Many outcomes "instruments" or questionnaires have been developed and utilized over the last 30 years. One of the first outcomes measures, which had widespread use as a general health measure to date is the SF36 created by the Rand Corporation many years ago in order to follow the general health status of populations. It is not highly specific nor highly selective in demonstrating particular disease conditions, because it was developed to evaluate general health status. It has, however, been widely utilized because of its reproducibility and statistically scrutinized method of development.
Many specific tools have been developed since then in an effort to demonstrate the effectiveness of interventions for more specific disease conditions. In orthopaedics, these include the IKDC, the Tegner, and the Lysholm knee scales as examples. Some of these have been found to be very helpful in measuring specific, functional improvements. This is important in determining the effect of disease specific treatment. Unfortunately, several measures have also been used extensively over the years, which do not show many functional improvements. These measures were often developed more by intuition than by valid statistical means, but have been incorporated in the body of medical literature through use.
The collection of validated outcomes measures is important to improve medical care. These measures along with patient demographics and physician treatment data create a complete outcomes database. However, it should be stressed that because of the many "instruments" available, it is common for physicians to connect several into one and combine similar questionnaires and multiple outcomes. Unfortunately, this is often not an effective means to collect data because each questionnaire is distinct and must be completed individually from start to finish. Combined questionnaires could be proven valid if performed on a large test population. But individual questionnaires, for the most part, have to be analyzed and treated as distinct. Hopefully, with improved data collection efforts, the specificity and sensitivity of the instruments themselves will be improved. In addition, by analyzing separate criteria-based questionnaires, the same or more information can be garnered utilizing fewer questions.