessing quality of life of a subject, the method comprising: a) obtaining a subjective parameter score from the subject; b) obtaining an objective parameter score from the subject using the gait metrics of gait velocity and total daily step count and optionally any one of more of: i. stride time; ii. stride time variability; iii. stride cadence; iv. step time asymmetry; v. stride length; vi. stride length variability; vii. stride length asymmetry; and viii. gait speed variability; c) combining the subjective parameter score and objective parameter score to generate a SOQOL score of the subject.

[009] The subjective parameter score may be obtained by assigning a numerical value to the subjects answers to a quality of life questionnaire. The numerical values may be summed. In some embodiments the summed numerical values may be scaled, for example to a score out of 50 or 100.

[010] In one embodiment the objective parameter score is obtained by summing the absolute values of the gait metrics. The summed absolute values may be scaled. In some embodiments the summed absolute values are scaled to a score out of 50 or 100.

[011] In one embodiment the subjective parameter score and the objective parameter score are combined by summation to generate the SOQOL score.

[012] In one embodiment the subjective parameter score may be obtained by assigning a numerical value to the subject's answers to a quality of life questionnaire, summing the numerical values and scaling the summed numerical values; the objective parameter score is obtained by summing the absolute values of the gait metrics, and scaling the summed absolute values; and calculating the SOQOL score by summing the subjective and objective parameter scores.

[013] The scaled numerical values may be scaled to a score out of 50 and the scaled absolute values may be scaled to a score out of 50.

[014] In one embodiment a SOQOL score of below 20 indicates an extremely poor quality of life.

[015] In one embodiment a SOQOL score of 20-40 indicates a poor quality of life.

[016] In one embodiment a SOQOL score of 41-60 indicates a fair or average quality of life.

[017] In one embodiment a SOQOL score of 61-80 indicates good quality of life.

[018] In one embodiment a SOQOL score of 81 or more indicates an excellent quality of life.

Definitions

[019] As used herein the term 'IMU' refers to an Inertial Measurement Unit.

[020] The term 'AP' refers to Antero- Posterior.

[021] The term 'ML' refers to Medio-Lateral.

[022] The term 'MEMS' refers to Micro Electro Mechanical Sensors.

[023] Throughout this specification, unless the context clearly requires otherwise, the word 'comprise', or variations such as 'comprises' or 'comprising', will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. [024] Throughout this specification, the term 'consisting of' means consisting only of.

[025] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present technology. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present technology as it existed before the priority date of each claim of this specification.

[026] Unless the context requires otherwise or specifically stated to the contrary, integers, steps, or elements of the technology recited herein as singular integers, steps or elements clearly encompass both singular and plural forms of the recited integers, steps or elements. [027] In the context of the present specification the terms 'a' and 'an' are used to refer to one or more than one (ie, at least one) of the grammatical object of the article. By way of example, reference to 'an element' means one element, or more than one element.

[028] In the context of the present specification the term 'about' means that reference to a figure or value is not to be taken as an absolute figure or value, but includes margins of variation above or below the figure or value in line with what a skilled person would understand according to the art, including within typical margins of error or instrument limitation. In other words, use of the term 'about' is understood to refer to a range or approximation that a person or skilled in the art would consider to be equivalent to a recited value in the context of achieving the same function or result.

[029] Those skilled in the art will appreciate that the technology described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the technology includes all such variations and modifications. For the avoidance of doubt, the technology also includes all of the steps, features, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any two or more of said steps, features and compounds.

[030] In order that the present technology may be more clearly understood, preferred embodiments will be described with reference to the following drawings and examples.

Brief description of the drawings

[031] Embodiments of the systems and methods are described with reference to the following drawings.

[032] Figure 1 is an illustration of a SOQOL score generated on a handheld device. Description of Embodiments

[033] The technology described herein is useful for assessing “quality of life” (QOL) in the context of aged care or recovery from a surgical or medical intervention.

[034] The term QOL is often used to describe the quality of life as it is affected by health and health care. This QOL is distinguished from the subject's “functional status,” which is a term used to describe the subject's ability to function in physical, social and emotional realms. The subject's functional status is a subset of the person's functional capacity, and will vary according to how closely the subject's daily performance approaches their maximal functional capacity. In other words, functional status reflects the objective ability of a subject to perform the tasks of daily life. In contrast, QOL reflects the subjective experience of the impact of health status on the subject's quality of life.

