Temporal Shift in Prevalence of Heart Failure Diagnoses and Comorbidities Within 2 US Integrated Health Systems

ABSTRACT

Objective: To assess trends in assigned International Statistical Classification of Diseases, Tenth Revision (ICD-10) codes for patients hospitalized with heart failure (HF) from 2018 to 2022 in 2 large US health systems.

Study Design: Retrospective cross-sectional analysis of ICD-10 codes assigned to patients hospitalized with HF in the Providence Health and University of Colorado Health (UCHealth) systems.

Methods: The study included patients discharged from the Providence Health and UCHealth systems between 2018 and 2022 with a primary diagnosis of HF. ICD-10 codes analyzed included systolic HF (I50.2), diastolic HF (I50.3), combined systolic and diastolic HF (I50.4), hypertensive heart disease with HF (I11.0), and hypertensive heart disease with HF and chronic kidney disease (CKD) (I13.0, I13.2). Hospitalization data were analyzed separately for each health system due to privacy policies.

Results: Between 2018 and 2022, 61,238 HF hospitalizations occurred in the Providence Health system, and 13,576 occurred in UCHealth. Hypertensive heart disease with HF and CKD was the most common diagnosis, accounting for 42% to 56% of HF hospitalizations, followed by hypertensive heart disease with HF (34%-42%). Together, these diagnoses represented 85% to 90% of HF hospitalizations. Systolic, diastolic, and combined HF codes accounted for only 9% to 18% of hospitalizations. Significant variability in hypertension prevalence (ie, 100% in Providence Health and 38%-39% in UCHealth) was observed between the 2 health systems in patients with codes I13.0 and I13.2.

Conclusions: The study highlighted a significant shift in HF diagnosis codes, with hypertensive heart disease with HF with and without CKD now predominant. The findings highlight the need for standardized coding practices across health systems for quality improvement initiatives and health services research.

Am J Manag Care. 2025;31(8):In Press

Takeaway Points

• This study highlights a significant shift in heart failure (HF) diagnoses, with hypertensive heart disease with and without chronic kidney disease now predominant, reflecting changes in International Statistical Classification of Diseases, Tenth Revision coding practices.
• The variability in coding and related comorbidities rates between health systems could impact the accuracy of HF prevalence and may reflect institutional billing conventions.
• The findings emphasize the importance of standardized coding practices to ensure consistency in care quality and health services research.

Heart failure (HF) is a major cause of morbidity and mortality. By 2030, it is projected that approximately 8.5 million individuals in the US will have HF, with an expected overall cost of $70 billion.¹ Although current guidelines recommend that patients with HF be classified by stage and left ventricular ejection fraction,^2,3 International Classification of Diseases diagnosis codes are routinely assigned to these patients in different health care settings. Historically, a limited number of International Statistical Classification of Diseases, Tenth Revision (ICD-10) codes (eg, systolic HF, diastolic HF, and combined systolic and diastolic HF) have been used to characterize most patients hospitalized with HF.⁴ In 2017, however, a significant shift in assigned ICD-10 codes was observed nationally, with codes for hypertensive heart disease with HF and hypertensive heart disease with HF and chronic kidney disease (CKD) increasing appreciably.⁵ Because the prevalence of these comorbidities (hypertension and CKD) may vary across US health systems, we sought to assess trends in assigned ICD-10 codes among patients hospitalized for HF from 2018 to 2022 in 2 large integrated health systems serving geographically diverse populations.

METHODS

This retrospective cross-sectional analysis included patients discharged from the Providence Health and University of Colorado Health (UCHealth) systems between 2018 and 2022 with a primary diagnosis of HF. ICD-10 codes assigned as the primary discharge diagnosis included I50.2 (systolic HF), I50.3 (diastolic HF), I50.4 (combined systolic and diastolic HF), I11.0 (hypertensive heart disease with HF), and I13.0 and I13.2 (hypertensive heart disease with HF and CKD [ie, stage 1-4 for I13.0 and stage 5 or end stage for I13.2]). Hypertension was defined by ICD-10 codes as previously described.⁵ CKD was defined as an estimated creatinine clearance less than 60 mL/min using the 2021 CKD-EPI equation based on predischarge laboratory data. The Providence Health system includes 51 hospitals in Alaska, California, Montana, Oregon, Texas, and Washington; UCHealth includes 17 hospitals in Colorado, Nebraska, and Wyoming.

