Fall risk assessment system, its assessment method, and its assessment program

Abstract

To provide a new fall risk evaluation method capable of objectively and appropriately evaluating a fall risk.SOLUTION: A data measurement unit 4 measures gravity center movement of a subject in a standing state during a predetermined measurement period. This measurement period involves switching between a first measurement mode, which provides the subject with stimulation using a virtual light touch contact, and a second measurement mode, which provides the subject with less stimulation than that in the first measurement mode. On the basis of body movement data measured by the data measurement unit 4, an evaluation value calculation unit 6 calculates a balance age obtained by evaluating the subject's musculoskeletal system ability, a sense reaction score obtained by evaluating the subject's sensory system ability, and a standing position age obtained by evaluating the subject's ability with respect to both of the subject's musculoskeletal system and sensory system. A fall risk evaluation unit 7 evaluates the subject's fall risk on the basis of the balance age, the sense reaction score, and the standing position age.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a fall risk assessment system, an assessment method therefor, and an assessment program therefor, and more particularly to fall risk assessment using Virtual Light Touch Contact (VLTC). [Background technology]

[0002] Traditionally, a method called virtual light touch contact (VLTC) has been known. VLTC is a method that supports maintaining an upright posture by creating a virtual wall around a person and applying the reaction force of touching the wall as a vibration stimulus to the fingertips. VLTC virtually reproduces the phenomenon of light touch contact (LTC), in which body sway is reduced when a person lightly touches a wall or curtain.

[0003] Regarding VLTC, for example, Patent Document 1 discloses a posture stabilization aid that reproduces a simulated light touch contact in order to stabilize the user's posture. This aid has a housing that can be attached to a part of the user's body and a stimulation unit provided integrally with the housing. The stimulation unit provides stimulation to the area to which the housing is attached, in accordance with at least one of the following: the speed of the housing, the acceleration of the housing, the distance from a reference site to the housing, and the direction of the normal vector from the inner wall of a virtual sphere centered on the reference site toward the housing.

[0004] Furthermore, Patent Documents 2 and 3 disclose methods for calculating index values ​​using VLTC. In Patent Document 2, first, a fluctuation amount, which is a quantity related to the change in the subject's posture, is obtained. Next, the timing of switching the magnitude of the stimulus given to the sensory organ that receives stimuli related to at least one of the subject's visual, vestibular, and somatosensory stimuli is obtained. Then, an index value related to the subject's sense of balance is calculated based on the change in the fluctuation amount before and after the timing of switching the magnitude of the stimulus. On the other hand, in Patent Document 3, first, two or more fluctuation amounts indicating the movement of a standing subject are obtained. These fluctuation amounts include fluctuation amounts calculated using sensor measurements when a contact simulation unit, which is attached to a part of the standing subject's body and simulates contact of the attached part with an object, is simulating contact, and sensor measurements when the contact simulation unit is not simulating contact. Then, by applying the two or more fluctuation amounts to a predetermined function, an index value that indicates the stability of the subject's standing posture with a single scalar quantity is calculated. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6534010 [Patent Document 2] Patent No. 6569148 [Patent Document 3] Patent No. 6853532 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In recent years, the risk of falls has become an increasingly prominent issue for the elderly, and there is a need to introduce methods that can appropriately assess this risk. While there are subjective and objective assessments of fall risk, a major factor in falls is the discrepancy between subjective and objective assessments due to functional decline. Therefore, it is important to objectively visualize fall risks that are difficult to detect through subjective assessment, in other words, risks that individuals may not be aware of themselves. In this regard, the aforementioned prior literature 1-3 focused on achieving long-term balance control (LTC) without mechanical support, quantifying the subject's sense of balance, or quantifying the stability of the subject's standing posture, and did not consider the perspective of assessing the subject's fall risk.

[0007] This invention has been made in view of the above circumstances, and its purpose is to provide a novel method for evaluating the risk of falls that can objectively and appropriately assess the risk of falls of a subject. [Means for solving the problem]

[0008] To solve these problems, the first invention provides a fall risk assessment system comprising a data measurement unit, an evaluation value calculation unit, and a fall risk assessment unit, which evaluates the fall risk of a subject using virtual light touch contact. The data measurement unit measures the body sway of the subject while they are standing during a predetermined measurement period, which involves switching between a first measurement mode and a second measurement mode, and acquires body sway data. In the first measurement mode, the subject is stimulated by virtual light touch contact, and in the second measurement mode, the stimulation given to the subject is smaller than in the first measurement mode (including no stimulation). Based on the body sway data, the evaluation value calculation unit calculates a first evaluation value that evaluates the subject's musculoskeletal system ability, a second evaluation value that evaluates the subject's sensory system ability, and the subject's ability in the musculoskeletal and sensory systems. in The third evaluation value is calculated. The fall risk assessment unit evaluates the subject's fall risk based on the first evaluation value, the second evaluation value, and the third evaluation value.

