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The diabetes mellitus cascade of care has been constructed to evaluate diabetes care at a population level by determining the percentage of individuals diagnosed and linked to care as well as their reported glycemic control.
We sought to adapt the cascade of care to an inpatient-only setting using the electronic health record (EHR) data of 81,633 patients with type 2 diabetes.
In this adaptation,
We found that out of 81,633 patients, 28,716 (35.2%) were linked to care via medication prescription. Women and younger patients were slightly less likely to be linked to care than their male and older counterparts, while Black patients (n=19,141, 23.4% of diagnosed population vs n=6741, 23.5% of the linked population) were as proportionately part of the linked population as White patients (n=58,291, 71.4% of diagnosed population vs n=20,402, 71.0% of the linked population). Those living in underserved communities (ie, the Promise Zone) and uninsured patients were slightly overrepresented (n=6789, 8.3% of diagnosed population vs n=2773, 9.7% of the linked population) in the linked population as compared to patients living in wealthier zip codes and those who were insured. Similar patterns were observed among those more likely to reach glycemic control via HbA1c. However, conclusions are limited by the relatively large amount of missing glycemic data.
We conclude that inpatient EHR data do not adequately capture the care cascade as defined in the outpatient setting. In particular, missing data in this setting may preclude assessment of glycemic control. Future work should integrate inpatient and outpatient data sources to complete the picture of diabetes care.
A total of 34 million patients in the United States are currently diagnosed with diabetes mellitus, which equates to roughly 10% of the population. Diabetes was the seventh leading cause of death in 2017. Type 2 diabetes is further complicated by comorbidities, such as high blood pressure, cholesterol, and cardiovascular disease (CVD) [
Overall, new cases of diabetes have been decreasing over the last decade, even among younger patients, while disparities by both race and education level were noted in the US Centers for Disease Control and Prevention’s 2017 diabetes report. The report indicated that Hispanic, Black, and Native American and Alaska Native patients had a higher prevalence of diabetes compared to White patients. Additionally, diabetes was almost twice as prevalent among adults without a high school diploma in contrast to adults who at least graduated and pursued further degrees [
The cascade of diabetes care exists to examine the treatment path from diagnosis to linkage to care for diabetes patients through follow-up visits with their primary care provider, prescription of diabetes medications, and visits with diabetes or nutritional specialists. Diabetes
Using National Health and Nutrition Examination Survey data from 2005 to 2016, previous research found that 70% of patients were linked to care, while just 20% of patients reached the composite treatment targets [
According to the American Diabetes Association (ADA), roughly one-third of health care costs associated with diabetes are related to hospital inpatient care [
Our study population was comprised of 93,433 patients with diabetes who were seen in the inpatient setting of a 15-hospital health care system in St. Louis, Missouri, from 2010 to 2019. We focused our study on individuals with or without complications of diabetes, and we excluded those diagnosed with diabetes during pregnancy (International Classification of Diseases, Tenth Revision [ICD-10] O24.xx, n=3875). Additionally, we excluded patients with type 1 diabetes (ICD-10 E10.xx, n=7925) from our study, given our objective to focus on those diagnosed with type 2 diabetes. We also focused on only those for which the diagnosis of type 2 diabetes appeared in the problem list for that admission. Our final study population included 81,633 patients.
We consulted published guidelines from the ADA [
Patients were considered diagnosed if they had a diagnosis of type 2 diabetes mellitus, with or without complications (ICD-10 E11.xx), and were admitted to the hospital system with their first recorded diabetes diagnosis in the problem list within a day of diagnosis.
Patients were considered linked to care if they were prescribed insulin, noninsulin injectables, or oral anti-diabetes drugs (
Patients were considered controlled if their recorded HbA1c 6 months after discharge was between 7% and 8.5%. This definition was individualized per existing guidelines and the previously published outpatient cascade of care [
Patients less than 65 years of age were considered controlled (HbA1c≤7%) if they had diabetes without complications or CVD, and were considered controlled (HbA1c≤8%) if they had complications or CVD.
Patients 65 years of age or older were considered controlled (HbA1c≤7.5%) if they had diabetes without complications or CVD, and were considered controlled (HbA1c≤8.5%) if they had complications or CVD.
Our population was mainly White, consistent with the population in the St. Louis metropolitan area. Thus, we categorized race into categories of White, Black, and other. We defined age groups according to the following cutoffs: 18 to 44 years, 45 to 64 years, and 65 years of age and older [
We classified the zip code of residence for each patient according to whether or not they lived in the Promise Zone. The Promise Zone is an area in North St. Louis City and County designated in 2015 that is defined by a poverty rate or extremely low–income rate equal to or greater than 33% of the federal poverty level, where a federal local partnership has been established to improve education, economic activity, health, and wellness in the community [
To assess which HbA1c control cutoff to use, we considered patients’ diabetes diagnoses, as well as any CVD diagnoses as previously described, and the patients’ ages. Our definition of CVD included myocardial infarction, heart failure, and angina (
We constructed descriptive statistics of the distributions of race, sex, and age at diagnosis, as well as insurance status, residence in the Promise Zone, and inpatient glycemic care indicators: HbA1c, insulin, and diabetes consultation in our data set. We then compared proportions within each category along the cascade of care to assess disparities using two-sample chi-square tests.
