|CHAPTER 3: PHYSICAL AND REHABILITATION MEDICINE (PRM) - CLINICAL SCOPE
|Year : 2019 | Volume
| Issue : 2 | Page : 47-54
3.5 Physical and rehabilitation medicine: Clinical Scope – Outcomes of physical and rehabilitation medicine programs
Department of Clinical and Experimental Sciences, University of Brescia, Brescia; IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy
|Date of Web Publication||11-Jun-2019|
Prof. Stefano Negrini
Department of Clinical and Experimental Sciences, University of Brescia, Brescia; IRCCS Fondazione Don Carlo Gnocchi, Milan
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Negrini S. 3.5 Physical and rehabilitation medicine: Clinical Scope – Outcomes of physical and rehabilitation medicine programs. J Int Soc Phys Rehabil Med 2019;2, Suppl S1:47-54
|How to cite this URL:|
Negrini S. 3.5 Physical and rehabilitation medicine: Clinical Scope – Outcomes of physical and rehabilitation medicine programs. J Int Soc Phys Rehabil Med [serial online] 2019 [cited 2019 Aug 20];2, Suppl S1:47-54. Available from: http://www.jisprm.org/text.asp?2019/2/2/47/259339
| Introduction|| |
Outcomes have always been important in medicine because doctors' care about what finally happens to their patients. Outcomes determine the continuation or termination of treatments and this was true also in the ancient, fully experience- and tradition-based medicine. In the actual modern evidence-based medicine outcomes are even more important, since they drive health systems at all levels: micro (patients' direct care), meso (health services), and macro (health policies). The physical and rehabilitation medicine (PRM) specialty is an integral part of this evolution and must be based on well-defined outcomes, on one side to provide good treatments, services, and policies, on the other to be well recognized and identified among the other specialties and by health-care providers and politicians.
Classical outcomes of medicine have been measured in terms of morbidity (the incidence of disease, the rate of illness in a specified population or group) and mortality (the proportion of deaths in the population). We are now entering the new era of another key outcome for medicine, functioning, i.e., all what human bodies do and the actions that people perform. In the International Classification of Functioning, Disability, and Health (ICF), functioning is operationalized in terms of domains, and these are partitioned into the dimensions of body functions and structures, activities and participation. We used to think of this evolution as internal to PRM, but in fact, it relates to all medicine and health systems, as clarified by the World Health Organization: the problems of measuring functioning, that will be discussed here, pertain to all fields of medicine and not only to PRM.
Outcomes need to be measured to be fully understood and well used. PRM is a young specialty, and its core interests go far beyond illness and/or body structures and functions, focusing in general on functioning and specifically on activities, while carefully looking at participation. The difficulty in measuring functioning has been at the base of research difficulties in PRM for decades, since these outcomes could almost not be measured in the last. In the past 20 years, we have seen an enormous growth of measurement tools that allowed the steady growth seen in rehabilitation research:, this evolution is not yet finished, and measurements systems still need to be well-defined and refined. In PRM, there are now many outcome instruments to be used for research purposes, but also in hospitals (micro-level); unfortunately, only a few of these instruments are today recognized at the meso-level (i.e., health services), and almost nothing arrives at the macro-level (policy), where the knowledge about functioning and its importance remains low.
The scarce information about functioning at the political level is greatly linked to the absence of data from outcome instruments that should be properly classified to reach the macro-level. This situation greatly impairs the PRM specialty, but also, in general, the evolution of medicine beyond morbidity and mortality toward functioning. The only real classification system for functioning existing today is ICF, but its success as a general framework does not correspond to a similar achievement as a real classification system in everyday clinical life. Unfortunately, in a PRM perspective, ICF is not yet used to collect all the relevant information we need to inform the political (macro-level) and the local health system management (meso-level).
