3.1. System Rating Criteria
Dealing with technological solutions aimed at enabling the user (i.e., the patient) to self-manage the collection of his health data, for their analysis and evaluation by a remote medical operator, different rating criteria shall be defined. Besides a technical evaluation, based on the features provided by each system, that can be tested and rated according to quantitative figures, it is necessary to provide also a user-related evaluation, that can be further itemized into a patient's perspective and an operator's perspective.
3.1.1. Technical Rating Issues A telemedicine system is typically obtained by integrating different technologies and subsystems, each of them covering specific functionalities needed to provide the requested services. In this case, the focus is on remote monitoring of health-related parameters, that may help in preventing or limiting the impact of heart failures and related symptoms. According to the short description of the systems under test, provided in the previous Section, it is possible to identify some common blocks composing the architectures herein considered as follows:
- client side: the set of biomedical sensors used to monitor the patient's parameters;
- client side: the central unit acting as a gateway among the patient's premise and the remote health center;
- server side: a remote platform including a data repository and a software interface to access it and to perform the requested data analyses.
Each of these blocks may provide specific functionalities, with different degrees of performance. As already stated, the
set of biomedical sensors used by
System A,
B, and
C is the same, apart from the stethoscope device, that is not supported by
System C. Each sensor is available in different flavors, that is, with a wired or wireless connection to the central unit, and the selection of the specific sensor to use shall be based on technical issues (the possibility of integrating or interfacing the sensor to the client central unit), but also on usability-related aspects. With the aim of defining general rating criteria, that can fit almost any sensor device, and due to the target users the system should support (elderly or partially disabled patients), it is expected to assign higher scores to those solutions that integrate wireless sensors, instead of wired ones; sensors that are able to provide a visual or acoustic feedback about the proper data acquisition and transfer to the central unit; sensors that notify their battery power level; sensors that do not require an initial configuration by the user, or at least, that do minimize the number of configuration steps necessary before collecting the desired data. Assuming a rating parameter defined as
s and a scale from 5 (highest rate) to 1 (lowest rate), the rating criteria for each sensor the system is equipped with, may be defined according to . By scoring each device in the set of sensors, it is possible to get a global score for the system sensor set, named
S, so that
where
N is the number of sensors in the set,
M is the number of sensor rating issues (
M = 4 in our model), and
sij is the score assigned to each
ith rating issue, for each
jth sensor in the set. The
S parameter is not normalized, in order to properly account for the different number of sensors each telemedicine system may provide.
| Table 2Technical rating criteria: sensors. |
About the central unit at the client side, that is in charge of collecting the sensors' data and interfacing the patient to the remote healthcare center, it is possible to identify a number of features for its technical rating. The features are selected to be applicable to different solutions, but, at the same time, they are enough detailed to allow for a meaningful rating process. According to the amount and nature of the data the unit has to manage and transfer to the remote center, and one of its basic feature is the network interface the unit is equipped with. Assuming that an “ideal” solution should enable the joint transmission of audio, video, and data streams, corresponding to the information flows that take place during a remote, but “live” medical check, where a doctor is able to interact with the patient in real time, the highest score should be assigned to systems supporting broadband network connections, and the lowest score should be given to systems provided with narrowband interfaces. On the other hand, assuming the technological platform may be decomposed into “atomic” services (e.g., the transmission of the blood pressure data only, or the transmission of the ECG data only) a narrowband connection could be also accepted, but this would limit the potential benefits obtainable from the platform itself, as a whole.
The flow of information, during a data collection session with no active video communication, is basically asymmetric, with the client side mainly uploading data towards the remote repository. However, the amount of data is limited, so that we assume that symmetric or asymmetric connections may be rated the same score. Besides that, it is important also to check if the network interface supported is a wired or a wireless one. This scoring criterion, however, also depends on the target users the system is designed for. Limiting the present discussion to systems designed for the elderly or partially disabled people, it is assumed to provide higher scores to wireless solutions, because they result less invasive with respect to the patient's home environment and do not require any cabling operations to be set up. To this aim, we assume that the initial set up of the client central unit wireless connection is provided by technicians involved in the service delivery. The performance of the data transfer process may be optimized if some audio and video compression techniques are applied: the client central unit should be designed in order to trade off compression efficiency and audio/video quality. Highest score will be given to systems providing compressed video at CIF resolution (355 × 288 pixels) as a minimum and compressed audio at a tunable quality (the highest one required when transmitting the patient's auscultation audio signals). Another feature that may be critical to the effective use of the telemedicine system is the possibility offered by the client central unit of automatically switching between synchronous and asynchronous data management: the former enables a real time data transmission to the remote center, and the latter allows for a temporary storage of the collected data within the unit itself, and a delayed transmission, as soon as the network connection becomes available. This feature is a basic one if the central unit adopts a wireless network interface, in order to avoid data losses due to temporary connection outages. In order to minimize the user's actions on the system, to configure the central unit or to update its software components, it is expected to assign higher scores to solutions supporting a remote client management, that provides automatic software updates and configurations. Finally, the evaluation will assess positively the solutions ensuring data privacy and security, by means of protected data connections established between the patient and the remote healthcare center. The technical rating criteria defined for the client central unit are summarized in . Again, it is possible to define a central unit global score, named CU, as
where
K is the number of rating criteria (
K = 7, in our model), and cu
k is the score assigned to each criterion.
