ROI
The cost savings per DEP patient are shown in Table 5 . The annual cost for a CHW to educate 1 DEP patient was $403. The combined inpatient and ED cost savings for DEP patients post-program enrollment was $137 per patient. ROI for the DEP was –66%, indicating that DEP investment costs were greater than the savings achieved through the reduction of inpatient and ED costs for DEP patients.
Discussion
In our examination of the impact of the DEP on inpatient and ED utilization, we found that DEP patients experienced a significant decrease in inpatient visits, LOS, and direct costs in the year following DEP enrollment. In comparison, a control group of patients who were treated at the same clinics as DEP patients also experienced significant decreases in inpatient LOS and direct costs. No significant differences in ED visits, LOS, or direct costs were observed for either DEP patients or control patients in the post period.
The reduction in inpatient visits and LOS for DEP patients in the year following DEP enrollment indicates that the DEP helped patients achieve improved health and avoid costly hospitalizations. The control group did experience greater reductions in inpatient utilization, LOS, and direct costs. However, because this was not designed as a controlled trial, we utilized a nonequivalent control group and inherent differences between the DEP and control patients and utilization patterns made it difficult to draw unbiased comparisons between the groups. For instance, the number of inpatient encounters, LOS, and costs were 2 to 3 times higher in the pre-period for the control group. The mean number of inpatient encounters for DEP patients prior to DEP participation was 0.18, and the smaller change observed in utilization for DEP patients is likely due to a floor effect.
Despite the observed reductions for both DEP patients and the control group in inpatient utilization, neither group had significant reductions in ED visits or costs per patient in the post- period. The majority of ED use in the pre-period may have been due to diabetes-related complications that are difficult to prevent even with improved diabetes care or for emergencies not related to diabetes, as we included all ED admissions regardless of admitting diagnosis. In addition, similar to observed trends in inpatient utilization, ED use in the pre-period was relatively low for DEP patients (0.16), and the lack of observed changes in ED utilization for DEP patients was also likely due to a floor effect.
The DEP generated a negative ROI (–66%) in the short term as the annual cost savings generated per patient from reduced utilization ($137) were less than the annual DEP costs (investment) per patient ($403). This finding is not surprising, as it is difficult to achieve cost savings for interventions designed to increase access to health care in underserved populations.[15] Although Fedder et al. observed an average savings of $2245 per patient per year in Medicaid reimbursements for a CHW-led outreach program for patients on Medicaid with diabetes, patients who participated in this program had much higher inpatient encounters (0.95 vs. 0.18) and ED utilization (1.49 vs. 0.16) at baseline compared to DEP patients. DEP patients may not have been as sick as these patients or have been more reluctant to seek medical care due to their lack of insurance. In addition, Fedder et al did not factor in the costs of the CHW program in the cost savings calculation. However, these costs were likely to be much lower than the costs of the DEP, as the program relied on volunteer CHWs instead of paid CHWs who were also certified medical assistants.