[035] Understanding quality of life is particularly important, as economic measures used to quantify medical success often do not correlate with a subject's QOL. Decisions on how to treat and manage a subject are closely related to their effect on the subject's quality of life. In fact, one of the more important developments in health care may be the recognition that the subject's perspective is an important factor to be considered in the monitoring of health care outcomes. [036] Having an improved and substantially objective method for assessing QOL adds value by providing a better understanding the impact of disease, disability or impact of medical intervention from the subject's perspective has led to the development of instruments to attempt to quantify the subject's perception of their health status before and after treatment. Such instruments seek to measure quality of life via means other than standard objective physiological testing, which typically gives little information about the impact of the condition or treatment from the subject's perspective. In addition, QOL questionnaires are often used in a research setting but provide little, if any, guidance or insight into how to improve individual subjects QOL. For example, while such questionnaires can allow for the tracking and comparison of an individual subject's responses over time, there is currently no standard clinical methodology for objectively quantifying an individual person's quality of life based on such questionnaires. There are also no standard methodologies for using such information about a person's quality of life to modify and/or improve their treatment or sense of well-being and thereby improve the subject's quality of life.

[037] Postural and ambulatory control of balance and stability is an important component of gait. Adequate gait is an important indicator of a subject's functional status an in particular, the objective ability of a subject to perform the tasks of daily life which in turn is linked to the subject's quality of life.

[038] The present invention is directed to methods for determining a subject's QOL from a combination of a questionnaire responses and various gait metrics. The technology uses non- invasive systems and methods to combine subjective and objective assessments of QOL.

Questionnaire

[039] A questionnaire is used to assess the subject's quality of life by evaluating subjective parameters of the subject's health. The parameters relate to the subject's physical and mental health and include but are not limited to aspects of the functional status and functional capacity of the subject, the ability of the subject to perform day-to-day tasks and engage in social activities, the level of pain or discomfort being experienced by the subject, the subject's level of anxiety, and the subject's general sense of well-being.

[040] The questions include, but are not limited, to questions inquiring of: the subject's view of their general health compared to their opinion of their health at a point in the past (e.g. 1 month, six months or twelve mongs ago); the amount or of physical activity the subject is engages in on a regular basis; the ability of the subject to perform day-to-day tasks e.g. walking up stairs, carrying groceries, dressing themselves; the amount of social interaction and/or productive work the subject engages in on a regular basis, and the level of any anxiety experienced during any social contact and/or work; mood, and level of satisfaction felt by the subject; and any depression felt by the subject. The questions are preferably intended to gauge the subject's functional status and the subject's perception of their own functional status and/or physical condition. For example, the subject may be asked both whether they can walk up a flight of stairs as well as whether their ability/inability to do so has adversely impacted them. Further they may be asked whether they think their current condition has improved or worsened over time. [041] The questionnaire may be in a standard form and include various questions to evaluate one or more mental and/or physical health parameters. The questionnaire is preferably provided to the subject on a mobile device such as mobile phone or tablet, and may be completed with assistance from the subject's physician, other medical professional or carer.

[042] Examples of standard form questionaries s that can be used to evaluate parameters relating to the subject's health include any health-related quality of life survey known in the art, such as the Stark QOL, the symptom checklist 27, and the Short Form 36 (SF-36) questionnaire.

[043] In the Stark QoL the first item measures mood and consists of five smileys, at one end is a very happy face, at the other end a very sad one. Subjects are asked to check the one that best applies to them. The second item measures energy and presents two pictures of a person walking, on the left-hand side the walker is full of energy and on the right he seems to be walking almost as if depressed. The third item measures social contact and displays three pictures showing a group of five persons each, one white and four of them grey. The white person symbolizes the proband himself, the grey ones a possible peer group. On one end, the white person is standing in the middle of the group, on the other end alone. Together, these three items constitute the mental component. All items are displayed on one page and are to be answered by making a cross under the picture that best applies to one’s own situation.

[044] On the second page, six items measuring physical functioning are presented. The pictures show activities like carrying a shopping basket, moving a table, tying shoes, etc. Next to each picture, a five point Likert scale was displayed. The text reads "I can", and "++" stands for "very well", " + " for "well", "0" for "fairly", "-" for "poorly" and "- -" for very poorly. Alternatively a sliding scale can be used. Subjects are asked to indicate how easily they can perform the activity displayed in each picture.

