Independent Variables and Covariates
hemiplegia, comorbidity, rheumatologic disease, chronic pulmonary disease, cancer, dementia, liver disease, paraplegia, Comorbidity, comorbid diseases, peripheral vascular disease, cerebrovascular disease, diabetes
MYOCARDIAL INFARCTION, CANCER, RECRUITMENT, LIVER DISEASE, RENAL DISEASE, CHRONIC PULMONARY DISEASE, CONGESTIVE HEART FAILURE, PARAPLEGIA, PEPTIC ULCER DISEASE, DIABETES
Patient-level sociodemographic variables from the EHR include (1) age (<30, 30-39, 40-49, 50-59, 60-69, 70-79, ≥80 years); (2) sex (male and female); (3) race or ethnicity (non-Hispanic White, non-Hispanic Black, non-Hispanic Asian or Asian and Pacific Islander [API], Hispanic or Latino, other, multiracial, and unknown or declined to state); (4) insurance (commercial, Medicaid, Medicare, other, and unknown or declined to state); and (5) marital status (married or partnered, not married or partnered, and unknown or declined to state). Insurance status serves as a proxy for individual socioeconomic status (SES) since income levels cannot be ascertained from the EHR. Insurance statuses of Medicaid or unknown or declined to state were used as indicators of lower SES.We derived the following patient-level clinical variables using EHR data extracted from UCSF’s clinical data warehouse: (1) Charlson Comorbidity Index (CCI) score (0, 1, 2, and 3+); (2) diagnosis of medical condition (myocardial infarction, congestive heart failure, peripheral vascular disease, cerebrovascular disease, dementia, chronic pulmonary disease, rheumatologic disease, peptic ulcer disease, diabetes, liver disease (mild, moderate, or severe), paraplegia or hemiplegia, cancer (any type or metastatic solid tumor), renal disease, HIV/AIDS); and (3) UCSF recent patient status (inactive and active). Patients are defined as “active” if they had 1 or more health care encounters at UCSF 6 months prior to the initial email invitation. The CCI score is a validated standardized measure of overall comorbidity burden and generates a weighted index based on the relative risks of 1-year mortality or “the number and seriousness” of 17 comorbid diseases [For recruitment-related variables, we also adjusted for the number of recruitment emails received (1 vs 2). Patients in wave 15 were only delivered 1 (initial) email, while those in waves 1 to 14 had the potential to be delivered up to 2 (initial and follow-up) email invitations.