We explored geographic disparities in the data and compared the cascade of diabetes care for patients who lived in Promise Zone zip codes to those residing in the remaining zip codes in the patient catchment area.
We hypothesized that patients living in Promise Zone zip codes and those with self-pay insurance or on Medicaid would be less likely to be linked to care and to reach HbA1c control. Additionally, we hypothesized that patients who had an inpatient glycemic care indicator would be more likely to be linked but less likely to be controlled, as those patients may be more severe cases to begin with to require inpatient insulin treatment. From findings in the previous literature, we hypothesized that women, Black patients, and younger patients would be disproportionately unlinked and uncontrolled [
This study was approved by the Washington University St. Louis Institutional Review Board (IRB) as an “exempt” project. The IRB ID for this project was 202007104.
In our data set, 81,633 patients met the inclusion criteria. Our study population was 48.9% (n=39,880) female, 51.1% (n=41,748) male, and predominately White (n=58,291, 71.4%) and older (≥65 years of age: n=46,860, 57.4%;
Demographic and clinical characteristics of our study population.
Variable | Participants (N=81,633), n (%) |
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Female | 39,880 (48.9) |
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Male | 41,748 (51.1) |
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Missing | 5 (<1.0) |
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White | 58,291 (71.4) |
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Black | 19,141 (23.4) |
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Other | 2625 (3.2) |
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Missing | 1576 (1.8) |
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18-44 | 5887 (7.2) |
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45-64 | 28,886 (35.4) |
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≥65 | 46,860 (57.4) |
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Missing | 4 (<1.0) |
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Residence in Promise Zone | 14,309 (17.5) |
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Private | 28,997 (35.5) |
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Medicare | 31,742 (38.9) |
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Medicaid | 14,096 (17.3) |
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Uninsured or self-pay | 6798 (8.3) |
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Missing | 4 (<1.0) |
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HbA1ca measured within 24 hours | 22,337 (27.4) |
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Insulin lispro administered within 24 hours | 59,220 (72.5) |
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Diabetes or endocrinology specialist consultation during stay | 4988 (6.1) |
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At least one glycemic care marker | 63,222 (77.4) |
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aHbA1c: hemoglobin A1c.
Out of 81,633 patients in our data set, 35.2% (n=28,716) met the linkage-to-care criteria for medication prescription within 3 months of discharge.
This flowchart illustrates the cascade of type 2 diabetes care with cohort sizes at each stage of the cascade, including information about missing glycemic data. Note, the control row of the flowchart indicates the percentage of the linked or unlinked cohorts, not the percentage of the original diagnosed cohort. HbA1c: hemoglobin A1c.
In our data, females and younger patients were less likely to be linked to care compared to males and middle-aged patients. Women made up 48.9% (n=39,880) of the diagnosed population, but 48.9% (n=13,814) of the linked population (<1% change,
Differences in HbA1c control among individuals linked to care must be interpreted with caution in the setting of missing data. Among those linked to care, patients 65 years of age and older and men were less likely to be uncontrolled compared to younger patients and women. Black patients were overrepresented in the uncontrolled group, but they were also less likely to be missing a recorded HbA1c value at 6 months as measured in the inpatient setting. While patients in the Promise Zone were more likely to be linked to care, approximately one-third (n=1612, 30.0% of linked patients residing in the Promise Zone) of those patients reached HbA1c control. Finally, individuals with self-pay insurance and those on Medicaid were less likely to be controlled but were also less likely to be missing HbA1c data over the course of the 6-month follow-up window.
Cascade of care by population covariates.
