Functional capacity evaluations – my take on them!
Functional capacity evaluations
There are many forms of functional assessment available. These range from a series of structured activities carried out in the home or work environment over a period of days or weeks to those that are carried out in a very precise manner in a clinic and often under the supervision of an occupational therapist or physiotherapist. Both commercial (ie standardised and franchised) ‘Functional capacity evaluations’ (FCE) are available, as well as semi-structured or individualised assessments.
The term functional capacity evaluation has been criticised, because it can suggest that it is able to assess ‘capacity’ or ‘can do’, while most commentators believe that functional assessments can only assess what a person ‘will do’ (e.g. Battie & May, 2001).
One of the major criticisms of FCE is that few studies of reliability or validity have been published in peer reviewed journals. This means most FCE have not been subject to the degree of scrutiny that is usually employed when developing assessment tools. The relatively few studies that are available suggest that ‘only limited aspects of FCE reliability have been studied’ (Battie & May, 2001), and predictive validity, or the ability of the FCE to predict whether someone can or will return to work, is not strong (e.g. Gross, Battie & Cassidy, 2004)..
Reliability refers to whether two different people can conduct the FCE and obtain the same results (e.g. inter-rater reliability). Intra- and interrater reliability for most FCE methodologies have not been established. There is some evidence that interrater reliability for establishing between ‘light’ and ‘heavy’ exertion, and whether a lift is performed safely, but mixed findings have been obtained for identifying the level that would ‘constitute safe, maximal lifting’ (Battie & May, 2001). This means that when reviewing the findings of FCE, it is uncertain whether the same results would be achieved a second time, or by a different assessor.
Validity refers to whether an assessment is measuring the dimension it says it is measuring. There are several different types of validity – content validity refers to whether the items used in the assessment ‘look like’ and agree with other ways of measuring a similar area – for example, do the items in the FCE measure the same sort of areas that disability questionnaires measure? If they do, there should be a degree of similarity between the scores on both type of assessment if they’re completed by the same person.
Reneman et al. (2002) found little to moderate correlation between the self-report and performance-based measures, while Gouttebarge et al. (2009) found poor construct validity of lifting tests, discriminative validity was not statistically established, and convergent validity with self-reported pain intensity and disability was poor.
One of the most important aspects of validity is whether the results from an assessment can be used to predict behaviour in the ‘real world’ – this is predictive validity. Gross and Battie (2005), found that FCE did not predict function at 12 months, and stated in a further paper that ‘The validity of Functional Capacity Evaluation’s purported ability to identify claimants who are “safe” to return to work is suspect.’ (Gross, Battie & Cassidy, 2004). A very recent study demonstrated that while FCE was related to return to work the predictive efficiency is poor, with the findings contributing only 5% to the overall model (Striebelt, et al.2009).
Strong and colleagues provide recommendations as to how FCEs should be requested, undertaken, reported and particularly applied to reduce work disability among injured workers and this paper, in part, describes my approach with clients when discussing the relevance and limitations of FCE results (Strong et al. 2004).
FCE can provide some helpful information to both client and health provider when used as a ‘pre and post’ assessment, to monitor functional improvement, and to assist a client to develop an awareness of the areas of functional performance he or she may need to improve on (such as improving grip strength, manual handling technique or cardiovascular fitness). At the same time, FCE is a measure of volitional behaviour at one time in a clinical setting, as opposed to a ‘real world’ setting where consistent performance is necessary. As I have indicated above, the predictive validity of FCE is not strong, and FCE should not be relied upon to determine ability to carry out activities over the course of a day or week.
Gouttebarge, V., Wind, H., Kuijer, P. P., Sluiter, J. K., Frings-Dresen, M. H., Gouttebarge, V., et al. (2009). Construct validity of functional capacity evaluation lifting tests in construction workers on sick leave as a result of musculoskeletal disorders. Archives of Physical Medicine & Rehabilitation, 90(2), 302-308.
Gross, D. P., & Battie, M. C. (2006). Functional Capacity Evaluation Performance Does Not Predict Sustained Return to Work in Claimants With Chronic Back Pain. Journal of Occupational Rehabilitation, 15(3), 285-294.
Gross, D., Battie, M., & Cassidy, J. (2004). The prognostic value of functional capacity evaluation in patients with chronic low back pain: part 1: timely return to work. Spine, 29(8), 914-919.
Gross, D. P., Battie, M. C., Gross, D. P., & Battie, M. C. (2004). The prognostic value of functional capacity evaluation in patients with chronic low back pain: part 2: sustained recovery Spine, 29(8), 920-924.
Reneman, M. F., Jorritsma, W., Schellekens, J. M., & Goeken, L. N. (2002). Concurrent validity of questionnaire and performance-based disability measurements in patients with chronic nonspecific low back pain. Journal of Occupational Rehabilitation Vol 12(3) Sep 2002, 119-129.
Soer, R., Groothoff, J. W., Geertzen, J. H. B., Cp, Reesink, D. D., & Reneman, M. F. (2008). Pain response of healthy workers following a functional capacity evaluation and implications for clinical interpretation. Journal of Occupational Rehabilitation, 18(3), 290-298.
Streibelt, M., Blume, C., Thren, K., Reneman, M. F., & Mueller-Fahrnow, W. (2009). Value of functional capacity evaluation information in a clinical setting for predicting return to work. Archives of Physical Medicine & Rehabilitation, 90(3), 429-434.
Strong, S., Baptiste, S., Clarke, J., Cole, D., & Costa, M. (2004). Use of functional capacity evaluations in workplaces and the compensation system: A report on workers’ and report users’ perceptions. Work, 23(1), 67-77.