[0009] The second invention provides a fall risk assessment method that evaluates the risk of a subject falling using virtual light touch contact, comprising the following steps. In the first step, body sway data indicating body sway while the subject is standing is acquired during a predetermined measurement period, which involves switching between a first measurement mode and a second measurement mode. In the first measurement mode, the subject is stimulated by virtual light touch contact, and in the second measurement mode, the stimulation given to the subject is smaller than in the first measurement mode (including no stimulation). In the second step, based on the body sway data, a first evaluation value that evaluates the subject's musculoskeletal system ability and a second evaluation value that evaluates the subject's sensory system ability are obtained, and the subject's abilities are evaluated for the musculoskeletal system and sensory system. in The third evaluation value is calculated. In the third step, the subject's risk of falling is assessed based on the first evaluation value, the second evaluation value, and the third evaluation value.

[0010] The third invention provides a fall risk assessment program that evaluates the risk of a subject falling using body sway data showing the subject's body sway while standing, during a predetermined measurement time involving switching between a first measurement mode and a second measurement mode. This program causes a computer to perform the following steps: In the first step, based on the body sway data, a first evaluation value is obtained that evaluates the subject's musculoskeletal system ability, a second evaluation value is obtained that evaluates the subject's sensory system ability, and the subject's abilities are evaluated for the musculoskeletal system and sensory system in The third evaluation value is calculated. In the second step, the subject's risk of falling is assessed based on the first evaluation value, the second evaluation value, and the third evaluation value.

[0011] Hereinafter, in the first to third inventions, the first evaluation value may be calculated based on a first absolute sum of the values ​​of multiple evaluation indices relating to the subject's body sway, calculated based on body sway data; the second evaluation value may be calculated based on a second absolute sum of the values ​​of multiple ratio indices indicating the proportion of frequency components in which specific sensations related to standing contribute to the control of standing, calculated by performing frequency analysis on the body sway data; and the third evaluation value may be calculated based on a weighted sum of the first absolute sum and the second absolute sum.

[0012] In the first to third inventions, the first to third evaluation values ​​may be calculated for each of the first and second measurement conditions, where the position of the subject's soles is different. In this case, it is preferable to comprehensively evaluate the subject's risk of falling based on the first to third evaluation values ​​calculated under the first measurement condition and the first to third evaluation values ​​calculated under the second measurement condition.

[0013] In the first to third inventions, a first score obtained by scoring the first evaluation value, a second score obtained by scoring the second evaluation value, and a third score obtained by scoring the third evaluation value may be identified by referring to a pre-prepared score conversion table. In this case, it is preferable to calculate an evaluation score that scores the subject's fall risk by summing the first to third scores. Alternatively, by referring to the score conversion table, The subjects' musculoskeletal capabilities were evaluated, and the quality of their physical balance was indexed. Balance age and 、 A fourth score, which is a score representing the difference between the subject's actual age and the given age, The subjects' abilities were evaluated in terms of their musculoskeletal and sensory systems, and their risk of falling was expressed. Standing age and 、 A fifth score may be identified, which is a score representing the difference between the subject's actual age and the given age. In this case, it is preferable to calculate the evaluation score by adding the fourth and fifth scores in addition to the first to third scores. [Effects of the Invention]

[0014] According to the present invention, by comprehensively evaluating a first evaluation value for evaluating the skeletal system ability of a subject, a second evaluation value for evaluating the sensory system ability of the subject, and a third evaluation value for evaluating the ability of the subject in both the skeletal system and the sensory system, it is possible to objectively and appropriately evaluate the risk of falling.