Variable | Diagnosed (N=81,633), |
Linked to care (n=28,716), |
Unlinked to care (n=52,917), |
Linked to care, n (%)a | |||
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Controlled |
Uncontrolled HbA1c (n=4148) | Missing HbA1c (n=17,492) | |
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Female | 39,880 (48.9) | 13,814 (48.1)* | 26,066 (49.3) | 3592 (50.8)* | 2102 (50.7)* | 8120 (46.4)* |
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Male | 41,748 (51.1) | 14,902 (51.9)* | 26,846 (50.7) | 3484 (49.2)* | 2046 (49.3)* | 9372 (53.6)* |
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Missing | 5 (<1.0) | 0 (0) | 5 (<1.0) | 0 (0) | 0 (0) | 0 (0) |
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White | 58,291 (71.4) | 20,402 (71.0) | 37,889 (71.6) | 4789 (67.7)* | 2584 (62.3)* | 13,029 (74.5)* |
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Black | 19,141 (23.4) | 6741 (23.5) | 12,400 (23.4) | 2012 (28.4)* | 1418 (34.2)* | 3311 (18.9)* |
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Other | 2625 (3.2) | 1001 (3.5)* | 1624 (3.1) | 246 (3.0) | 109 (2.6) | 679 (3.9)* |
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Missing | 1576 (1.8) | 572 (1.9) | 1004 (1.9) | 74 (<1.0) | 32 (<1.0) | 473 (2.7)* |
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18-44 | 5887 (7.2) | 1963 (6.8)* | 2924 (7.4)* | 349 (4.9)* | 516 (12.4)* | 1098 (6.3)* |
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45-64 | 28,886 (35.4) | 10,397 (36.2)* | 18,489 (34.9) | 2376 (33.6)* | 2130 (51.4)* | 5891 (33.7)* |
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≥65 | 46,860 (57.4) | 16,356 (57.0) | 30,504 (57.6) | 4351 (61.5)* | 1502 (36.2)* | 10,503 (60.0)* |
Residence in Promise Zone | 14,309 (17.5) | 5366 (18.7)* | 8943 (16.9)* | 1612 (22.9)* | 847 (28.5)* | 2661 (15.2)* | |
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Private | 28,997 (35.5) | 9611 (33.5)* | 19,386 (36.6)* | 1937 (27.4)* | 1140 (38.4)* | 6145 (35.1)* |
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Medicare | 31,742 (38.9) | 11,487 (40.0)* | 20,255 (38.2)* | 3132 (44.3)* | 731 (24.6)* | 7152 (40.9) |
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Medicaid | 14,096 (17.3) | 4845 (16.9) | 9251 (17.5) | 1261 (17.8) | 583 (19.6)* | 2813 (16.1)* |
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Self-pay | 6798 (8.3) | 2773 (9.7)* | 4025 (7.6)* | 746 (10.5)* | 515 (17.3)* | 1382 (7.9)* |
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HbA1c measured within 24 hours | 22,337 (27.4) | 8255 (28.7)* | 14,082 (26.6)* | 1979 (28.0)* | 1390 (33.5)* | 4886 (27.9) |
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Insulin lispro administered within 24 hours | 59,220 (72.5) | 23,003 (80.1)* | 36,217 (68.4)* | 5589 (79.0)* | 3649 (88.0)* | 13,765 (78.7)* |
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Diabetes or endocrinology specialist during stay | 4988 (6.1) | 2335 (8.1)* | 2654 (5.0)* | 737 (10.4)* | 687 (16.5)* | 910 (5.2)* |
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At least one inpatient glycemic care marker | 63,222 (77.4) | 24,159 (84.1)* | 39,064 (73.8)* | 5937 (83.9) | 3800 (91.6)* | 14,421 (82.4)* |
aProportions in the glycemic control columns denote the proportion of linked patients, not of the entire diagnosed population.
bHbA1c: hemoglobin A1c.
*
Patients with inpatient glycemic care markers were more likely to be linked to care. For example, 72.5% (n=59,220) of the diagnosed population were administered insulin lispro within 24 hours, and those patients made up 80.1% (n=23,003) of the linked cohort versus 68.4% (n=36,217) of the unlinked cohort (
The analysis in this study is a first step in using inpatient EHR data to explore the diabetes cascade of care in an inpatient setting. Among a population of individuals with type 2 diabetes diagnoses newly noted during hospital admission, we were able to determine how many were linked to care using a definition of diabetes medication prescription within 3 months of discharge. We were able to determine indicators of inpatient glycemic management (ie, HbA1c checked, insulin started, or diabetes service consulted) and identified that individuals with one or more of these indicators were significantly more likely to be linked to care. Our findings highlight the importance of recognizing diabetes during a hospital stay in establishing appropriate follow-up.
We observed that a significant proportion of individuals treated with insulin lispro during a hospital stay did not meet criteria for linkage to care, identifying a potential opportunity for intervention. In addition, very few patients were seen by a diabetes or endocrinology specialist in the hospital; however, this is not unexpected given that diabetes consultations, when available at a particular hospital, are typically reserved for only the most severely uncontrolled patients. We also examined HbA1c values at 6 months postdischarge; however, conclusions about control were limited by significant
Our analysis highlights three important points: (1) a possible “leaky pipeline,” or patients that drop out of the cascade of care after discharge from the hospital; (2) the importance of recognizing and acting on diabetes in the inpatient setting to mitigate this leaky pipeline; and (3) the difficulty of using inpatient data alone for the definition of a diabetes cascade of care.