Patient-level analyses were not performed; all hospitalizations were considered independent events. Data from the health systems were analyzed separately due to policies related to institutional privacy. The primary ICD-10 code associated with each hospital encounter was tabulated. The selected time frame extends previously published findings using data related to hospitalizations through 2018.⁵ The study was approved by the Providence Institutional Review Board and the Colorado Multiple Institutional Review Board with waivers of informed consent.

RESULTS

Between 2018 and 2022, 61,238 and 13,576 HF hospitalizations occurred in the Providence Health and UCHealth systems, respectively. In both health systems, hypertensive heart disease with HF and CKD was the most common ICD-10 diagnosis, accounting for 42% to 56% of hospitalizations (52%-56% in the Providence Health system and 42%-46% in the UCHealth system) (Figure, panels A and B, respectively). Hypertensive heart disease with HF was the next most common ICD-10 diagnosis, accounting for more than one-third of hospitalizations (34%-39% in the Providence Health system and 38%-42% in the UCHealth system). Collectively, these 2 groups of ICD-10 diagnoses (I13.0 + I13.2 and I11.0) accounted for approximately 85% to 90% of HF hospitalizations. By comparison, systolic HF, diastolic HF, and combined systolic and diastolic HF comprised only 9% to 18% of HF hospitalizations. Little change in assigned ICD-10 codes was observed over time. Among hypertensive heart disease with HF and hypertensive heart disease with HF and CKD encounters in the Providence Health system, 100% had a diagnosis of hypertension; in contrast, only 39% and 38% of encounters at UCHealth had a diagnosis of hypertension, respectively. Among hypertensive heart disease with HF and CKD encounters, concurrent CKD was found in 94% of encounters in the Providence Health system and almost 100% at UCHealth.

DISCUSSION

In this analysis of HF ICD-10 codes assigned at discharge for 2 large US health care systems, hypertensive heart disease with HF and CKD and hypertensive heart disease with HF were the 2 HF diagnoses most often assigned. These patterns persisted over time, with systolic, diastolic, and systolic and diastolic HF accounting for a small proportion of diagnoses. This is despite considerable variability in hypertension coding between the 2 health systems among encounters classified as hypertensive heart disease with HF and hypertensive heart disease with HF and CKD.

These observations are consistent with a previously noted shift in HF diagnosis codes between 2016 and 2018 using Medicare fee-for-service administrative claims.⁵ In that analysis, a substantial increase in ICD-10 codes corresponding to hypertensive heart disease with HF and CKD and hypertensive heart disease with HF was noted, increasing from 26% of total codes in 2016 to 84% in 2017 to 90% in 2018.⁵ We noted persistence of this pattern using our all-payer data set, with hypertensive heart disease with HF and CKD and hypertensive heart disease with HF accounting for approximately 90% of discharge diagnoses in 2022. The prevalence of hypertensive heart disease with HF and CKD was higher in Providence Health than in the UCHealth system. Observed differences between the health systems may relate to variation in patient demographics or health characteristics, clinician documentation practices, and coding policies by the 2 organizations. Of note, in the previous analysis using Medicare data between 2016 and 2018, hypertension was noted in 83% to 85% of patients with hypertensive heart disease with HF and hypertensive heart disease with HF and CKD. Likewise, renal failure was noted in almost 100% of patients with hypertensive heart disease with HF and CKD.⁵

Changes in the pattern of assigned codes likely reflect changes to CMS coding rules that took place in 2017.⁶ The guidelines on these coding rules note that there is an inferred “causal relationship between hypertension and heart involvement and between hypertension and kidney involvement.”⁶ These associations are even more fully reinforced in the 2023 American Heart Association Presidential Advisory on Cardiovascular-Kidney-Metabolic Health, in which cardiovascular-kidney-metabolic syndrome is defined as “a health disorder attributable to connections among obesity, diabetes, CKD, and cardiovascular disease (CVD), including heart failure, atrial fibrillation, coronary heart disease, stroke, and peripheral artery disease.”⁷ Although our analysis highlights the high prevalence of CKD in patients hospitalized with hypertensive heart disease with HF and CKD, significant differences in the rate of concurrent hypertension exist in the 2 health systems among those hospitalized with hypertensive heart disease with HF with or without CKD. The reasons for this are not known but may reflect institutional billing conventions.