Brief Description of the Drawings

[0015] [Figure 1] Configuration diagram of the fall risk assessment system [Figure 2] Flowchart of fall risk assessment [Figure 3] Explanation diagram of the measurement period [Figure 4] Graph showing the relationship between the sum of absolute values and age [Figure 5] Graph showing the relationship between the weighted sum and age [Figure 6] Explanation diagram of the fall risk index under a single measurement condition [Figure 7] Explanation diagram of the fall risk index under multiple measurement conditions

Mode for Carrying Out the Invention

[0016] FIG. 1 is a configuration diagram of the fall risk assessment system according to the present embodiment. The fall risk assessment system 1 evaluates the fall risk of a subject using virtual light touch contact (hereinafter referred to as "VLTC"). The fall risk assessment system 1 is specialized for objective evaluation, which is one of the evaluation factors of the fall risk, and comprehensively measures the responses to internal factors (such as the decline of sensory functions such as muscle strength, balance function, vision, and vestibular sense associated with aging changes) and external factors (external disturbance stimuli) among the risk factors that cause falls. Therefore, psychological factors, subjective evaluations of one's own internal factors, and their differences are not the objects of evaluation. In this specification, "fall risk" is defined as an objective quantitative evaluation related to the internal factors related to falls evaluated by the fall risk assessment system 1 and the responses to external disturbances.

[0017] The fall risk assessment system 1 mainly consists of a control unit 2, a vibration-type acceleration sensor 3, a data measurement unit 4, a data storage unit 5, an evaluation value calculation unit 6, and a fall risk assessment unit 7. The control unit 2 and the vibration-type acceleration sensor 3 are devices for realizing VLTC, and they are connected via cables. The control unit 2 has a wristwatch shape and is worn on the subject's dominant wrist. The vibration-type acceleration sensor 3 is worn as a fingertip cuff on a specific body part of the subject, specifically on the index finger of the subject's dominant hand. Based on the detection signal from the vibration-type acceleration sensor 3, the control unit 2 identifies the momentum (physical change) of the index finger, vibrates the vibration-type acceleration sensor 3 in accordance with the sign reversal of the velocity vector, and applies a vibration stimulus to the subject's fingertip as a reaction force (virtual reaction force) of touching a virtual wall.

[0018] Furthermore, the stimuli applied to the subject are not limited to vibrational stimulation from the vibration-type acceleration sensor 3, but may also include pressure stimulation, sound stimulation, temperature stimulation, electrical stimulation, etc. In addition to the above examples, the method for realizing VLTC can also be disclosed in the aforementioned Patent Document 1, by imaging a subject with a housing equipped with a vibrator attached to their fingertip using a motion capture device (imaging unit), and recognizing the position of the housing using image analysis technology.

[0019] The data measurement unit 4 measures the body sway (sway of the entire body, not just a part of it) of a standing subject and acquires body sway data. In this embodiment, a posturograph is used as the data measurement unit 4. In this case, the subject, who is fitted with the control unit 2 and vibration-type acceleration sensor 3, stands on the posturograph. During the measurement period in which the measurement is performed, the body sway data output from the posturograph is sequentially stored in the data storage unit 5. The data stored in the data storage unit 5 is used for processing described later. Note that the data measurement unit 4 is not limited to a posturograph; it may also be a camera. In this case, body sway is calculated and measured based on the subject's movements captured by the camera. It is also possible to use an acceleration sensor as the data measurement unit 4.

[0020] The evaluation value calculation unit 6 calculates three evaluation values—balance age, sensory reaction score, and standing age—based on the body sway data read from the data storage unit 5. Here, "balance age" is an index that evaluates and quantifies the subject's musculoskeletal ability. A higher balance age indicates poorer body balance. "Sensory reaction score" is an index that evaluates and quantifies the subject's sensory ability. This sensory reaction score evaluates body sway caused by visual and somatosensory factors on a scale of 100 points, with a lower score indicating a decline in the sensory system. Furthermore, "standing age" evaluates the subject's ability in both the musculoskeletal and sensory systems and expresses the subject's risk of falling as standing age.

[0021] The fall risk assessment unit 7 comprehensively assesses the subject's fall risk based on at least the balance age, sensory reaction score, and standing age calculated by the assessment value calculation unit 6, and outputs the assessment result as a fall risk index (F-RiSc). In addition to the three assessment values ​​mentioned above, the difference between balance age and the subject's actual age, and the difference between standing age and the subject's actual age may also be considered when calculating this index.

[0022] Next, the procedure for assessing fall risk will be explained with reference to Figure 2. First, in step S1, devices (control unit 2 and vibration-type acceleration sensor 3) are attached to designated body parts of the subject.

