The patients included in PRÄP-GO and the corresponding comparison cohorts will be offered to participate in this complementary study in order to be able to carry out a detailed characterization and phenotyping of the frailty complex. Amendment vote of 08/05/2024: Recruitment extension of Non-frail surgical control group (NFC cohort) until August 31, 2025.

As part of the innovation fund project PRÄP-GO (EA1/225/19), a multimodal intervention is being conducted in patients with a frailty syndrome. However, the health care research project is limited to evaluating clinical issues only. In order to be able to research further pathophysiological, clinical, psychosocial and work-organizational connections, different groups of participants will be offered the participation in this scientific support program of PRÄP-GO. The groups of participants in this accompanying program ANA-PRÄP-GO are: * Randomized study patients with a frailty syndrome of the intervention study PRÄP-GO (PG cohort) * Non-frail surgical control group (NFC cohort) * Non-surgical comparison group (NO cohort) * Participants with health professions (GB cohort) Additionally, relatives of the patients can be included. Subprojects are included to reflect research questions of interest in sub groups: * Success of endoprosthetic implants (clinical outcome and gait pattern after total hip arthroplasty and total knee arthroplasty in frail patients) * Functional treatment outcome and health-related quality of life after elective spinal surgery in the PG cohort, in the NFC cohort, and in the NO cohort * Hemodynamic evaluation in patients of the PG and NFC cohort with preoperative abnormal cardiovascular function * Establishment of a German standard database for 14 CANTAB tests by CANTAB Connect technology * Aggregated evaluation of the cognitive data of different surgical cohorts from studies carried out at the department of anesthesiology to describe domain-specific changes in the perioperative course * Perspectives of different health professional groups regarding barriers and facilitators in the implementation of a prehabilitation program and necessary changes in skill, organizational and management, and communication in an interdisciplinary setting * Perspectives of patients and significant others regarding the organizational pathway of the prehabilitation program * Frequency, pathophysiology and trajectory of muscle weakness as well as functional impairments of patients admitted to intensive care units of the PG and NFC cohort and their long-term outcomes. * The gut microbiome as a potential risk factor for perioperative neurocognitive disorders (PNDs) in the elderly * Evaluation of nutrition data in all cohorts (e.g. adherence to mediterranean diet, nutrition habits, nutritional status, dental status etc.)