Table 1.
List of features and their descriptions in the initial dataset (the dataset is also available at the website of Data Mining and Biomedical Informatics Lab at VCU (http://www.cioslab.vcu.edu/)).
| Feature name | Type | Description and values | % missing |
|---|---|---|---|
| Encounter ID | Numeric | Unique identifier of an encounter | 0% |
| Patient number | Numeric | Unique identifier of a patient | 0% |
| Race | Nominal | Values: Caucasian, Asian, African American, Hispanic, and other | 2% |
| Gender | Nominal | Values: male, female, and unknown/invalid | 0% |
| Age | Nominal | Grouped in 10-year intervals: [0, 10), [10, 20),…, [90, 100) | 0% |
| Weight | Numeric | Weight in pounds. | 97% |
| Admission type | Nominal | Integer identifier corresponding to 9 distinct values, for example, emergency, urgent, elective, newborn, and not available | 0% |
| Discharge disposition | Nominal | Integer identifier corresponding to 29 distinct values, for example, discharged to home, expired, and not available | 0% |
| Admission source | Nominal | Integer identifier corresponding to 21 distinct values, for example, physician referral, emergency room, and transfer from a hospital | 0% |
| Time in hospital | Numeric | Integer number of days between admission and discharge | 0% |
| Payer code | Nominal | Integer identifier corresponding to 23 distinct values, for example, Blue Cross/Blue Shield, Medicare, and self-pay | 52% |
| Medical specialty | Nominal | Integer identifier of a specialty of the admitting physician, corresponding to 84 distinct values, for example, cardiology, internal medicine, family/general practice, and surgeon | 53% |
| Number of lab procedures | Numeric | Number of lab tests performed during the encounter | 0% |
| Number of procedures | Numeric | Number of procedures (other than lab tests) performed during the encounter | 0% |
| Number of medications | Numeric | Number of distinct generic names administered during the encounter | 0% |
| Number of outpatient visits | Numeric | Number of outpatient visits of the patient in the year preceding the encounter | 0% |
| Number of emergency visits | Numeric | Number of emergency visits of the patient in the year preceding the encounter | 0% |
| Number of inpatient visits | Numeric | Number of inpatient visits of the patient in the year preceding the encounter | 0% |
| Diagnosis 1 | Nominal | The primary diagnosis (coded as first three digits of ICD9); 848 distinct values | 0% |
| Diagnosis 2 | Nominal | Secondary diagnosis (coded as first three digits of ICD9); 923 distinct values | 0% |
| Diagnosis 3 | Nominal | Additional secondary diagnosis (coded as first three digits of ICD9); 954 distinct values | 1% |
| Number of diagnoses | Numeric | Number of diagnoses entered to the system | 0% |
| Glucose serum test result | Nominal | Indicates the range of the result or if the test was not taken. Values: “>200,” “>300,” “normal,” and “none” if not measured | 0% |
| A1c test result | Nominal | Indicates the range of the result or if the test was not taken. Values: “>8” if the result was greater than 8%, “>7” if the result was greater than 7% but less than 8%, “normal” if the result was less than 7%, and “none” if not measured. | 0% |
| Change of medications | Nominal | Indicates if there was a change in diabetic medications (either dosage or generic name). Values: “change” and “no change” | 0% |
| Diabetes medications | Nominal | Indicates if there was any diabetic medication prescribed. Values: “yes” and “no” | 0% |
| 24 features for medications | Nominal | For the generic names: metformin, repaglinide, nateglinide, chlorpropamide, glimepiride, acetohexamide, glipizide, glyburide, tolbutamide, pioglitazone, rosiglitazone, acarbose, miglitol, troglitazone, tolazamide, examide, sitagliptin, insulin, glyburide-metformin, glipizide-metformin, glimepiride-pioglitazone, metformin-rosiglitazone, and metformin-pioglitazone, the feature indicates whether the drug was prescribed or there was a change in the dosage. Values: “up” if the dosage was increased during the encounter, “down” if the dosage was decreased, “steady” if the dosage did not change, and “no” if the drug was not prescribed | 0% |
| Readmitted | Nominal | Days to inpatient readmission. Values: “<30” if the patient was readmitted in less than 30 days, “>30” if the patient was readmitted in more than 30 days, and “No” for no record of readmission. | 0% |