[0023] In step S2, prior to the start of the measurement, the subject prepares for the measurement. Specifically, first, the subject lightly shakes their dominant hand from the wrist as if touching a wall. This generates vibration in the vibration-type acceleration sensor 3. The subject shakes their hand in a relaxed posture, as if walking along a wall. Next, the subject removes their shoes and stands on the data measurement unit 4 (center of gravity sway meter). The position of the soles of the feet in the standing position can be selected from either a closed-leg standing position with both legs together or a semi-tandem standing position with both feet one behind the other, depending on the purpose of the measurement and the subject's condition. Furthermore, the measurement may be performed not only under a single measurement condition (e.g., closed-leg condition), but also under multiple measurement conditions with different positions of the subject's soles (e.g., both closed-leg and semi-tandem conditions).

[0024] In step S3, after confirming that there are no problems with the subject's posture or arm swing while standing with eyes closed, the measurement is performed for a predetermined measurement period (e.g., 60 seconds). During the measurement, the subject continues to shake their wrists. At the same time, they close their eyes, do not make any sounds, and focus their attention on the vibration of their fingertips. In step S4, the body sway data acquired chronologically by the data measurement unit 4 is sequentially stored in the data storage unit 5. Then, it is determined whether or not the measurement period has elapsed (step S5). As a result, the measurement continues in a loop of steps S3 to S5 until the measurement period has elapsed, at which point the measurement ends and the process proceeds to step S6.

[0025] Figure 3 is an explanatory diagram of the measurement period. This measurement period has four measurement modes A to D, and involves switching between adjacent measurement modes. Measurement modes A and C are modes in which vibration stimuli are applied to the subject by virtual light touch contact (hereinafter referred to as "vibration modes"). On the other hand, measurement modes B and D are modes in which the stimulus applied to the subject is smaller than that of measurement modes A and C, and in this embodiment, "no stimulus" is used as an example (hereinafter referred to as "non-vibration modes"). In vibration modes A and B, vibration stimuli are applied to the subject's index finger (vibration-type acceleration sensor 3) according to the momentum (amount of physical change in space and time), more specifically, when the sign of the velocity vector is reversed. In non-vibration modes C and D, vibration stimuli are not applied to the subject's index finger regardless of its position. By switching between these modes, it becomes possible to apply disturbance stimuli to the subject and quantitatively measure and evaluate the change in the standing state accompanying the change in virtual reaction force. In this embodiment, the measurement period is divided into two sets of measurement modes A to D, but it is sufficient to have at least one set of measurement modes A and B.

[0026] In step S6, the "balance age," an evaluation value that assesses the subject's musculoskeletal ability, is calculated. Specifically, first, k (k≧2) evaluation indices are calculated using the body sway data read from the data storage unit 5. In this embodiment, as an example, k=28 evaluation indices are used, broadly categorized into "distance," "area," "velocity," and "vector variables."

[0027] Here, "distance" is an index used to evaluate the length of a line representing the trajectory of body sway in the system. A larger value indicates greater body instability. There are six types of "distance": single trajectory length, effective value, effective value in the x-direction, effective value in the y-direction, maximum amplitude in the x-direction, and maximum amplitude in the y-direction. "Area" is an index that represents the instability of body sway. It is known that a significant difference is observed between those who have experienced falls and those who have not, when static standing or when horizontal and anterior-posterior vibration stimuli are applied to a footing. There are five types of "area": ​​effective value area, rectangular area, perimeter area, unit area trajectory length, and standard deviation area. "Velocity" is known to indicate that a larger value indicates greater postural instability, and it is used to evaluate postural instability in a standing position. There are nine types of "velocity": the average x-direction sway velocity, the average y-direction sway velocity, the effective value of body sway velocity, the effective value of x-direction body sway velocity, the effective value of y-direction body sway velocity, the maximum x-direction sway velocity, the maximum y-direction sway velocity, the standard deviation of x-direction sway velocity, and the standard deviation of y-direction sway velocity. In addition, "vector variables" are indices used in examinations for vestibular disorders, etc. There are eight types of "vector variables": the average vector length of sway in direction A, the average vector length of sway in direction B, the average vector length of sway in direction C, the average vector length of sway in direction D, the average vector length of sway in direction E, the average vector length of sway in direction F, the average vector length of sway in direction G, and the average vector length of sway in direction H.

