If these are missing, be careful. It is beyond the scope of this book to go into the details of how reports on clinical trials should be assessed, but a few general principles are given here. Generally, only randomized, double-blind clinical trials give valid information about the effectiveness of a treatment. Conclusions drawn from studies of other design may be biased. Finally you should look at the clinical relevance of the conclusion, not only its statistical significance.
Many statistical differences are too small to be clinically relevant.
Sometimes conflicting evidence is presented by different sources. If in doubt, first check on the methodology, because different methods may give different results. Then look at the population studied to see which one is more relevant to your situation. If doubts remain, it is better to wait and to postpone a decision on your P-drug choice until more evidence has emerged.