I was reading about Pohazaev type obstructions: precisely, I mean the following kind of results. Let $h\in C^1(\mathbb{R}^n)$ and consider the following Dirichlet problem $$ \begin{cases} \Delta u + hu = |u|^{\frac{4}{n-2}}u &\text{ in }\Omega,\\ u = 0 &\text{ on }\partial\Omega. \end{cases} $$ where $\Omega$ is star-shaped (with respect to the origin) smoothy-bounded domain in $\mathbb{R}^n$ with $n\geq 3$. Then, if $h$ satisfies the inequality $$ h(x) + \frac{1}{2}\langle x,\nabla h(x)\rangle \geq 0, $$ Pohozaev says that there are no non-trivial solutions for the above boundary value problem.
Question. Is there any similar kind of obstruction for higher order elliptic operators?
Final note. In the case of higher order operators, we obviously need a better regularity for $h$ but I am just curious to know if there is there some analogous result for higher order, conformally invariant operators.