| Table 3Technical rating criteria: client central unit. |
The
server side evaluation of the telemedicine system typically involves two basic components: a data repository, where the data collected by the remote patients are stored, and a software interface, that allows the operators to access the data and to perform the requested evaluation. About the data repository, the recent evolutions in the field of cloud-based data management [
12,
13] suggest the adoption of the SaaS (Software as a Service) paradigm, instead of the more traditional PaaS (Platform as a Service) one. The former ensures higher reliability, because data are not physically located in a machine but are spread across a cloud of nodes, cooperating towards the provision of a specific service. As a consequence, once defined a rating parameter rp referred to the remote platform composing elements, it is assumed to assign the highest score (rp = 5) to a telemedicine solution that relies on a SaaS paradigm, a medium score (rp = 3) to a solution adopting a PaaS approach, and the lowest score (rp = 1) to solutions requiring a dedicated local storage server.
Given the specific nature of the data collected by the remote clients and transferred to the repository, a number of security services shall be ensured for any service provisioned through the remote platform, such as data integrity protection, by the adoption of secure transmission protocols and certificates between the client gateway and the remote platform; separation of legally valued and identity-related data; safe management of the remote platform within the data center adopted (backup policies, continuous monitoring, and system access control); access control and tracking, with specific focus on the personal patients' data; authenticated and controlled accounts; security policies for passwords management. Different scores may be assigned to each issue, according to the specific security solution adopted, its strength and robustness.
About the technical features related to the software interface used by the operators to access the set of data collected by each patient, highest rate is assigned to solutions providing a web-enabled access, so that the operator may perform the requested evaluation irrespective of his physical location (mobility support), simply by resorting to a web browsing application. Software interfaces designed for multimodal and multichannel access (i.e., by a PC or a mobile device) are preferable to solutions requiring specific plugins or software components to be installed, or executed on specific OSs. Finally, the implementation of security services for access authentication and tracking is another issue, ranked according to the robustness of the specific solution adopted. The set of ranking criteria defined for the remote platform is summarized in . As previously done, a global remote platform score, named RP, may be defined as
where
R is the number of ranking criteria adopted (
R = 10 in our model), and rp
z is the score assigned to each ranking issue.
| Table 4Technical rating criteria: remote platform. |
Once the technical rating criteria for each subsystem have been identified, and the corresponding rating parameter defined, it is possible to derive a global system rating parameter, referred to the technical features of the telemedicine solution as a whole, as
where TTP is the
technical telemedicine system parameter,
α,
β, and
γ are weighting factors used to differentiate the impact of each subsystem on the global technical rating of the telemedicine solution. We assume to have {
α,
β,
γ}
![[set membership]](/corehtml/pmc/pmcents/x2208.gif)
[0; 1]. The value assigned to each weighting factor during the assessment process depends on the expected or estimated impact of each sub-system on the effectiveness, reliability, and performance of the whole system. As an example, if the telemedicine solution is expected to provide a second-opinion service among health operators, the weighting factors will satisfy the following condition:
α <
β
γ. On the other hand, a telemedicine system designed to provide remote healthcare services in underserved areas (such as rural areas) will feature a different condition, like:
α
β and {
α,
β} >
γ. The specific value assigned to each weighting factor is consequently related to the service model implemented through the telemedicine system.
3.1.2. User-Related Rating Issues: Patient Side The definition of suitable rating criteria from a patient's perspective is a critical point to the proper evaluation of the global telemedicine solution. As a matter of fact, it is not possible to completely generalize the definition of such criteria, as they are strictly dependent on the target users the system is designed for.
This work is focused on elderly or partially disabled people, so it is mandatory to account for their specific needs, related to the variety of physical or cognitive impairments that may characterize the patient's condition. In the case of elderly patients, several rating criteria may be defined to assess the telemedicine system from a usability perspective. Among them, we consider the ergonomics of the medical devices the patient should use to collect his health data (not too small dimensions, effective visual or acoustic signalling, and easy switch on/off); suitably formatted and delivered instructions to guide the user; easy and quick switch on/off of the client central unit; clearness and easiness-of-use of the Graphic User Interface (GUI) the client central unit is equipped with; reliability of the application used to manage the sensor devices and to collect the patient's data (e.g., robustness against user's misbehaviour or unexpected commands, automatic restart of the application in case of unexpected crashes, and robustness against lacking data connection); cognitive support and feedback messages provided by the application to the user, during the execution of different tasks; user's satisfaction, given by the rate of successful execution of the desired task. The rating of these criteria is not as straightforward as the previous ones, so it is assumed to provide a score that may vary from a minimum value of 1 (the criterion is completely not satisfied) to a maximum value of 10 (the criterion is completely satisfied). The assessment of a specific system from the patient's perspective may be performed through the submission of a questionnaire to the user, asking to rate each single issue.