The evolution of our outcome instruments to make them fully ICF compatible is needed not only to make them more uniform and overall coherent but also to give strength to functioning understanding and ultimately to the PRM specialty. Perhaps in the future, we will have something better than ICF, but now, we must recognize that this is the classification we have, and we must use it for purposes highly relevant to our specialty, that go far beyond the everyday clinics.
| Outcome Instruments in Clinical Practice|| |
In the general progress of PRM from a “compassionate” (rehabilitation is not denied to anybody) to a modern comprehensive model, where rehabilitation should be given to patients able to improve, in a specific period of time of the health condition, with a start and an end of treatment, outcome instruments play a pivotal role. The so-called “rehabilitation cycle” has been described and it has been proposed as an instrument to enable all professionals to coordinate their actions [Figure 1]. The rehabilitation process starts with the medical diagnosis and continues as long as the person needs rehabilitation interventions. The classical Rehab cycle includes four stages: assessment; assignment (goal-setting); intervention; and evaluation. Even if it has been formally described as split from the other three phases, the evaluation phase (considered as the application of the outcome instruments) is cross-sectional to all the other phases: while the assessment must be comprehensive and will serve to set the goals, the outcome instruments must be applied to quantify the baseline situation of the patient and set the expected results according to the goals in the short and long term (assignment); each intervention proposed shall be based on, and continuously monitored through the outcome instruments; the final evaluation phase is the decisional phase in which, according to the outcomes, it will be decided if to reiterate the process or discharge the patient. Accordingly, we propose here a modified Rehab cycle, including an evaluation cycle [Figure 1].
|Figure 1: Modified Rehab-Cycle, including the Evaluation Cycle. The modification underlines the transversal place of Evaluation (application of outcome instruments), which is not one of the four phases of the Rehab Cycle but should be applied throughout all phases. Furthermore, after the new “Outcome” phase, discharge as a possible final result has been added, if reiteration is not considered necessary|
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Outcome instruments are related to the clinical situation considered and the single patient under observation. Outcome instrument results will also serve, when properly collected, to inform the meso- and macro-level, but the first application is totally individualized (micro-level). This makes very high the number of outcome instruments into a single specialty. PRM is the primary medical specialty responsible for the prevention, medical diagnosis, treatment, and rehabilitation management of persons of all ages with disabling health conditions and their comorbidities, specifically addressing their impairments and activity limitations to facilitate their physical and cognitive functioning (including behavior), participation (including quality of life), and modifying personal and environmental factors. For this reason, and because of the multiprofessional teamwork typical of PRM, the number of outcome instruments in our specialty is even higher than in other so-called “organ-based” medical specialties. A classification would be advisable, but it is well known how difficult it is to classify PRM interventions and consequently also outcomes.
Some big categories of outcomes can be recognized. While physicians are mostly concerned with objective external measurement systems, in PRM also subjective measurements are of paramount importance: the first have been defined as performance-based assessments, while the latter are called patient-reported outcomes (PRO). Another important distinction is between generic and disease-specific measurement systems: the first have the advantage that they can be applied in various pathologies and allow comparisons between them, but they usually have less precision than the second in front of a specific group of patients. Finally, there are some generic measures of functioning that allow to compare patients across different structures and levels of care and consequently have become standards in some health systems, such as the Barthel Index and the Functional Independence Measure.
In the actual absence of an agreed classification system for outcome instruments, and due to their high number, it is impossible to discuss all of them. The White Book of PRM in Europe broadly classified the outcomes of PRM interventions and programs as follows: functional, person-centered, cost-effectiveness, and survival outcomes. Another classification has been proposed in a reference paper about patient-based outcome measures by Fitzpatrick et al., including disease-specific, site-specific, dimension-specific, generic, summary items, individualized, and utility instruments. We propose here two different approaches. The first, as shown in [Table 1], is an ICF coherent classification proposed in the PM&R Knowledge Now website of the American Academy of Physical Medicine and Rehabilitation. The second one is reported in [Table 2] and comes from a very useful online database produced by the Shirley Ryan Ability Lab of Chicago, aimed at collecting all rehabilitation measurement instruments, where, they are classified as reported in [Table 2].
