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Fields Changed

Registration

Field Before After
Trial Status in_development completed
Last Published September 30, 2019 05:28 PM December 08, 2025 08:18 AM
Intervention (Public) We randomly draw general practitioners (GPs) from the universe of all primary care providers active in the outpatient sector in Switzerland to receive peer comparison letters containing information on either their health care expenditures and/or practice style behavior (vaccination or generic drug rates) in comparison to GPs with a comparable risk pool of patients. Primary care providers in the control group receive no social comparison letter. The letter will be sent out once at the beginning of the intervention period and the short-term reaction is tracked after half a year. To capture the long-term response, information on the main outcomes will be gathered again after one year. We randomly assigned general practitioners (GPs) from the universe of all primary care providers active in the outpatient sector in Switzerland to receive peer comparison letters containing information on low-value care (i.e., vitamin D testing and generic substitution) or medical spending in comparison to GPs with a comparable risk pool of patients. Primary care providers in the control group receive no social comparison letter. The letter will be sent out once at the beginning of the intervention period and the short-term reaction is tracked after half a year. To capture the long-term response, information on the main outcomes will be gathered again after one year.
Primary Outcomes (End Points) Primary outcomes of the field experiment are the health care costs (plus cost subcategories) and practice style indicators including the influenza vaccination rate and generic drug rate of GPs active in the Swiss outpatient sector. Primary outcomes of the field experiment are the health care costs (plus cost subcategories) and low-value care services including vitamin D tests and the share of generics prescribed to patients of GPs active in the Swiss outpatient sector.
Planned Number of Clusters 6300 primary care providers 3064 primary care providers (n = 766 per arm)
Planned Number of Observations 6300 primary care providers 3064 primary care providers (n = 766 per arm)
Sample size (or number of clusters) by treatment arms 1600 GPs in the control group (no letter); 1600 GPs in the generic drug rate intervention group; 1500 GPs in the influenza vaccination intervention group; 1600 in the health care cost intervention group 766 GPs in the control group (no letter); 766 GPs in the generic substitution arm; 766 GPs in the vitmamin D testing arm and 766 in the health spending intervention group
Keyword(s) Health Health
Public analysis plan No Yes
Building on Existing Work No
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Analysis Plans

Field Before After
Document
Title Study Protocol & Statistical Analysis Plan
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