Optimum management of spinal conditions is predicated upon accurate assessment. A variety of spinal assessment measures have been developed, including physical performance and patient self-report measures.¹ Performance-based spinal assessments, used to assess the need for spinal rehab and its effectiveness, provide information about distinct domains of interest that are not detected by physical examination or self-report measures.^1-7 Without an accurate performance measure, you cannot know whether spinal rehab is needed, whether a recommended intervention is effective, or when to stop, and data from inaccurate measures can lead to poor clinical decisions.⁸ Therefore, the first step for practitioners is to select the best performance-based spinal assessment measures.

Qualities of a Good Physical Performance Measure
A good physical performance measure will demonstrate reliability, validity and clinical utility, and it will provide normative data.

Reliability in screening/diagnostic testing is how closely repeated measures on the same subject agree when made by different observers or the same observer at different times.^9,10 If a test is unreliable, test results will change without the patient’s condition really changing. A reliable test is worthless if it is not concurrently valid.

Validity is the degree to which a measurement truly measures what it purports to measure.^11,12 There are two primary methods of testing the validity of physical performance measures: discriminate validity and predictive validity. Ideally, a physical performance measure would demonstrate good validity for both testing models. However, it is acceptable for the measure to demonstrate good validity for just one of the testing models if the other testing model is absent, but has not failed. Moreover, a valid test is able to detect a true-positive and discriminate/predict positive from negative. That is to say, it finds almost all patients who have the condition and hardly any patients who do not have the condition.

Clinical utility is just as important as reliability and validity.¹³ Crucial components of clinical utility for a physical performance test include: 1) simple to administer and interpret, 2) requires a minimum amount of equipment, 3) requires a minimum amount of time to administer, 4) requires a minimum amount of space to administer, and 5) requires a minimum amount of cost to administer.

Normative data is important, because it provides a target of how things should be. It supplies a benchmark that allows for comparisons and monitoring progress. The minimum requirements for normative data for a physical performance measure are that the sample frame be from healthy controls and that the research team provide gender specifics (Assuming the data is from a quality study.).

The Search for Good Physical Performance Measures
The following electronic databases were used to search the literature for relevant studies: MEDLINE, EMBASE, and CINAHL. "Related articles" in relevant MEDLINE (PubMed) papers were accessed, and articles cited in the bibliographies of relevant papers were retrieved. Several popular spinal rehabilitation texts were reviewed (e.g., McGill, Liebenson).

Table 1* provides the assessment of 36 physical performance measures that failed to meet the quality standards set forth herein. Among the measures that failed were the popular cervical and lumbar muscle strength tests.

Table 2* provides the psychometric qualities of 5 test that met the standards of a test that provides good clinical guidance to the doctor and patient. These tests have sound psychometric qualities: they are reliable, valid (discriminate and/or predictive validity), provide clinical utility (inexpensive, quick and easy to perform) and have normative data from healthy controls with gender subgrouping.

* Tables 1 & 2 are available to clients of RJF Consulting.

References
1. Thomas E, Silman AJ, Croft PR, Papageorgiou AC, Jayson MI, Macfarlane GJ. Predicting who develops chronic low back pain in primary care: a prospective study. BMJ 1999;318:1662-7.
2. Simmonds MJ, Olson S, Novy D, Jones S, Hussein T, Lee CE, et al. Physical performance tests: are they psyehometrically sound and clinically useful for patients with low back pain? Spine 1998;22:2412–21.
3. Wittink H, Rogers W, Sukiennik A, Carr DB. Physical functioning: self-report and performance measures are related but distinct. Spine 2003;28:2407-13.
4. Peolsson A, Almkvist C, Dahlberg C, Lindqvist S, Pettersson S. Age- and sex-specific reference values of a test of neck muscle endurance. J Manipulative Physiol Ther 2007;30:171-77.
5. Falla D, Rainoldi A, Merletti R, Jull G. Myoelectric manifestations of sternocleidomastoid and anterior scalene muscle fatigue in chronic neck pain patients. Clin Neurophysiol 2003;114:488-95.
6. Randlbv A, astergaard M, Manniche C, Kryger P, Jordan A, Heegard S, et al. Intensive dynamic training for females with chronic neck/shoulder pain. A randomized controlled trial. Clin Rehabil 1998;12:200-10.
7. Lee H, Nicholson LL, Adams RD. Cervical range of associations with subclinical neck pain. Spine 2003;29:33-40.
8. Finley GA, McGrath PJ. Measurement of pain in infants and children, progress in pain research and management, Introduction: the roles of measurement in pain management and research, Volume 10 edited by Finley GA, McGrath PJ. IASP Press, Seattle, 1998.
9. Norman GR, Streiner DL. Biostatistics: The Bare Essentials. Toronto: Mosby, 1994.
10. Stratford PW, Binkley JM. A comparison study of the back pain functional scale and Roland Morris Questionnaire. North American Orthopaedic Rehabilitation Research Network. J Rheumatol 2000;27:1928-36.
11. Turner JA, Fulton-Kehoe D, Franklin G, Wickizer TM, Wu R. Comparison of the roland-morris disability questionnaire and generic health status measures: a population-based study of workers' compensation back injury claimants. Spine 2003;28:1061-7.
12. Deyo RA, Centor RM. Assessing the responsiveness of functional scales to clinical change and analogy to diagnostic test performance. J Chron Dis 1986a;39:897–906.
13.Simmonds, M. Physical function and physical performance in patients with pain: what are the measures and what do they mean? In: Devor, M, chairman. Pain 1999-an updated review: refresher course syllabus. Seattle: IASP Press.