[0028] Furthermore, k evaluation indices are calculated for each of the n (n≧2) data intervals. In this embodiment, as an example, n=3, and the data intervals are defined as (1) the entire measurement period (60 seconds), (2) the combined period of the two non-vibration modes B and D (30 seconds), and (3) periods a to d, which include the periods a and b before and after the timing of switching from vibration mode A to non-vibration mode B, and the periods c and d before and after the timing of switching from vibration mode C to non-vibration mode D. Therefore, when calculating balance age, a total of k×n=N (k=28, N=84 if n=3) evaluation indices are calculated. Regarding (3) above, after calculation, the change in body sway after the vibration has stopped is evaluated by calculating "ba" and "d-c" for each index.

[0029] Next, the calculated evaluation index d l Regarding this, as shown in the formula below, the mean value μ of the reference group data (data set measured so far), such as the young healthy control group. l , standard deviation δ l Standardization is performed using the standardized evaluation index (hereinafter referred to as "Standardized Value I") l ) is calculated.

[0030]

number

[0031] Next, the standardized value I l The sum of absolute values, SUM(I), is calculated based on the following formula.

[0032]

number

[0033] Then, the balance age is calculated by inputting the absolute sum SUM(I) into a pre-built balance age estimation model using a large amount of data measured in the past. The relationship between the absolute sum SUM(I) and age x is expressed by a linear function as shown in the equation below.

[0034]

number

[0035] This inverse function is expressed by the following equation, and by using this as a balance age estimation model, it becomes possible to estimate the balance age from the sum of absolute values ​​SUM(I).

[0036]

number

[0037] Figure 4 is a graph showing the relationship between the absolute value sum SUM(I) of actual subject data and age x. In this example, it can be modeled with α = 1.599 and β = 145.4. Thus, the balance age is calculated as an index obtained by fitting the amount of spatial and temporal body sway (center of gravity change) of the subject to a predetermined model.

[0038] In step S7, a "sensory response score", which is an evaluation value for evaluating the sensory ability of the subject, is calculated. Frequency analysis is performed on n' (l = 0 ··· n', n' ≥ 2) data intervals of the body sway data read from the data storage unit 5, and the sensory response score is calculated by evaluating the ratio (including its change) in a specific frequency band. Specifically, first, frequency analysis using the Welch method is applied to the body sway data in the sagittal plane direction in the l-th data interval to obtain a power spectrum G(ω). Then, for each frequency band where the three senses (vision, vestibular sense, and somatosensory sense) related to standing contribute to the control of the body, a ratio index S i,l (i ∈ {e, s}, e: vision, s: somatosensory sense) is calculated. In this embodiment, since the subject is given closed-eye and vibration stimulation to the fingertips (somatosensory stimulation) and no stimulation to the vestibular system, it is considered that the vestibular sense does not have a significant influence compared to the other two sensory systems. Therefore, based on the following formula, the ratios of vision and somatosensory sense are evaluated. Here, S e,l is the vision system, S s,l is the ratio of the sway derived from the somatosensory sense to the whole in the l-th data interval.

[0039]

Equation

[0040] Also, the ratio index S i,lThis is calculated for each of the n'(n'n≧2) data intervals. In this embodiment, as an example, n'=2, and the data intervals are (1) the total period of the two vibration modes A and C (30 seconds) as shown in Figure 3, and (2) periods a to d that include the periods a and b before and after the timing of switching from vibration mode A to non-vibration mode B, and the periods c and d before and after the timing of switching from vibration mode C to non-vibration mode D. In the data interval of (1) above, 28 proportion indices are calculated, similar to the balance age described above. In the data interval of (2) above, 28 proportion indices are calculated for each of the periods a to d, and after this calculation, the change in body sway after the vibration has stopped is evaluated by calculating "ba" and "dc" for each proportion indice.

[0041] Next, the calculated proportion index S i,l Regarding this, as shown in the formula below, the mean value of reference group data (data sets measured so far), such as the young healthy control group. i,l , standard deviation δ i,l Standardization is performed using the standardized evaluation index (hereinafter referred to as "Standardized Value SI"). i,l ) is calculated.

[0042]

number

[0043] Next, the standardized value SI i,l The sum of absolute values, SUM(SI), is calculated based on the following formula.