First, we noted that only 35% of the population was linked to care by our definition of receiving medication for diabetes within 3 months of discharge. This likely overestimates loss to follow-up; however, because 19% of patients in the unlinked group were noted to have a controlled HbA1c at 6 months postdischarge, these patients were likely linked to outpatient care. Nonetheless, even if those who were linked to care and those who were unlinked but controlled were considered together, they would comprise 54% of the population. This proportion is much lower than the 77% who met one of the inpatient glycemic care indicators in the inpatient setting.
We observed that patients with at least one of the inpatient glycemic care markers were much more likely to be linked to care than those without, underscoring the importance of recognizing and acting on diabetes during a hospital stay. Additionally, and not surprisingly, at 6 months postdischarge, a larger proportion of individuals who were linked to care had controlled HbA1c as compared to those not linked to care, and a smaller proportion of those who were linked to care had missing HbA1c data as compared to those not linked to care. We hypothesized that while patients with inpatient glycemic care markers were more likely to be linked to care, they would also be less likely to reach their HbA1c target at 6 months, possibly representing diabetes that is more difficult to control.
Counter to our hypothesis, patients with no insurance were more likely to be linked to care, and patients with private insurance were less likely to be linked. Meanwhile, patients living in the Promise Zone were more likely to be linked to care as compared to those not residing in the Promise Zone. These findings were unexpected but could reflect the type of follow-up data available within our hospital system. Privately insured individuals and those living in zip codes with higher economic opportunity may be more likely to follow up with a physician outside of our system, whereas uninsured patients and those living in the Promise Zone may be more likely to be readmitted to our system as an inpatient during the follow-up period.
Data
Overall, our analysis demonstrates that defining a cascade of diabetes care using inpatient data alone is limited by the fragmentation in the health care ecosystem. Given that diabetes is managed almost exclusively in the outpatient setting, the utility of an inpatient diabetes cascade of care would be primarily to (1) determine appropriate management of hyperglycemia in the inpatient setting for individuals with diabetes and (2) identify newly diagnosed diabetes and action by the inpatient team to prescribe appropriate therapy and connect the patient to an outpatient provider upon discharge. Our analysis highlights a challenge commonly encountered in the United States, in that inpatient data may not be linked to outpatient data, even within a network of affiliated outpatient practices in a hospital system [
An optimal investigation of a diabetes cascade of care would focus on diabetes first noted in the inpatient setting and identifying individuals first noted in a hospital stay to have glucose values outside of the normal range. The next steps would be to determine what proportion of these individuals subsequently had an HbA1c evaluation, and then to quantify how many of those diagnosed with diabetes via an HbA1c value equal to or more than 6.5% were initiated on diabetes medication and referred to a primary care provider for follow-up. Such an investigation would also include detailed glucose data during the hospital stay to determine what proportion of individuals with blood sugars greater than 180 mg/dL in the inpatient setting were started on insulin during the hospital stay and how many had a diabetes consultation in the hospital. The cascade would then follow individuals in the outpatient setting to determine how many ultimately achieved glycemic control, blood pressure, cholesterol, and smoking targets, which are associated with CVD risk among patients with diabetes. The benefit of using fully integrated inpatient and outpatient EHR data for this type of analysis lies in the potential for longitudinal follow-up and the opportunity to identify individuals most severely affected by complicated diabetes who are hospitalized.
The lack of interoperability between inpatient and outpatient EHR systems creates significant opportunities for loss to follow-up in clinical care. Hospital discharge summaries may not reach the primary care physician, and they may not specifically address diabetes if this was not the reason for admission [
Significant limitations exist in the study, as outlined in the previous section, in part due to fragmentation. This is evidenced in the high number of missing HbA1c measures due to the limitations of inpatient EHR data that we had access to for the analysis. Additionally, we pulled the first inpatient admission of diabetes mellitus based on the problem list for each patient, which means they could have been diagnosed earlier in the outpatient or primary care setting and received linkage to care for their diabetes in another setting not captured in our analysis.
An inpatient encounter may be an opportunity for incidental diabetes diagnosis, treatment, and linkage to care. However, a cascade of diabetes care using inpatient data alone is insufficient and difficult to align with the outpatient cascade of diabetes care [
Variable definitions using administrative codes.
American Diabetes Association
Center for Diabetes Translation Research
cardiovascular disease
electronic health record
hemoglobin A1c
International Classification of Diseases, Tenth Revision
Institutional Review Board
National Institute of Child Health and Human Development
The project described was supported by the Center for Diabetes Translation Research (CDTR; grant P30DK092950), the National Institute of Child Health and Human Development (NICHD; grant K23096204), and the Faculty Scholarly and Creative Award supported by Drexel University. The content is solely the responsibility of the authors and does not necessarily represent the official views of the CDTR, NICHD, or Drexel University.
None declared.