Convergent validity of clinical tests which are hypothesized to be associated with physical functioning in patients...

Up until now, assessment of physical functioning in patients with low back pain is mostly completed with the use of patient reported outcome measurements (PROMs). There are however limitations to the use of these measurements such as inaccuracies due to recall bias, social desirability bias and errors in self-observation. A recent review indicated seven clinical tests as having good test retest reliability. These tests can now be further investigated for their validity.

To investigate the convergent validity of seven clinical tests (extensor endurance, flexor endurance, 5 minute walking, 50 foot walking, shuttle walk, sit to stand and the loaded forward reach test) in patients with nonspecific chronic low back pain (CLBP).

Patients filled in a series of PROMs and performed all included clinical tests during a specific test moment. Convergent validity was firstly investigated by assessing Pearson correlations between the seven included clinical tests and secondly by assessing the correlations between the predefined PROMs and the clinical tests.

Twenty-five patients were included in this study representing a power of 84%. The best overall evidence for convergent validity could be identified for the extensor endurance, sit to stand and the loaded forward reach test. However, when all study results were combined, evidence for convergent validity was found for all included clinical tests except for the shuttle walk test.

The current study was able to provide evidence that multimethod and multidimensional approaches should be used as a more comprehensive assessment of physical function in patients with nonspecific CLBP.