[045] The Short Form 36 is a self-rating questionnaire consisting of eight subscales: "Physical Functioning", "Role limitations due to Physical problems", "Bodily Pain", "General Health Perceptions", "Vitality", "Social Functioning", "Role limitations due to Emotional problems", and "Mental Health". The SF-36 has been translated into more than 40 languages and is described in the article “Health-Related Quality of Life in Urban Surgical Emergency Department Subjects: Comparison with a Representative German Population Sample” by Neuner et al., Health and Quality of Life Outcomes 2005, 3:77.

[046] The symptom checklist 27 plus is a six-scale questionnaire that measures depressive symptoms (current and lifetime), symptoms of social anxiety and agoraphobia, vegetative symptoms and symptoms of pain. The scales (except lifetime depression) assess a time frame of two weeks. They comprise between four and six items each, and have good internal consistencies in population as well as subject samples. [047] In some embodiments the methods use bespoke questionnaires. For example a first question may be 'how good is your health today'. The subject can enter an answer to a scale of 1-10 or 1-100 (or any other scale). In some embodiments the subject can enter an answer on using a slider to indicate their answer on a scale with 0 or 1 as a minimum (e.g. indicated by a sad face emoji) and 100 being excellent (e.g. indicated by a smiley emoji).

[048] Other questions are directed to assessing self-care and may include check-box answers to questions such as:

• I have no problems with washing or dressing myself

• I have slight problems with washing or dressing myself

• I have moderate problems with washing or dressing myself

• I have severe problems with washing or dressing myself

• I am unable to wash or dress myself

[049] Other questions are directed to assessing the ability of the subject to perform their usual activities and may include check-box answers to questions such as:

• I have no problems doing my usual activities

• I have slight problems doing my usual activities

• I have moderate problems doing my usual activities

• I have severe problems doing my usual activities

• I am unable to do my usual activities

[050] Other questions are directed to assessing the level of pain or discomfort the subject reports and may include check-box answers to questions such as:

• I have no pain or discomfort

• I have slight pain or discomfort

• I have moderate pain or discomfort

• I have severe pain or discomfort

• I have extreme pain or discomfort

[051] Other questions are directed to assessing the level of anxiety or depression the subject reports and may include check-box answers to questions such as:

• I am not anxious or depressed

• I am slightly anxious or depressed

• I am moderately anxious or depressed

• I am severely anxious or depressed

• I am extremely anxious or depressed

[052] The subject is asked to complete the questionnaire. In this context 'complete' means that the subject is given the opportunity to answer all the questions, and not necessarily that the subject has in fact answered every single question. [053] Once the subjective parameters have been evaluated, a score is assigned to the evaluated parameters. Points are allocated according to the subject's answer for each question, and the points can be totalled to arrive at a 'subjective score' i.e. a score of the subjective QOL parameters. The score may simply be cumulative, or they may be cumulative and then scaled to a score out of 50 or 100 (for example). The points allocated to each answer may also be weighted according to their relative importance.

[054] While obtaining the subjects subjective score is described with particular reference to the completion of at least one questionnaire, it should be understood that the parameters relating to the subject's health can also be evaluated by performing one or more medical diagnostic tests in addition, or as an alternative, to the health evaluation questionnaire. For example assessment for anxiety and or depression may be useful in this context.

Device to measure gait parameters

[055] The methods disclosed herein utilise one or more Inertial Measurement Units (IMUs), typically a mobile phone or a ‘wearable device’ or 'wearable' such as a smart watch or activity tracker. These contain various microelectromechanical sensors (MEMS) including accelerometers, gyroscopes and magnetometers. Wearables can accurately measure numerous gait metrics including gait velocity, stride length, cadence, and step count.

Accordingly, the systems and methods disclosed herein can be used to monitor a subject's gait metrics as part of the QOL assessment.

[056] The IMU contains one or sensor devices that communicate with a processor that can produce information, based on the sensor readings and data, to facilitate the subject or another user, such as a clinician, doctor, hospital, carer, or other appropriate person, monitor the subject.

