Clinical Prediction Rules
Original Editor - Alistair James
Clinical prediction rules (CPRs) are mathematical tools that are intended to guide physiotherapists in their everyday clinical decision making. CPRs provide physiotherapists with an evidence-based tool to assist in patient management when determining a particular diagnosis or prognosis, or when predicting a response to a particular intervention. In other words, CPRs are diagnostic, prognostic, or interventional/prescriptive. To date, the large majority of CPRs within the physiotherapy literature are prescriptive in nature.The popularity of CPRs has increased greatly over the past few years.
In many ways much of the art of physiotherapy boils down to playing the percentages and predicting outcomes. For example, when physiotherapists do a subjective assessment with a patient they ask the questions that they think are the most likely to provide them with the information they need to make a diagnosis. They might then order the objective assessment tests that they think are the most likely to support or refute their various differential diagnoses. With each new piece of the puzzle some hypotheses will become more likely and others less likely. At the end of the assessment the physiotherapist will decide which intervention is likely to result in the optimal outcome for the patient, based on the information they have collected.
Given that the above process is the underlying principle of physiotherapy clinical practice, and bearing in mind the ever increasing time constraints imposed on physiotherapists, it is unsurprising that a great deal of work has been done to facilitate physiotherapists and patients to make decisions. This work in referred to by many names: CPRs, prediction rules, probability assessments, prediction models, decision rules, risk scores, etc. All describe the combination of multiple predictors, such as patient characteristics and investigation results, to estimate the probability of certain outcomes or to identify which treatment is most likely to be effective.
Despite the increasing popularity of CPRs, they are not without limitations and should be subjected to the scientific scrutiny of continued methodological sound research. Despite the fact that the majority of CPRs useful to physiotherapists exist in the initial stages of development, in the absence of strong evidence, they are capable of proving useful information to the physiotherapist that may in turn enhance patient outcomes. CPRs should not be constructed as removal of the clinical decision-making process from physiotherapy practice. Instead, they should be used to eliminate some of the uncertainty that occurs with each and every clinical encounter and provide a level of evidence on which physiotherapists can make decisions with adequate confidence. The idea is to stick with the principles of evidence-based practice, and to incorporate the best available evidence (including CPRs) combined with clinical expertise and patient preference to improve the overall quality of care provided to individual patients.
There are 3-step process for developing and testing a CPR prior to widespread implementation of the rule in clinical practice. The purpose of this update is to describe the different steps involved in developing and validating CPRs and illustrate how CPRs can be used to improve decision making in physical therapist practice.
- The First Step: Creating the Clinical Prediction Rule :Researchers and practitioners may initially brainstorm to develop a list of all possible factors that they believe have some predictive value for identifying the condition of interest. Ultimately, a reasonable list of predictors are selected for consideration based on clinical experience and previous research, which demonstrates that the factor or set of factors has some diagnostic or prognostic accuracy.
- The Second Step: Validating the Clinical Prediction Rule :Before a CPR can be recommended for use in clinical practice, it is necessary to validate the CPR in a “test set” or “validation set” to ensure that similar results are replicated in a different population of patients or in a different health care setting.
- The Third Step: Conducting an Impact Analysis:a CPR is useful only to the extent that it can improve clinically relevant outcomes, increase patient satisfaction, and decrease costs once it is implemented into the realities of busy clinical practice. The final step in the development of a CPR, therefore, involves assessing the impact of its implementation on practice patterns, outcomes of care, and costs.
Validity and Applicability
There is much debate with regards to their validity and clinical applicability and taking in to consideration results from contemporary research, we should caution clinicians in using them. The results from the available data do not support the use of clinical prediction rules in the management of non-specific low back pain. The current body of evidence does not enable confident direct clinical application of any of the identified CPRs. There is, at present, little evidence that CPRs can be used to predict effects of treatment for musculoskeletal conditions. The principal problem is that most studies use designs that cannot differentiate between predictors of response to treatment and general predictors of outcome. Currently only 1 CPR, the one classifying patients in a group likely to benefit from spinal manipulation, is at the validation stage of development within an randomised control trial (RCT) designed to predict response to treatment. All other CPRs are still at a derivation level. Validation of these rules is imperative to allow clinical application.
For now, CPRs are in no way able to replace sound clinical reasoning. Assessment of patients should still rely on a continuous process of testing of (multiple) hypotheses through history taking, physical examination using validated clinimetrical instruments and outcome measures incorporated in clinical expertise. The P.I.T. demonstrated in this article is sometimes unjustly used as a specific test to include a potential “instability”; clearly that is not it’s function. It should only be used within the specified CPR.
Last but not least, using CPRs clinician tend to classify patients into just one group, where it is highly unlikely that one would treat patients with low back pain with just one single intervention (manipulation). It is more likely that patients will benefit from multimodal therapy incorporating a combination of interventions. A regime of manual therapy and exercise has been shown to be the more effective treatment in many spinal musculoskeletal problems, such as cervicogenic headache, radiculopathy, hip, ankle and shoulder problems.
So perhaps using a CPR as “hindsight”, to underpin the hypothesis derived after a sound clinical reasoning process, is a better clinical way forward.
- Canadian Cervical Spine Rules
- Carpal Tunnel Syndrome
- Cervical Radiculopathy
- Well's Criteria: CPR for Deep Vein Thrombosis
- Meniscal Pathology
- Ottawa Ankle Rules
- Ottawa Knee Rules
- Pittsburgh Knee Rules
- Pulmonary Embolism
- Rotator Cuff Pathology
- Subacromial Impingement
Prescriptive CPRs are an exponent of the treatment-based system. In this type of diagnostic classification system, a cluster of signs and symptoms from the patient history and physical examination is used to classify patients into subgroups with specific implications for management. As such, it produces homogenous subgroups where all patients within that group are expected to respond favourably to a matched intervention.
- Cervicothoracic Manipulation for Shoulder Pain
- CPR for Lumbar Stabilisation
- Hip Mobilization for Knee Osteoarthritis
- Manipulation for Low Back Pain
- Treatment Based Classification System Approach for Low Back Pain
- Mechanical Traction for Neck Pain
- Manipulation for Patellofemoral Pain Syndrome
- Orthotics for Patellofemoral Pain Syndrome
- Patellar Taping for Patellofemoral Pain Syndrome
- Stabilization for Low Back Pain
- Thoracic Manipulation for Neck Pain
- Cervical Manipulation for Neck Pain
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