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Outcome-measure instruments are used to determine the patient's current functional status, the impact of a condition on the patient's life, and the extent to which an intervention is helping the patient. Initially, outcome measures were primarily employed for research, but their use has expanded so that functional outcome measures and disability questionnaires are completed at regular intervals to document the patient's progress over time. When collectively examined, outcome measures form the basis of data used to determine if an intervention is effective.
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Quantifying the extent of a patient's range of motion (ROM), a clinician-rated outcome measure, may provide valuable data regarding body structure and function, but it tells us little about how the patient is actually functioning in everyday life. Other clinician-rated measures, such as a single-leg hop for distance, assess functional performance to quantify specific functional activities. Both generic and condition-specific patient-rated outcome measures capture the impact of a condition across the disability spectrum.1
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During a clinical examination, we typically question patients about the impact of the condition on their life (e.g., activity limitations). Patient-rated outcome measures provide a standardized, objective means to quantify the patient's impairments and how to best tailor an intervention to a particular patient. For example, the patient who identifies that her knee pain is limiting her ability to run more than 20 miles would likely have a different series of interventions than the patient whose knee pain prevents her from walking more than 100 yards. The integration of patient-based outcome measures into the examination process is critical to patient-centered care.
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Interpreting the results of patient-based outcome measures requires a basic understanding of the instrument, its target population, and what change in the score is meaningful. Many outcome measures have been validated on nonathletic populations and therefore are not adequately responsive to assess change or disability in an athlete. Consider, for example, a basketball player who is fully participating in practice yet still reports lingering effects from an ankle sprain. This person may score the highest possible total on a patient-rated outcome measure yet still may not be at the preinjury performance level. Some outcome measures incorporate a sports subscale to avoid this ceiling effect, the point where the instrument's score is no longer meaningful.
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Using the same outcome measure on the same patient for the same condition provides information regarding the patient's progress. Two values, the minimal detectable change (MDC) and minimally clinically important difference (MCID), are important to interpreting results. The MDC describes the change that exceeds the boundaries of measurement error. For example, if a goniometric measurement has an error of plus or minus 5 degrees, then a daily change of 4 degrees in a patient's ROM does not constitute a detectable change. A detectable change, however, may not be important to the patient. The MCID value represents the smallest amount of change that is perceived as beneficial to ...