[057] For example, the wearable device (IMU) may include one or more sensors and may be applied to the skin of a subject. In at least some embodiments, the one or more sensors communicate with a processor. The processor may be in the wearable device or may be remote from it. In some embodiments the sensor device also includes a display. In some embodiments, the processor, the sensors, or both communicate with a display device, such as a mobile phone, tablet, or computer.

[058] In at least some embodiments, the one or more sensors and, preferably, the processor (or multiple processors) are provided in a sensor device that is adapted to be applied to the skin of the subject, carried on an article of clothing or carried on a sling or harness worn by the subject.

[059] The display device can be any suitable device such as a computer (for example, a notebook or laptop computer, a mobile medical station or computer, a server, a mainframe computer, or a desktop computer), mobile devices (for example, a smartphone, smartwatch, or a tablet), or any other suitable device. In some embodiments, the display device can be incorporated into a medical station or system.

[060] In some embodiments the display device is configured to communicate with one or more other devices and can for example alert a subject's clinician, career or other designator person or service. For example, if the gait metrics indicate that the subject has a low QOL an alert may be sent to a carer or clinician.

[061] In one embodiment of the sensor device, the display device, or both have the ability to process data and comprise a memory, a display, and are adapted to receive an input via an input device. In some embodiments these components can be carried by the user (for example if they are part of the sensor device).

[062] The processor is configured to execute instructions provided to the processor. Such instructions can include any of the steps of methods or processes described herein. Any suitable memory can be used for the sensor and display devices. The memory may be any computer-readable storage media such as, non-volatile, non-transitory, removable, and nonremovable computer-readable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data.

[063] In some embodiments, the sensors and processor are continuously active. In other embodiments, the sensors and processor are active intermittently (for example every 0.1 , 0.5, 1, 5, 10, 15, or 30 seconds). Optionally, the period may be programmable. In one embodiment the period is altered based on data from one or more of the sensors. In another other embodiment the sensors and processor are activated manually or automatically by the sensor device or display device. In some embodiments the sensors and processor are activated automatically when the sensor device is put into motion.

[064] In some embodiments, each sensor may have different activation schedules (e.g. continuous, intermittent, manual). For example, a sensor to measure gait velocity or step length may be activated automatically when motion is detected.

[065] The processor can be any suitable processor and may include or be coupled to memory for storing data received from the sensor. The processor can be wired or wirelessly coupled to the sensor. In some embodiments, the processor may include analysis algorithms for analyzing or partially analyzing data received from the sensor. In other embodiments, the processor may be used to receive, store, and transmit data received from the sensors.

[066] The communications unit can be any suitable communications arrangement that can transmit information from the processor or sensors to another device (such as the display device) The communications unit can transmit this information by any suitable wired or wireless technique such as Bluetooth, near field communications, WiFi, infrared, radio frequency, acoustic, optical, or by a wired connection through a data port in the sensor device. [067] The systems and methods can utilise personal characteristics of the subject to assist in determining one or more gait metrics. The personal characteristics can include one or any combination of age, gender, height, weight, level of activity, level of mobility, body mass index (BMI), leg length discrepancy, and surgical procedure. In some embodiments, the gait metrics may differ based on the subject's gender, age, or height (or any other personal characteristic or combination of personal characteristics).

[068] In at least some embodiments, the ranges for the different measurements can be modified for age, gender, height, or other personal characteristics, or any combination thereof. An application on the display device may provide information regarding the measurements (for example, lists of the measurements, graphs of the measurements, averages or daily numbers for the measurements or the like or any combination thereof), as well as any gait metric. The application may allow a user to access to some or all profile details and may permit access to sensor unit set-up and calibration applications or protocols.

Gait Metrics

[069] The methods described herein utilise one or more gait metrics which include walking speed and daily step count and those described below. The gait metrics are objective parameters that can be used to assess QOL.

[070] While the gait metrics can be calculated using any known methods, the exemplary methods below assume that n steps were taken over the entire bout, or for the walking orientation randomness metric calculation, that the bout was n meters long.

[071] ST = stride time, STV = stride time variability, SL = stride length, SLV = stride length variability, GV = gait velocity, GSV = gait speed variability.

. t-i Time of stride i

Equation 1: Average ST = - - ^t - - -

Equation 8:

Equation 9:

Equation 13:

[072] In other embodiments the gait metrics of walking speed and daily step count and optionally any one or more of the metrics described by Equations 1-13 (or by any other means known in the art), can be used to in the assessment of QOL.