[0044]

number

[0045] Then, the sensory response score is calculated by inputting the sum of absolute values ​​(SUM(SI)) into the following sensory response score estimation model, which has been pre-built using a large amount of data measured in the past. In this model, the scores are calculated on a maximum of 100 points, so that the average score in the healthy subject database is 50 points. In this way, the sensory response score is calculated as a score that evaluates the frequency spectrum of the body sway (center of gravity change) period before and after the condition transition from vibration present to vibration absent.

[0046]

number

[0047] In step S8, the "standing age," an evaluation value that assesses the subject's abilities in both the musculoskeletal and sensory systems, is calculated. Specifically, first, as shown in the formula below, the weighted sum WSUM is calculated from the sum of absolute values ​​SUM(I) calculated in the balance age calculation process and the sum of absolute values ​​SUM(SI) calculated in the sensory reaction score calculation process.

[0048]

number

[0049] Then, by inputting the weighted sum WSUM into a pre-built standing age estimation model using a large amount of data measured in the past, the standing age is calculated. The relationship between the weighted sum WSUM and age x is expressed by a linear function as shown in the equation below.

[0050]

number

[0051] This inverse function is expressed by the following equation, and by using this as a standing age estimation model, it becomes possible to estimate standing age from the weighted sum WSUM.

[0052]

number

[0053] Figure 5 shows the actual subject data w b =w s This graph shows the relationship between the weighted sum WSUM and age x when α = 1, and it can be modeled with α = 2.246 and β = 161.9.

[0054] In step S9, the subject's fall risk is comprehensively evaluated based on balance age, sensory reaction score, and standing age, and a fall risk index (F-RiSc) is output as a result of this evaluation.

[0055] Figure 6 is an explanatory diagram of the fall risk index when measured under a single measurement condition (e.g., with legs together). As shown in the figure, there are six evaluation items: "sensory reaction score," "balance age," "standing age," "balance age - actual age," "standing age - actual age," and "fall during measurement." For each evaluation item, the correspondence between the evaluation condition and the fall risk score (a higher value indicates a higher risk of falling) is described in a score conversion table. The "balance age," "sensory reaction score," and "standing age" calculated in steps S6 to S8 above are scored according to the evaluation conditions described in the score conversion table. For example, if the "balance age" is 56 years old, the evaluation condition becomes "51 to 70 years old," and a "fall risk score" of 2 points is assigned. In addition, in order to reflect the subject's actual age in the evaluation results, "balance age - actual age" and "standing age - actual age" are also scored by referring to the score conversion table. Furthermore, "fall during measurement" refers to situations such as when the subject falls from the data measurement unit 4. If this occurs, a very high score is assigned to it, representing the highest risk level. "Total value (a)" is the sum of the scores for these evaluation items, and this becomes the final fall risk index. Then, by referring to the correspondence relationship (risk level evaluation table) shown in the right column of the same figure, the fall risk level (5 levels) corresponding to "Total value (a)" is determined.

[0056] Figure 7 is an explanatory diagram of the fall risk index when measured under multiple measurement conditions (e.g., closed-leg condition and semi-tandem condition). When measured under the closed-leg condition, each evaluation item is scored, and these scores are summed up to obtain the "Total Value (a)". Similarly, when measured under the semi-tandem condition, each evaluation item is scored, and these scores are summed up to obtain the "Total Value (b)". The final fall risk index is calculated by summing "Total Value (a)" and "Total Value (b)", i.e., "Total Value (c)". Then, by referring to the correspondence relationship (risk level evaluation table) shown in the right column of the figure, the fall risk level (5 levels) corresponding to "Total Value (c)" is determined.

[0057] Thus, according to this embodiment, the subject's musculoskeletal ability is evaluated as balance age, the subject's sensory ability is evaluated as sensory reaction score, and the subject's ability is evaluated in terms of both the musculoskeletal and sensory systems as standing age. By comprehensively evaluating these, the subject's risk of falling can be objectively and appropriately assessed.

[0058] Furthermore, according to this embodiment, by performing measurements multiple times while changing the measurement conditions, such as with legs together and with semi-tandem conditions, and integrating the multiple evaluation values ​​obtained, the subject's risk of falling can be evaluated with greater accuracy. In addition, by taking into account the difference between balance age / standing age and the subject's actual age, the subject's actual age can be reflected in the evaluation of their risk of falling.

