The abbreviation MSFC stands for the so-called Multiple Sclerosis Functional Composite Index. This is a quantitative examination, in which the 7.6m walking distance, the so-called 9-hole pegboard test and the PASAT3 test, a neurocognitive test, are used to evaluate the functionality of an MS patient.
The MSFC was developed in the USA, the original length of the walking distance was 25 feet, which corresponds to about 7.6 m – hence the “odd” distance for the walking distance. For the test, the time it takes for an MS patient to cover this distance as quickly as possible is determined – walking aids, such as a walking stick or a walker, may be used. The walking distance is thus a test for the function of the lower extremity.
In the 9-hole pegboard test, 9 plastic rods must be taken from their holder (hole) with the hand, placed in a bowl, and then taken out of the bowl again and put back into the holder. Each hand is tested individually, the test is carried out twice, the action should be performed as quickly as possible, the fastest attempt of each hand is evaluated. The 9-hole pegboard test is thus a functional text of the upper extremity.
The PASAT3 test is a neurocognitive test in which the test person hears numbers from a sound carrier at intervals of 3 seconds (hence PASAT3). The test person must always add the last heard number to the latest number. Example: The number 2 comes from the sound carrier, after another 3 seconds the number 5 sounds, the test person must write down 7, after another 3 seconds the number 4 comes from the sound carrier, the test person must now write down 9 etc.
The PASAT3 is anything but easy for healthy normal people. It tests less the ability to calculate than the concentration and the speed of information processing, two abilities that can be affected in MS patients.
The PASAT is anything but popular among many MS patients – tears often flow. For this reason, many practices and clinics have started to replace the PASAT with the SDMT (Symbol Digit Modality Test). This is much more pleasant for the patients to perform. In addition, it is considered the better test for the examination of working memory and speed of information processing. The SDMT presents the numbers 1 to 9, which are assigned to nine symbols. The test person should memorize this assignment briefly. In a row of randomly consecutive symbols, the test person should now assign as many numbers as possible to the corresponding symbols. They have 90 seconds to do this; the test person can look at the given assignment at any time. The number of correctly assigned numbers gives the test result.
The MSFC value – i.e. the summary of the individual test procedures – is obtained by a so-called z-transformation, a standardization procedure necessary to compare differently distributed random variables. Unfortunately, such a z-value is relatively abstract and difficult to interpret. Therefore, in practice, the comparison of the raw data of the individual function tests over time has prevailed. An acceptable value for an improvement or deterioration is considered to be a change in the initial value of about 20%.
The performance in the MSFC correlates quite well with the EDSS value. Unlike the EDSS, however, the MSFC is much quicker and easier to collect and is therefore also suitable for standardized follow-up control. Nevertheless, many medical colleagues have a mixed relationship with the MSFC – they find it absurd that such “simple” tests should succeed in monitoring the course of MS patients. In addition, there is also the justified criticism that the MSFC does not cover all dimensions – such as the visual system – and that a learning effect can be observed with frequent use. As far as covering further dimensions is concerned, work is currently being done to expand the MSFC with tests for the visual system (e.g. boards to determine contrast perception).
Despite this criticism, in my view, the MSFC is a useful tool that allows reliable and standardized follow-up control of MS patients with simple means and thus also plays an important role in the monitoring of MS therapies. Therefore, any future improvement of this system is very welcome.
