Because these are relatively new medicines, their long-term effectiveness has not been studied.

We need to know more about the long-term effectiveness and adverse effects.

The long-term effectiveness of this procedure is not yet known.

But no one has yet completed a study of either regimen to test its long-term effectiveness and safety.

And he said there were not sufficient data on the long-term effectiveness of the treatment.

Still, the long-term effectiveness of the approach remains to be seen.

But no one had ever done a large study on the long-term effectiveness.

In most cases, these treatments have been studied for only a few years, so their long-term effectiveness is not yet known.

Little is known about the long-term effectiveness of either procedure.

But the long-term effectiveness of these changes is unclear.