Complications are conditions that arise in a patient's care in the hospital, many of which are believed to be broadly preventable. The complication ratio compares the rate of patient complications in the hospital to the expected rate of complications based on national averages. A ratio of 1.0 is what would be expected based on certain medical problems and illnesses. A ratio less than 1 is lower than expected, while a ratio greater than 1 is higher than expected.