"difficult conclusion" is a grammatically correct and usable phrase in written English.
It can be used to describe a conclusion that is challenging, complex, or hard to reach. Here is an example: "After months of research and deliberation, the scientists finally arrived at a difficult conclusion: the cure for the disease was still years away."
This is, of course, a difficult conclusion for us to accept.
As the book approaches its difficult conclusion, the possibility of healing, of atonement, is at least suggested by the narrator's last, extraordinary gesture.
"I am afraid that all of these matters lead me to an unavoidable and difficult conclusion that the risks to [the boy] in being placed with his parents are far too high," said the judge.
He called a meeting of doctors and administrators, and they came to a difficult conclusion: They would need to postpone the seven open-heart operations that were scheduled for the next week.
"Although RSR has been a leading distributor of Smith & Wesson products for more than 20 years we have come to the difficult conclusion that we cannot continue to do business with Smith & Wesson under the problematic terms of the current agreement," the company said.
That wasn't a difficult conclusion to reach, and it didn't need to take seven years; all they had to do was look at their damn signage – all those placards of Obama as "Curious George" the monkey and signs like "OBAMA'S PLAN = WHITE SLAVERY" were kind of unambiguous.
Clearly there are lines of argument with that that could lead to some very difficult conclusions, so it's about balance and moderation.
Albeit differences in local recovery regimens and healthcare systems make comparison between studies difficult, this conclusion can be regarded valid.
First, the small case number and the retrospective study design make drawing statistical conclusions difficult, and no conclusions about recurrence in comparison with other modalities can be made.
In such cases comparison becomes not only difficult but conclusions are drawn which may not apply to similar agro-ecological conditions and soils.
The small sample size of the studies and the observed heterogeneity make generalisable conclusion difficult.