Research opportunities exist to improve coding standardization for HF encounters across health systems. A detailed coding guideline may include specific instructions for different HF phenotypes and concomitant comorbidities related to ICD-10 codes. Moreover, provider training is needed to accurately code HF encounters. Furthermore, data audits may assist in maintaining high quality standards in ICD-10 code classification. Finally, a standard reimbursement model could reduce further differences based on institutional conventions. Taken together, these opportunities may harmonize HF classification coding and data collection for research purposes by multicenter registries.

Limitations

This study has multiple limitations. First, because the cohort was defined exclusively by ICD-10 codes, it is possible that the primary reason for hospitalization was misclassified as HF. Second, the analysis did not include information related to HF type (eg, HF with reduced ejection fraction, HF with mildly reduced ejection fraction, HF with preserved ejection fraction). Previous analyses have suggested more limited correlation between HF type and electronic health record–derived ICD-10 codes, at least in the ambulatory setting.⁸ Finally, although this analysis included a large patient cohort representing geographically diverse populations, it is possible that the findings presented may not be generalizable to other health care systems.

CONCLUSIONS

Among patients hospitalized for HF, a significant shift in assigned ICD-10 codes has taken place. Hypertensive heart disease with HF and CKD and hypertensive heart disease with HF now represent the predominant HF diagnoses across payers. In contrast, ICD-10 codes corresponding to systolic HF, diastolic HF, and combined systolic and diastolic HF now represent only approximately 10% of HF hospitalizations. Notable differences in the prevalence of hypertension were also found for the 2 health systems among those hospitalized with hypertensive heart disease with HF with or without CKD. Collectively, these findings have important implications for HF quality improvement initiatives and health services research that utilize ICD-10 codes.

Acknowledgments

Ty J. Gluckman, MD, MHA; and Marc P. Bonaca, MD, MPH, contributed equally to this work and are listed as co–senior authors. This work was supported by the Health Data Compass Data Warehouse project.

Author Affiliations: CPC Clinical Research (MEC, JH, BP, YHC, MPB), Aurora, CO; Department of Medicine, University of Colorado (MEC, JH, MPB), Aurora, CO; Center for Cardiovascular Analytics, Research, and Data Science (CARDS), Providence Heart Institute of Oregon, Providence Health System (STC, JDR, TJG), Portland, OR; University of Arizona College of Medicine (PKT), Tucson, AZ; Providence Sacred Heart Medical Center, Providence Health System (JOM), Spokane, WA.

Source of Funding: This work was supported by Lexicon Pharmaceuticals, Inc.

Author Disclosures: Dr Canonico, Dr Hsia, Ms Patel, Dr Chuang, and Dr Bonaca receive salary support from CPC Clinical Research, a nonprofit academic research organization affiliated with the University of Colorado; Dr Hsia also owns stock in AstraZeneca. Dr Remick has received lecture fees from Boehringer Ingelheim for speaking on empagliflozin. Dr Gluckman is a member of the board of the American Society for Preventive Cardiology and consultant for OptumRx. The remaining authors report no relationship or financial interest with any entity that would pose a conflict of interest with the subject matter of this article.

Authorship Information: Concept and design (MEC, PKT, TJG, MPB); acquisition of data (MEC, BP, YHC, TJG); analysis and interpretation of data (MEC, JH, STC, PKT, JOM, JDR, BP, YHC, TJG); drafting of the manuscript (MEC, STC, JOM, JDR, TJG); critical revision of the manuscript for important intellectual content (JH, JOM, JDR, TJG, MPB); statistical analysis (STC, BP, YHC); provision of patients or study materials (MEC, TJG, MPB); obtaining funding (JH, MPB); administrative, technical, or logistic support (MEC, JH, PKT, TJG); and supervision (TJG, MPB).

Address Correspondence to: Mario Enrico Canonico, MD, PhD, CPC Clinical Research and University of Colorado, 2115 N Scranton St #2040, Aurora, CO 80045-7120. Email: marioenrico.canonico@cpcmed.org.

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