Setting
The clinical setting and database were previously described [6]. In brief, the study took place at Children’s Medical Center Dallas, a large urban pediatric teaching hospital licensed for 487 beds, with a 72-bed hospital also owned by Children’s Health System of Texas and staffed by the same endocrinology group located 22 mi (35 km) north. This study was approved by the UT Southwestern Institutional Review Board. Data were obtained using SAP (Walldorf, Germany) analytics to interrogate a Clarity database derived from our institutional Epic (Madison, WI) clinical data repository.
Coding and statistical analysis
Study population (exposure)
Two sequential reports were created, a baseline “2019” pre-COVID group comprising encounters between 3/15/2019 and 3/14/2020 (the approximate day that COVID restrictions were imposed in Dallas County) and a “2020” post-COVID group representing encounters occurring between 3/15/2020 and 3/14/2021. Only patients with at least one outpatient encounter were included in either group.
We excluded patients with type 2 diabetes, genetic diabetes, cystic fibrosis-related diabetes or secondary (induced by corticosteroids or other drugs) diabetes, and patients with duration of diabetes < 365 days at the time of their most recent encounter.
Covariates
Age was assessed at the last visit of each year. Insurance status was coded as “commercial” (i.e., private-pay or provided by an employer, considered a marker for higher socioeconomic status [7]) or “non-commercial,” (93% of such patients were in government programs, 7% uninsured or “other”, considered to represent lower socioeconomic status). Race and ethnicity were recoded as a single variable with values of “White or Caucasian”, “Hispanic”, “Black or African American”, or “Other”; in our region, the vast majority of Hispanics are of Mexican origin. Patients were classified as continuous glucose monitor (CGM) users if any CGM downloads were present in the database for the given year.
Outcomes
Both inpatient admissions and observations, but not emergency department visits, with ICD-10 codes of E10.10, E10.11, and E10.65 were counted as hospital admissions. Number of office visits during the year was defined as the number of visits to our diabetes clinic with either a physician or a nurse practitioner, excluding education-only group classes. Virtual visits were defined similarly. Our clinic used an Alere Afinion Analyzer (Abbott Diagnostics, Lake Forest, IL) to measure hemoglobin A1c (HbA1c). We used the most recent HbA1c value in each year, which is the only one routinely routinely retained in the database. Values > 15 (i.e., above the linear range of the assay) were recoded as 15. For CGM users, the most recent two-week period available was used to assess time in range. Patients share their Dexcom CGM data with the clinic through the cloud- based Dexcom Clarity application. Freestyle Libre data were shared via Libreview. CGM metrics were documented in the electronic medical record at every visit. Time in range was defined as the proportion of CGM data points falling in the 70–180 mg/dL range. Patient Health Questionnaire-9 (PHQ-9), a self-administered depression screening was offered to all patients with T1D 10 years and older who were seen in person. It was offered every 9 months or sooner if there were mental health concerns. A social worker was consulted if there was a failed screen. The PHQ-9 scores range from 0 to 27. Scores of 5–9 are classified as mild depression; 10–14 as moderate depression; 15–19 as moderately severe depression and ≥ 20 as severe depression.
Statistical analysis
Statistical analysis was conducted in SAS 9.0. Differences in proportions were assessed by Fisher exact tests, and factors influencing continuous variables (HbA1c, CGM time in range, PHQ9 score) were identified using generalized linear models with age, gender, year, insurance status, race/ethnicity and (for HbA1c) CGM use as main effects. Estimates were not adjusted for additional covariates.
We retrospectively assessed whether a previously-developed model of hospitalization risk [6] retained discrimination under the changed circumstances of the pandemic.