[073] Once the gait metrics (objective parameters) have been evaluated, a score is assigned to the evaluated parameters. Either the absolute value of each metric is used or points are allocated according to the measurement for each metric. The absolute value or points can be totalled to arrive at an 'objective score' i.e. a score of the objective QOL parameters. The score may simply be cumulative or may be cumulative and then scaled to a score out of 50 or 100 (for example). The points allocated to each metric may also be weighted according to their relative importance.

[074] In some embodiments the sum of the points allocated to the gait metrics is indicative of QOL. For example if the sum of the points meets or exceeds a predetermined threshold value the objective parameters indicate a good QOL, this is the case for example where the subject's walking speed, total step counts and gait variability are consistent with normative data. Alternatively if the sum of the points falls below a predetermined threshold value the objective parameters indicate a low or poor QOL, this is the case for example where the subject's walking speed, total step counts and gait variability are below normative data.

Combining subjective and objective parameters

[075] Once the subjective score and objective score have been calculated they are combined to provide a 'subjective objective quality of life score' or SOQOL score which is a substantially objective QOL measurement.

[076] In one embodiment each of the subjective and objective scores are scaled to a value out of 50 and the scaled scores are summed to provide a SOQOL score expressed as a number our of 100, with a higher score being indicative of a higher QOL.

[077] In an exemplary embodiment, a high QOL is a score of 80 or more, and medium or acceptable QOL is a score between 40 to 80 and a low (poor) QOL is a score of 40 or below. Examples of middle aged adults in good health score in the range of >80, while subjects with spinal stenosis average in the 60 -80 range, while subjects suffering from moderate-severe osteoarthritis of the hip score in the 40-60 range.

[078] In one embodiment SOQOL scores equate to Quality of Life as follows:

[079] In other embodiments, the SOQOL scores can be compared to predetermined threshold scores for various QOL states (e.g. high, medium, poor) measured from a person or group of persons in the same or similar situation to the subject, for example those at the same or similar stage of life or those having the same or similar conditions as the subject, or even people who have had the same or similar medical procedures. For example, for a subject who has spinal surgery, the comparator scores to which the subject's SOQOL score is compared may be those for a group of people who have also had the same spinal surgery and can be used to determine whether the subject is progressing as well as, better than, or worse than the average of subjects who have experienced the same surgery.

[080] In another embodiment the group of persons is selected to provide a comparison to other subjects of the same age or to other subjects within a predetermined age group range. Accordingly, the methods can be used to determine whether the subject's well being is better than, worse than, or substantially similar to subjects of the same age or age group. The group of persons on which the comparator score is based may also be selected to allow for a comparison of a variety of other factors including but not limited to gender, health history, location, socioeconomic status, the type and duration of treatment being received, and the like. [081] In other embodiments the comparison of the subject's SOQOL score is not limited to only one comparator group, but rather the subject's scores can be compared to a plurality of different comparator scores obtained from different population groups, to provide a multidimensional analysis of the subject's treatment and overall QOL.

[082] The comparison of the subject's SOQOL score to the comparator score can involve a variety of different mathematical operations to provide information on the subject relative to the comparator group. For example, the comparison of the subject's SOQOL score to the comparator score involves calculating the difference between the SOQOL and comparator scores. The difference gives a measure of how much the subject deviates from the comparator group. The difference can also be evaluated by subtracting the SOQOL score from the standard score, or by taking the absolute values of the calculated difference.

[083] In another embodiment, a standard deviation of the comparator score is determined. The difference between the SOQOL score and the comparator score is then compared to the standard deviation to determine whether it is significant. For example, if the absolute value of the calculated difference is less than the absolute value of one standard deviation, then it may not be significant, whereas if the absolute value of the calculated difference is greater than the absolute value of one standard deviation, then it may be considered significant.

[084] In one embodiment the method comprises assigning a treatment regimen to the subject on the basis of the subject's SOQOL score or comparison of a SOQOL score to a comparator score. For example, if the subject's QOL is poor due to a low subjective score then a treatment regimen to improve the subject's mental health (for example) may be assigned to the subject. In another example, if the subject's QOL is poor due to a low objective score then a treatment regimen to improve the patent's mobility may be assigned to the patent. If both of the subject's subjective and objective scores are low then both regimens may be assigned, as appropriate.