Table 1.
Variable definition and summary statistics.
| Variable | Mean (SD) | Range | Definition |
| Portal usage | 5.094 (11.369) | 0-476 | The number of patient portal sessions each month |
| Web usage | 3.610 (8.695) | 0-476 | The number of patient portal sessions each month from web (desktop) devices |
| Mobile usage | 1.484 (6.945) | 0-352 | The number of patient portal sessions each month from mobile devices |
| COVID_Period | 0.509 (0.500) | 0-1 | Whether the month is March 2020 to August 2020 |
| Minority | 0.212 (0.409) | 0-1 | Whether the patient is Black or Hispanic |
| Age | 53.028 (16.447) | 15-102 | The age of the patient in 2020 |
| Gender (male=1) | 0.377 (0.485) | 0-1 | The gender of the patient |
| BMI | 30.763 (7.935) | 12.87-71.01 | The most recent BMI of the patient |
| Abnormal BPa | 0.641 (0.480) | 0-1 | Whether the patient’s most recent BP is above 120/80 |
| COVID problem | 0.005 (0.069) | 0-1 | Whether the patient had a COVID-19–related ICD-10b code |
| Office visits | 0.547 (1.034) | 0-25 | The number of office visits made by the patient in the previous month |
| Income (US $1000) | 76.07 (44.282) | 18.635-931.273 | Average adjusted gross income of the patient’s zip code from the IRSc |
| Education attainment | 0.360 (0.161) | 0-0.867 | The percentage of the population (aged ≥25 years) with higher education degrees of the patient’s zip code from the USCBd |
| Medical problems | 14.900 (12.219) | 0-136 | The number of active problems and conditions each month |
aBP: blood pressure.
bICD-10: International Classification of Diseases, 10th Revision.
cIRS: Internal Revenue Service.
dUSCB: US Census Bureau.