[Does the lack of evidence of effectiveness among international studies on interventions in prevention and health promotion have an impact on a German Act of Prevention?].

BACKGROUND AND
PURPOSE: Efforts have been undertaken to devise and pass an Act of Prevention in Germany. To date, no consensus could be reached with changing political majorities in parliament. Hence, the authors ask the question whether the lack of evidence in prevention and health promotion could also be contributing to this delay.
METHODS: After a systematic search of the literature on prevention and health promotion in nutrition, exercise, depression, and smoking, all retrieved studies were evaluated in terms of their effect as well as the quality of study design like prior power calculation and intervention like documentation of process or participation of intended group. For inclusion, studies had to be undertaken in one of 13 countries that have a socioeconomic standard of living comparable to Germany. The authors of this article exemplarily included studies from the following focus areas into the systematic review: prevention of depression among children and adolescents, exercise in the work environment, nutrition for children and adolescents, and smoking cessation programs among pregnant women, all from 1990 to 2006.
RESULTS: The authors retrieved 18 studies on prevention of depression among children and adolescents, 26 on exercise in the work environment, 23 on nutrition for children and adolescents, and 34 on smoking cessation programs among pregnant women. Six out of 26 on exercise had a positive effect (23.1%), one out of 18 on depression (5.6%), seven out of 23 in the field of nutrition (30.4%), and nine out of 34 smoking cessation programs (26.5%). If one takes into account the quality of study design and intervention as a marker for the reliability and validity of results, one intervention on exercise, two on nutrition, three on smoking and none on depression would remain with a positive effect.
CONCLUSION: In four exemplarily selected fields only six out of a total of 101 international studies (5.9%) had an effect, if one also ties in quality of study design and intervention. With regard to this result, allocation of resources for prevention and health promotion would be highly ambiguous without sufficient evidence. This condition might contribute to the deferment of an Act of Prevention in the German legislation. For the future, the authors strongly urge that the Act of Prevention takes into account the evaluation both of effects and quality of any intervention in order to prevent false allocation of resources.