To conduct a retrospective multicenter cohort study to define benchmark values for best achievable outcomes following transsphenoidal resection of pituitary adenomas.

Surgeons strive for the best possible outcome of their surgeries with the greatest possible chance for recovery of the patients. Therefore, monitoring and quality improvement is increasingly important in surgery. For this purpose, different concepts were developed with the aim to assess best achievable results for several surgical procedures and reduce unwarranted variation between different centers. The concept of a benchmark establishes reference values which represents the best possible outcome of high-volume centers and can be used for comparison and improvement. In the past years, the concept of benchmarking attaches greater importance in the field of healthcare, especially in surgery. Benchmark values are established within a patients' cohort for which the best possible outcome can be expected. To date, no valid concept exists to describe the outcome of patients after transsphenoidal resection of pituitary adenomas. The aim of our study is the establishment of robust and standardized outcome references after transsphenoidal surgery. After successful implantation of benchmarks from an international cohort of renowned centers, these data serve as reference values for the evaluation of novel surgical techniques and comparisons among centers or future clinical trials.

Inclusion Criteria:

• Patients who went through transsphenoidal resection of pituitary adenoma
• Including high-volume centres with ≥50 cases per year

Exclusion Criteria:

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Patients who went through transsphenoidal resection of pituitary adenoma at high-volume centres