As the world marks a century since insulin’s discovery, it is important to highlight key trends in a group of patients who are dependent on it for life. Patients with type 1 diabetes require exogenous insulin to avoid complications, including diabetes ketoacidosis (DKA). This condition often first manifests in childhood. The use of technology, including continuous glucose monitors and insulin pumps, is recommended in these patients (1). There have been increasing concerns about the affordability of insulin even in developed countries. This has been associated with recurrent episodes of DKA (2). This study assessed whether there was a variation in readmissions in the pediatric population with DKA by household income in the U.S.

This was a retrospective interrupted trend study involving pediatric hospitalizations for DKA in the U.S. We extracted data from the Nationwide Readmissions Database (NRD) for 2010, 2012, 2014, 2016, and 2018. The NRD is the largest publicly available all-payer inpatient health care readmission database in the U.S., drawn from the Agency for Healthcare Research and Quality Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases (3). The NRD is coded using the 9th and 10th revisions of the International Classification of Diseases (ICD) codes.

The study involved hospitalizations from each studied year of the NRD with DKA as the reason for index admission using ICD codes (E10.1X, 250.11, and 250.13). We excluded hospitalizations in patients older than 18 years. Using unique hospitalization identifiers, index hospitalizations were identified, and one subsequent hospitalization within 30 days was tagged as readmission. We excluded elective and traumatic admissions and readmissions. The NRD includes variables on patient demographics, including age, sex, median household income (MHOI), and primary payer. The income quartiles referred to patients as low income (1), middle income (2), upper middle income (3), and high income (4). We assessed the comorbidity burden using Sundararajan et al.’s (4) adaptation of the modified Deyo-Charlson comorbidity index. This modification groups Deyo-Charlson comorbidity index values into four categories in increasing risk for mortality.

The study outlined the biodemographic trends in pediatric DKA hospitalizations within the study period. We compared trends in 30-day all-cause readmission (30ACR) and DKA-specific readmission rates (30DSR) across the four income quartiles. All analyses were conducted using the weighted samples for national estimates according to HCUP regulations for using the NRD. We used multivariate logistic trend analysis to calculate odds of trends in 30ACR and 30DSR, adjusted for age and sex. All P values were two sided, with 0.05 set as the threshold for statistical significance.

The NRD lacks patient identifiers. In keeping with other HCUP databases, the NRD does not require Cook County Health Institutional Review Board approval for analysis.

Over the study period, the mean age of children readmitted following DKA was 15.3 (SD 3.0) years with no significant variation by MHOI. Females had a higher proportion of readmissions (62.1%) overall. There was a significant increase in female readmissions across MHOI, with 58.4% in the lowest quartile, rising to 73.4% in the highest quartile (P = 0.006). There was no significant variation in age distribution and comorbidity burden by MHOI.

Patients in the lowest income quartile had the highest rates of 30ACR and 30DSR (Fig. 1). There was a trend toward decreasing readmissions with higher MHOI. Compared with the highest income quartile, patients in the lowest quartile had a 78.7% increased odds of being readmitted for DKA and 76.6% increased odds of all-cause readmission in the 30 days following an index hospitalization, adjusted for age and sex (P < 0.001 and P < 0.001, respectively).

Figure 1

Trends in 30DSR by median household income quartile among pediatric hospitalizations for diabetic ketoacidosis. qrtl, median household income quartile for ZIP code.

Figure 1

Trends in 30DSR by median household income quartile among pediatric hospitalizations for diabetic ketoacidosis. qrtl, median household income quartile for ZIP code.

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Despite the similarity in age and comorbidity burden of the population, children from the lowest income quartile had higher rates of readmission following hospitalization for DKA. The persistence of this trend over the past decade is worrying. The MHOI is likely associated with access to health care facilities, medications, follow-up services, and patient and caregiver education level. These factors play a significant role in the management of diabetes and its complications. The study suggests a significant economic disparity in outcomes among children with type 1 diabetes who are more likely to be admitted with DKA. In the pediatric population, increased readmissions could translate to lost school time as well as work time for caregivers, increased exposure to hospital-acquired infections, and increased cost of health care utilization. Ironically, the lowest-income household seems to be the most adversely affected.

We advocate for policies to make insulin in particular and holistic health care in general available for individuals with diabetes who are prescribed insulin, especially those with type 1 diabetes, irrespective of household income. This might bridge the divide identified in this study.

Duality of Interest. No potential conflicts of interest relevant to this article were reported.

Author Contributions. H.S. is solely responsible for the conception, data analysis, and drafting of this article. H.S. is the guarantor of this work and, as such, had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

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