[0059] In the above-described embodiment, the evaluation value calculation unit 6 and the fall risk evaluation unit 7 shown in Figure 1 may be implemented by a computer. In this case, the present invention can also be considered as a computer program that causes the computer to execute the processes of steps S6 to S9 shown in Figure 2. In this case, the memory unit of the computer stores the score conversion table described above, and the evaluation items are scored by referring to this table. [Explanation of Symbols]

[0060] 1. Fall Risk Assessment System 2 Control Unit 3. Vibration-type acceleration sensor 4. Data Measurement Unit 5. Data Storage Unit 6. Evaluation Value Calculation Unit 7. Fall Risk Assessment Department

Claims

1. In a fall risk assessment system that uses virtual light touch contact to evaluate the risk of falls in subjects, A data measurement unit that measures the body sway of a subject while they are standing and acquires body sway data during a predetermined measurement period, which involves switching between a first measurement mode in which the subject is stimulated by the virtual light touch contact and a second measurement mode in which the subject is stimulated less than in the first measurement mode. Based on the aforementioned body sway data, an evaluation value calculation unit calculates a first evaluation value that evaluates the subject's musculoskeletal ability, a second evaluation value that evaluates the subject's sensory ability, and a third evaluation value that evaluates the subject's ability in terms of both the musculoskeletal and sensory systems. A fall risk assessment unit that assesses the subject's fall risk based on the first assessment value, the second assessment value, and the third assessment value. A fall risk assessment system characterized by having the following features.

2. The aforementioned evaluation value calculation unit, Based on the aforementioned body sway data, a plurality of evaluation indices related to the subject's body sway are calculated, and based on the first sum of the absolute values ​​of the plurality of evaluation indices, the first evaluation value is calculated. Frequency analysis of the aforementioned body sway data is performed to calculate multiple proportion indices that show the proportion of frequency components in which specific sensations related to standing contribute to the control of standing, and a second evaluation value is calculated based on the second sum of absolute values ​​of these multiple proportion indices. The fall risk assessment system according to claim 1, characterized in that it calculates the third evaluation value based on the weighted sum of the first absolute value sum and the second absolute value sum.

3. The evaluation value calculation unit calculates the first to third evaluation values ​​for each of the first and second measurement conditions, where the position of the subject's sole is different. The fall risk assessment system according to claim 1 or 2, characterized in that the fall risk assessment unit comprehensively assesses the subject's fall risk based on the first to third evaluation values ​​calculated under the first measurement conditions and the first to third evaluation values ​​calculated under the second measurement conditions.

4. The fall risk assessment system according to any one of claims 1 to 3, characterized in that the fall risk assessment unit refers to a pre-prepared score conversion table to identify a first score obtained by scoring the first evaluation value, a second score obtained by scoring the second evaluation value, and a third score obtained by scoring the third evaluation value, and calculates an evaluation score obtained by scoring the subject's fall risk by summing the first to third scores.

5. The evaluation value calculation unit refers to the score conversion table to evaluate the subject's musculoskeletal ability and identifies a fourth score which is the difference between the balance age, which is an index of the subject's physical balance, and the subject's actual age, and a fifth score which is the difference between the standing age, which is an index of the subject's risk of falling, and the subject's actual age, and evaluates the subject's ability in the musculoskeletal and sensory systems. The fall risk assessment system according to claim 4, characterized in that the fall risk assessment unit calculates the assessment score by adding the fourth and fifth scores in addition to the first to third scores.

6. In a fall risk assessment method that uses virtual light touch contact to evaluate the risk of a subject falling, A first step involves acquiring body sway data indicating the body sway of the subject while standing, during a predetermined measurement period which involves switching between a first measurement mode in which the subject is stimulated by the virtual light touch contact and a second measurement mode in which the stimulation given to the subject is less than that of the first measurement mode. A second step involves calculating a first evaluation value that assesses the subject's musculoskeletal ability based on the aforementioned body sway data, a second evaluation value that assesses the subject's sensory ability, and a third evaluation value that assesses the subject's ability in terms of both the musculoskeletal and sensory systems. A third step in which the subject's risk of falling is evaluated based on the first evaluation value, the second evaluation value, and the third evaluation value. A method for assessing the risk of falling, characterized by having the following features.

