[Predictors of treatment success after microsurgical operation of lumbar intervertebral disk displacement].

As far as medical decision making is based on weighing up individual risks and chances of a certain patient receiving a certain treatment, some knowledge is required about signs and symptoms which are associated with a certain outcome: they are called risk factors, or predictive factors. In lumbar intervertebral disc surgery, the most frequent undesired effect of the treatment is unsuccessfulness. Reviewing the literature about risk factors for unsuccessfulness, one recognizes a lot of unconfirmed or even contradictory findings. This inconsistency can possibly be attributed to the common use of a very simplified, unidimensional definition of the target variable "success of treatment". That is why we performed a prospective observational trial on 109 patients in whom the success of lumbar intervertebral disc microsurgery was assessed after half a year using six different target variables. The rate of treatment success varied considerably, from 44% (when "return to previous occupation" served as the target variable) to 91% (with regard to "subjective contentedness"). Further target variables were intensity of sciatica, intensity of low back pain, activities of daily living, and postoperative paresis, giving intermediate success rates. We were able to identify some risk factors (for instance, duration of sick leave and of the recent pain episode, preoperative paresis, intensity of psychosomatic complaints), each of them being relevant to some of the target variables, but none of them associated with all of the target variables. We conclude that the multidimensional rating of treatment successes seems to promote risk research in multidimensional diseases.