|Table 1: A suggested classification of outcome measurements in rehabilitation according to the International Classification of Functioning model|
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|Table 2: Classification of outcome measurements in rehabilitation according to the online rehabilitation measures database|
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The burden of the choice of the correct outcome instruments remains on the shoulder of the individual physician according to his patient's needs. In the next paragraphs of this chapter, we will focus on some basic principles that should be known to choose the correct outcome instrument. The final choice depends on the characteristics of the outcome measurement instruments and how they adapt to the individual clinical and/or research purposes.
| Outcome Instruments Basic Knowledge|| |
Whenever humans measure they are prone to a measurement error, that in statistics is different from a mistake: while the error is recognized, accepted, and measured, the last is not. Mistakes happen in judging the results of measurements when the measurement error and characteristics are not considered. A simple definition of the measurement error is the difference between a measured value of a quantity and its true value. It can be systematic (due to a constant characteristic of the measurement) or random (due to the variability of the measurement system or the object measured). For example, measuring a postural parameter, there could be an error of the operator, of the measuring instrument, but also of the measured object, i.e., little movements of the subject. These random errors are unavoidable, and whenever measuring in clinics or research, these errors must be known and quantified not to make judgment mistakes.
The main criteria to choose outcome measurements are reported below. We mostly used the definitions recently developed by Consensus-based standards for the selection of health measurement instruments (COSMIN) for the health-related PRO (HR-PRO). COSMIN also proposed a comprehensive view of the relation among the different measurement properties of HR-PRO [Figure 2].
|Figure 2: COSMIN taxonomy of relationship of measurement properties. COSMIN: Consensus-based Standards for the selection of health measurement instruments, HR-PRO: Health-Related Patient Reported Outcome|
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- Appropriateness: does the outcome instrument match the specific purposes and questions of the evaluation? This is a key question, but it is ultimately a judgment by the evaluator looking at the contents of the instrument as well as to the factors listed below
- Reliability (extended definition): the degree to which the measurement is free from measurement error. A longer and complete definition of COSMIN is: the extent to which scores for patients who have not changed are the same for repeated measurement under several conditions: for example, using different sets of items from the same HR-PRO (internal consistency), over time (test/retest) by different persons on the same occasion (interrater), or by the same persons (i.e., raters or responders) on different occasions (intra-rater). Reliability is not a fixed property but is in relation to the purpose and setting. It is based on specific evaluations that must be performed before introducing a measurement instrument in clinics: without these evaluations, an instrument must not be adopted because it cannot be considered reliable. Its measurement properties include:
- Reliability: The proportion of the total variance in the measurements which is because of “true” differences among patients
- Internal consistency: the degree of the interrelatedness among the items
- Measurement error: The systematic and random error of a patient's score that is not attributed to true changes in the construct to be measured.
Validity: the degree to which an HR-PRO instrument measures the construct (s) it purports to measure. Its measurement properties include:
- Content validity: The degree to which the content of an HR-PRO instrument is an adequate reflection of the construct to be measured. This is not measurable and is greatly influenced by the involvement of patients (and not only experts) since the early stages of development of the measurement instrument. An aspect of this measurement property is:
- Face validity: The degree to which (the items of) an HR-PRO instrument indeed looks as though they are an adequate reflection of the construct to be measured
Construct validity: The degree to which the scores of an HR-PRO instrument are consistent with hypotheses (for instance with regard to internal relationships, relationships to scores of other instruments, or differences between relevant groups) based on the assumption that the HR-PRO instrument validly measures the construct to be measured. It is checked quantitatively, through a series of studies to correlate with other instruments measuring the same construct. The aspects of this measurement property are:
- Structural validity: The degree to which the scores of an HR-PRO instrument are an adequate reflection of the dimensionality of the construct to be measured
- Cross-cultural validity: The degree to which the performance of the items on a translated or culturally adapted HR-PRO instrument are an adequate reflection of the performance of the items of the original version of the HR-PRO instrument.
