To evaluate the efficacy of our program before implementing it throughout our practice, we conducted a retrospective cohort study comparing a cohort of patients who received the intervention with those who received usual care during the same time period. This study was approved by the UNC Institutional Review Board.
Intervention patients included all UNC IMC eligible patients discharged after 1 April 2012 who were seen in the hospital follow-up clinic between 2 April 2012 and 31 August 2012, regardless of reasons for admission. Eligible patients were those with an established PCP in the UNC IMC. Exclusion criteria were: discharged to hospice, skilled nursing facility, physical rehabilitation facility, or substance abuse rehabilitation facility; index hospitalization for a scheduled procedure, scheduled infusion, obstetrics, suicidal ideation or discharging service was psychiatry; and patients who left the hospital against medical advice.
Usual care patients were selected from the pool of patients that met the inclusion/exclusion criteria and that were not referred to the hospital follow-up clinic after a discharge. They were selected using a random number generator and were matched to an intervention group patient based on the UNC readmission risk classification (Appendix 1: University of North Carolina General Readmission Risk Stratification, available online) at the time of discharge and had an index discharge within 1 month of the respective intervention patient. Individual patients could be included in both the usual care and hospital follow-up clinic group if the individual was admitted more than once during the study period and the index discharge and subsequent admission were greater than 30 days apart.
Demographic and clinical data were abstracted from inpatient and outpatient encounters in the electronic health record. Comorbid disease state definitions are defined in Appendix 2 (available online).
The primary outcomes were hospital readmission at 30 and 90 days. Secondary outcomes were composites of hospital readmission and ED visits at 30 days and 90 days. ED visits were not counted as separate events if they resulted in a hospitalization. We assessed time to follow-up as a process indicator.
Demographic and clinical data in the intervention group and usual care group were compared using a chi-square test for dichotomous variables and Student’s t-test for continuous variables. Fisher’s exact test was used to compare dichotomous variables with five or fewer individuals in ≥25 % of categories. For continuous variables found to have a non-normal distribution, a Wilcoxon-Mann–Whitney test was used to compare groups.
The time to our primary outcomes of 30-day and 90-day readmissions was compared between intervention and usual care groups with multivariable Cox proportional hazards regression models. We also compared the time to our secondary composite outcomes (30-day and 90-day emergency department [ED] visits and readmissions) between groups. Models were adjusted for covariates that were found to be significantly different between groups in bivariate analyses or had the potential to be a confounder. A sensitivity analysis was performed to address two potential biases: 1) patients whom we attempted, but were unable to contact; and 2) patients who did not attend their scheduled hospital follow-up appointment. The details and results of this analysis are described in Appendix 3 (available online). We considered a two-sided p value of < 0.05 statistically significant. All data analyses were performed using Stata 11.0 (College Station, TX).
Between 1 April and 31 August 2012, we identified 67 hospital follow-up visits. After exclusions, the intervention group included 52 patients with 54 discharges. The usual care group consisted of 52 patients with 54 discharges. Reasons for exclusion are described in Appendix 4 (available online).
The mean age of the study population was 60.9 years; 55 % were female, and 58 % were Caucasian (Table 1). The groups were adequately matched based on readmission risk classification. More women and patients with pulmonary disease were in the intervention group; more patients in the usual care group had cirrhosis or depression. The majority of patients in both groups had insurance, most commonly Medicare. Primary indications for hospitalization were quite variable (Appendix 5, available online).
Primary and Secondary Outcomes: Readmissions, ED Visits, and Composite ED Visits and Readmissions
The intervention group had significantly fewer readmissions at 30 and 90 days. ED visits were also reduced in the intervention group, although not statistically significant. The composite of readmissions and ED visits was significant at 30 and 90 days (Table 2).
Time to Follow-up
Median time to first UNC IMC follow-up was 5 days earlier for patients seen in the hospital follow-up clinic compared to usual care controls (Table 2).
The hazard ratios (HR) for 30-day and 90-day readmissions in the unadjusted model were both lower in the intervention group (HR 0.32, 95 % CI 0.12–0.91; HR 0.34, 95 % CI 0.16–0.72, respectively) (Fig. 3a). When we adjusted for covariates, the association was somewhat attenuated for 30-day readmissions (HR 0.54, 95 % CI 0.17–1.69), but remained statistically significant for 90-day readmissions (HR 0.42, 95 % CI 0.18–0.97).
The HR of 30-day and 90-day composite outcomes of ED visits and readmissions were lower in the intervention group compared with the usual care group in unadjusted models (HR 0.37, 95 % CI 0.18–0.78; HR 0.46, 95 % CI 0.26–0.82, respectively) (Fig.
3b). Adjusting for covariates in both the 30-day and 90-day composite models resulted in minimal changes (HR 0.54, 95 % CI 0.17–1.69; HR 0.42, 95 % CI 0.18–0.97, respectively).