Table 1. Definitions for specific recommendations⁵.

Efficacy conclusions	Definition	Required evidence
Efficacious	Evidence shows that intervention has a positive effect on studied outcomes	Supported by data from at least 1 high-quality (score ≥ 75%) RCT without conflicting level-I data
Likely efficacious	Evidence suggests, but is not sufficient to show, that the intervention has a positive effect on studied outcomes	Supported by data from any Level-I trial without conflicting level-I data
Unlikely efficacious	Evidence suggests that the intervention does not have a positive effect on studied outcomes	Supported by data from any Level-I trial without conflicting level-I data
Non-efficacious	Evidence shows that the intervention does not have a positive side effect on studied outcomes	Supported by data from at least 1 high-quality (score ≥ 75%) RCT without conflicting level-I data.
Insufficient evidence	There is not enough evidence either for or against efficacy of the intervention in treatment of Parkinson's disease	All the circumstances not covered by the previous statements
Safety
Acceptable risk without specialized monitoring
Acceptable risk with specialized monitoring
Unacceptable risk
Insufficient evidence to make conclusions on the safety of the intervention
Implications for clinical practice
Clinically useful	For a given situation, evidence available is sufficient to conclude that the intervention provides clinical benefit
Possibly useful	For a given situation, evidence available suggests, but insufficient to conclude that the intervention provides clinical benefit
Investigational	Available evidence is insufficient to support the use of the intervention in clinical practice, further study is warranted
Not useful	For a given situation, available evidence is sufficient to say that the intervention provides no clinical benefit
Unlikely useful	Evidence suggests that the intervention does not have a positive effect on studied outcomes

RCT, randomized controlled trial.