Criterion validity: The degree to which the scores of an HR-PRO instrument are an adequate reflection of a “gold standard.”Other aspects of validity not defined by COSMIN since they have not been considered relevant for HR-PRO include:
- Convergent and discriminant validity: the degree to which two measures demonstrate similar (convergent) or different (discriminant) results assessing theoretically similar or different constructs respectively. They are both considered aspects of construct validity
- Concurrent validity: Establishes validity when two measures are taken at relatively the same time, often indicates that the test could be used instead of a gold standard
- Predictive validity: Indicates that the outcomes of an instrument predict a future state or outcome.
Responsiveness: The ability of an HR-PRO instrument to detect change over time in the construct to be measured. This domain includes important characteristics of measuring instruments such as effect size, sensitivity and specificity, receiver-operating characteristics, ceiling, and floor effectsPrecision checks the number and accuracy of distinctions made by an instrument. Factors to be considered here include the categories used, the numerical value connected with ordinal scales, the distribution of items versus the clinical reality to be described, the dimensions included in the scalesInterpretability: The degree to which one can assign qualitative meaning - that is, clinical or commonly understood connotations - to an instrument's quantitative scores or change in scores. Some measures have been established and are really relevant in this domain:
- Minimal detectable change: a statistical estimate of the smallest amount of change that can be detected by a measure that corresponds to a noticeable change
- Minimal clinically important difference: represents the smallest amount of change in an outcome that might be considered important by the patient or clinician
- Standard error of measurement assesses response stability in a set of repeated scores. Clinically, it is the amount of error that you can consider as measurement error
- Cutoff scores: designates a positive or negative test outcome
- Floor/Ceiling effects: they occur when a measure's lowest (floor) or highest (ceiling) score is unable to assess a patient's level of ability. It depends on the range of the scale used versus the object measured. In clinics, a scale could well measure the patient at the start, but not at the end of treatment, due to the intervened changes
- Normative data: provides “normal” values for specific variables within a population.
Acceptability: is the instrument acceptable for respondents (patients)? It includes the evaluation of response rates, reasons for not completion, time to complete but also translation and cultural applicability: the last is mandatory countries/cultural contexts different from those where the instruments were developedFeasibility: Is the effort, burden, and disruption to staff and clinical care from the use of the instrument acceptable?
Even if appropriateness, precision, and interpretability are less discussed than the others, this list of outcome instruments properties can help to choose them on an evidence base according to the individual needs. In fact, outcome instruments will never be universally valid, since the properties are related to the specific use, and this makes their choice complex.
Finally, it is worth mention Rasch analysis, that is an original item response theory analysis based on latent trait modeling. The main idea is that there is a direct relationship between the difficulty of an item in a rating scale and the so-called “latent-trait,” that is what the scale is meant to measure. Starting from this principle, it is possible to develop a ruler to measure both the item difficulty and the subject “latent-trait:” this ruler is linear and quantitative even if the starting scale is ordinal. Rasch analysis checks if the items in a scale fit the model, show redundancy, present local dependence, or show differential item functioning: as a result, usually 10–15 items are finally chosen to evaluate the “latent-trait.” Rasch analysis is a modern and advanced tool to develop and to check the outcome instruments in PRM.
| Conclusion|| |
Outcome instruments are at the base of PRM clinical practice. PRM specialty has specific outcomes according to its scope, and they can be described using the ICF framework. PRM-specific outcome instruments must be used at all levels of care: micro (individual patients), meso (health services), and macro (health policies). PRM research developed in the last decades some good instruments, but we are still in a developing phase, and a sound classification of outcome instruments is lacking. Their choice in clinical practice is related to individual situations and should take well into account the characteristics of the instrument.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]