Study design
This is a retrospective study describing the HbA1c changes in a patient group that maintained pharmacist visits, with each interval less than 3 months, and in another group, who had a history of a 3-month or longer gap between pharmacist visits. The data were obtained from patients’ electronic medical records during the study period of October 1, 2018, and September 30, 2019, and collected using a HIPAA-compliant, electronic data storage website, REDCap. The institutional review board approval was obtained under HS-19-00929. Patients 18 years and older who were referred by primary care resident physicians for diabetes management, and had 2 or more visits with a pharmacist within the study period, were included. Patients were excluded if they had only 1 HbA1c drawn during the study period, were referred to a pharmacist for reasons other than diabetes management, were concurrently managed by an endocrinologist, had only 1 visit with a pharmacist, or had no visits with their primary care resident physician for over a year. The patients were then divided into 2 groups: continuous care cohort (CCC) and gap in care cohort (GCC). Both face-to-face and phone visits were counted as pharmacist visits for each group.
Outcomes
The primary outcome was the change in HbA1c from baseline between the 2 groups. Baseline HbA1c was considered as the HbA1c value obtained within 3 months prior to, or within 1 month, of the first visit with the pharmacist during the study period. The final HbA1c was considered the value measured within 1 month of, or 3 months after, the patient’s last visit with the pharmacist during the study period.
Several subgroup analyses were conducted to examine the relationship between HbA1c and each group. Among patients whose baseline HbA1c was ≥ 8%, we looked at the percentage of patients reaching HbA1c < 8%, the percentage of patients showing any level of improvement in HbA1c, and the change in HbA1c for each group. We also looked at the percentage of patients with baseline HbA1c < 8% maintaining the level throughout the study period and the change in HbA1c for each group. Additionally, we looked at health care utilization, which included pharmacist visits, primary care physician visits, emergency room and urgent care visits, and hospitalizations for each group. The latter 3 types of utilization were grouped as acute care utilization and further analyzed for visit reasons, which were subsequently categorized as diabetes related and non-diabetes related. The diabetes related reasons linking to acute care utilization were defined as any episodes related to hypoglycemia, diabetic ketoacidosis (DKA), hyperosmolar hyperglycemic state (HHS), foot ulcers, retinopathy, and osteomyelitis infection. All other reasons leading to acute care utilization were categorized as non-diabetes related.
Statistical analysis
Descriptive analyses were conducted using the Mann-Whitney test for continuous data and χ2 (or Fisher exact) test for categorical data. A basic difference-in-differences (D-I-D) method was used to compare the changes of HbA1c between the CCC and GCC over 2 time points: baseline and final measurements. The repeated measures ANOVA was used for analyzing D-I-D. P < .05 was considered significant. Statistical analyses were performed using SAS version 9.4 (SAS Institute, Cary, NC).
Results
Baseline data
A total of 1272 patients were identified within the study period, and 189 met the study inclusion criteria. The CCC included 132 patients, the GCC 57. The mean age of patients in both groups was similar at 57 years old (P = .39). Most patients had Medicaid as their primary insurance. About one-third of patients in each group experienced clinical atherosclerotic cardiovascular disease, and about 12% overall had chronic kidney disease stage 3 and higher. The average number of days that patients were under pharmacist care during the study period was longer in the GCC compared to the CCC, and it was statistically significant (P < .001) (Table 2). The mean ± SD baseline HbA1c for the CCC and GCC was 10.0% ± 2.0% and 9.9% ± 1.7%, respectively, and the difference was not statistically significant (P = .93). About 86% of patients in the CCC and 90% in the GCC had a baseline HbA1c of ≥ 8%.