We will perform a two-step matching process. In the first step, for all patients who received AGR in a determined billing period, we plan to match controls with similar morbidity and cost characteristics during a.) the four billing periods prior to the index period in which the intervention took place, and b.) by additionally including the index period in the matching. This first step allows for the definition of an index period in controls. Using variables during the index billing period is complicated by the fact that no information on the temporal sequence of events within a billing period is available due to legally obliged data protection agreements. However, ignoring the index period may lead to a systematic ignorance of events leading to AGR which might have taken place in the index period. Therefore results from both analysis scenarios (a., b.) will be systematically compared. The first-step will be conducted as an exact match (pre matching) on selected variables listed in Table 6. These variables were selected due to their high expected conceptual importance for the estimation of treatment effects. Should no adequate numbers of controls be found, a more lenient matching may be employed. Controls will be drawn with repetition across billing periods. We plan to match up to 100 controls per case at this stage.Table 6Matching criteriaMatching CriterionPre MatchingPropensity ScoreAgex ± 2 yearsxSexxxArea of residencexDays being insuredxLevel of nursing carexxHospital admission yes/noxxCharlson Comorbidity index (CCI)xDays spent in the hospitalxHospital costs without out-of-pocket spendingxxAmbulatory costsxCosts of remedyxCosts of medical aidxDrug costs without out-of-pocket spendingxxTotal costs with out-of-pocket spendingxMain diagnoses before AGR Musculo-skeletal x a Status post fracture or joint replacement Cox- or gonarthrosis with endoprothesisx Other fractures and injuriesx Other arthropatiesx Osteoporosisx Spondylopathies and Discopathies, possibly with laminectomyx Infection Pneumonia and other lung inflammationsx a x Cardio-vascular system Heart failure Chronic obstructive pulmonary disease (COPD)x Arterial obstructive disease with amputation or other surgeryx a x Coronary heart diseases with surgeryx Stroke and other cerebrovascular diseasesx Neuro-psychiatric Delirium and other organic brain psychosisx Secondary Parkinsonsyndromx a x Symptoms, effecting the nervous system and musculoskeletal systemxCharlson Comorbidity Index Any Malignancyxx Cerebrovascular diseasex Chronic pulmonary diseasex Congestive heart failurex Metastatic solid tumorx Dementiaxx Hemiplegia or paraplegiax Mild liver diseasex Myocardial infarctionx Renal diseasex Peripheral vascular diseasexGeriatric Multimorbidity Cognitive deficitx Chronic painx Depression, Anxietyx Incontinencex Severe visual/hearing impairmentx Paraesthesiax Immobilityxx Chemotherapyxx aAt least one diagnosis from each main diagnosis group will be used to match controls. Diagnoses are allowed to differ between cases and controls within the main diagnoses group