7. The second step described above is: The steps include: calculating multiple evaluation indices related to the subject's body sway based on the aforementioned body sway data, and calculating the first evaluation value based on the first sum of absolute values ​​of the aforementioned multiple evaluation indices; The steps include: performing frequency analysis on the aforementioned body sway data to calculate multiple proportion indices that show the proportion of frequency components in which specific sensations related to standing contribute to the control of standing; and calculating the second evaluation value based on the second sum of absolute values ​​of the multiple proportion indices; The steps include: calculating the third evaluation value based on the weighted sum of the first absolute value sum and the second absolute value sum; A fall risk assessment method according to claim 6, characterized by having the following features.

8. The first and second steps are performed under first and second measurement conditions, respectively, where the position of the subject's soles is different. The fall risk assessment method according to 6 or 7, characterized in that the third step comprehensively evaluates the subject's fall risk based on the first to third evaluation values ​​calculated under the first measurement conditions and the first to third evaluation values ​​calculated under the second measurement conditions.

9. Step 3 above is, A fourth step involves referring to a pre-prepared score conversion table to identify a first score obtained by scoring the first evaluation value, a second score obtained by scoring the second evaluation value, and a third score obtained by scoring the third evaluation value. A fifth step involves calculating an evaluation score that scores the subject's risk of falling by summing the first to third scores mentioned above. A fall risk assessment method according to any one of 6 to 8, characterized by having the following features.

10. The fourth step involves referring to the score conversion table to identify a fourth score, which is the difference between the balance age, an index of the subject's physical balance, and the subject's actual age, and a fifth score, which is the difference between the standing age, an index of the subject's physical balance, and the subject's actual age, and an index of the difference between the standing age, an index of the subject's risk of falling, and the subject's ability, which is evaluated in terms of the musculoskeletal and sensory systems. The fall risk assessment method according to claim 9, characterized in that the fifth step calculates the evaluation score by adding the fourth and fifth scores in addition to the first to third scores.

11. In a fall risk assessment program that evaluates the risk of a subject falling using body sway data indicating the subject's body sway while standing, during a predetermined measurement period which involves switching between a first measurement mode in which a subject is stimulated using virtual light touch contact and a second measurement mode in which the subject is stimulated less than in the first measurement mode, The first step involves calculating a first evaluation value that assesses the subject's musculoskeletal ability based on the aforementioned body sway data, a second evaluation value that assesses the subject's sensory ability, and a third evaluation value that assesses the subject's ability in terms of both the musculoskeletal and sensory systems. A second step of evaluating the subject's risk of falling based on the first evaluation value, the second evaluation value, and the third evaluation value. A fall risk assessment program characterized by causing a computer to perform a process that includes the following.

12. The first step described above is, The steps include: calculating multiple evaluation indices related to the subject's body sway based on the aforementioned body sway data, and calculating the first evaluation value based on the first sum of absolute values ​​of the aforementioned multiple evaluation indices; The steps include: performing frequency analysis on the aforementioned body sway data to calculate multiple proportion indices that show the proportion of frequency components in which specific sensations related to standing contribute to the control of standing; and calculating the second evaluation value based on the second sum of absolute values ​​of the multiple proportion indices; The steps include: calculating the third evaluation value based on the weighted sum of the first absolute value sum and the second absolute value sum; A fall risk assessment program according to claim 11, characterized by having the following features.

13. The first step is performed in each of the first and second measurement conditions, where the position of the subject's sole is different. The fall risk assessment program according to claim 11 or 12, characterized in that the second step comprehensively evaluates the subject's fall risk based on the first to third evaluation values ​​calculated under the first measurement conditions and the first to third evaluation values ​​calculated under the second measurement conditions.

14. The second step described above is: A third step involves referring to a pre-prepared score conversion table to identify a first score obtained by scoring the first evaluation value, a second score obtained by scoring the second evaluation value, and a third score obtained by scoring the third evaluation value. A fourth step involves calculating an evaluation score that scores the subject's risk of falling by summing the first to third scores mentioned above. A fall risk assessment program according to any one of claims 11 to 13, characterized by having the following features.

15. The second step involves referring to the score conversion table to identify a fourth score which is the difference between the subject's musculoskeletal ability, the balance age which is an index of the subject's physical balance, and the subject's actual age, and a fifth score which is the difference between the subject's standing age which is an index of the subject's ability in the musculoskeletal and sensory systems, and the subject's risk of falling, and the subject's actual age. The fall risk assessment program according to 14, characterized in that the third step calculates the evaluation score by adding the fourth and fifth scores in addition to the first to third scores.

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