Comparing the cost of cirrhosis to other common chronic diseases: A longitudinal study in a large national insurance database

Data Availability - Comparing the cost of cirrhosis to other common chronic diseases: A longitudinal study in a large national insurance database 

Data Availability 

The claims data used for this publication is stored in a secure portal, the UnitedHealth Group (UHG) Enclave, and is accessible only by those with prior authorization to view the data (Table D1). This data is only available to those who have signed Data Use Agreements (DUA) and have undergone training on accessing the data. All statistical analyses were performed using Stata 14.1. 

Table D1: Access to Enclave 

Study Methods 

A retrospective, longitudinal cohort study was conducted between January 1, 2011, and December 31, 2020, by using claims data from UHG, a large national insurer in the United States. The study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cohort studies. The Northwestern University Institutional Review Board deemed this study exempt from review and waived the need for patient-informed consent. The database included deidentified medical and pharmacy claims data for enrollees. Available data included claims for all medical services and prescription medications that were submitted to the insurer for payment, patient diagnoses, and, when available, linked laboratory results. For this study, all enrollees were defined and reported as patients. 

Patients enrolled in non-health maintenance organization (HMO), Medicare Advantage (MA) plans between January 1, 2011, and December 31, 2020, were included in the analysis. Because provider fees under HMO plans/capitated contracts are not available in large insurer data sets, this study focused on patients covered under non-HMO plans (ie, non-capitated claims). Previously validated and published codes were used. Patients diagnosed with cirrhosis were defined as those with at least 1 claim specifying a validated cirrhosis code from the International Classification of Diseases, 9th Revision (ICD-9) or 10th Revision (ICD-10) (571.2, 571.5, 571.6, K70.30, K70.31, K74.0, K74.60, K74.69, K74.3, K74.4, and K74.5), in any position on the claim (Supplemental Figure S1).  

Cirrhosis etiologies were defined by at least 1 claim specifying an ICD-9 or -10 code for: alcohol-associated (ETOH), metabolic dysfunction–associated steatohepatitis (MASH, previously NASH), HBV, HCV, biliary cirrhosis (eg, primary sclerosing cholangitis and primary biliary cirrhosis), cardiac cirrhosis, genetic cirrhosis (eg, hereditary hemochromatosis), and autoimmune hepatitis. Patients were included in the HCV cohort even if they had multiple etiologies, any one of which was HCV.

Other etiologies were analyzed separately unless otherwise specified. Of note, MASH/NASH did not have a dedicated ICD code before October 1, 2015. For data before October 1, 2015, MASH/NASH was identified using a previously published algorithm (patients without specific cirrhosis etiology plus obesity, dyslipidemia, diabetes, and/or hypertension). Patients were categorized into 5 mutually exclusive groups by etiology: MASH, ETOH (which includes alcohol-associated liver disease and metabolic dysfunction–associated steatotic liver disease with increased alcohol intake), HCV, biliary (primary biliary cirrhosis and primary sclerosing cholangitis), and “Other” (eg, hemochromatosis). Validated ICD-9/-10 codes were used to define comorbidities and quantify the Charlson Comorbidity Index. 

To provide a tangible comparison, costs associated with cirrhosis were compared with costs associated with HF and COPD. Patients with HF and COPD were identified by ICD-9/-10 codes as previously published. A sample of these patients was included in the cohort as detailed in Supplemental Figure S1, and the Supplemental Appendix. 

Analyses were performed at the patient-month level. Costs are reported per patient-month unless otherwise specified. For patients with cirrhosis, the index date was the earliest listed date of service on a claim with a diagnosis of cirrhosis or cirrhosis decompensation. For patients with HF and COPD, the index date was the earliest listed date of service on a claim for the appropriate corresponding diagnosis. Diagnoses on claims were defined and identified by validated inclusion ICD codes. If the index code for a patient with cirrhosis indicated decompensation, the patient was considered to be decompensated at the time of inclusion. To most closely represent the epidemiological reality, cirrhosis, HF, and COPD were not considered mutually exclusive. All months of coverage for all included patients under non-HMO MA plans, including and following the index month until the end of observation, were analyzed. The end of observation was defined as disenrollment, transplant, or the end of the cohort study period (December 31, 2020). In the case of a patient receiving a transplant, the entire month of transplantation was censored.

Months of coverage were subcategorized into compensated and decompensated cirrhosis patient-months. The date of decompensation was defined as the date of service on the first claim under any plan that listed an ICD or CPT code for a decompensation event (ie, ascites, spontaneous bacterial peritonitis, HE, variceal bleeding, hepatorenal syndrome, or hepatopulmonary syndrome) (see the Supplemental Appendix). Patients were considered to have decompensated cirrhosis starting from and including the month of the decompensation date until the end of observation. The total number of patient-months with compensated cirrhosis was calculated from the index month until the decompensation month. Inpatient costs were calculated by identifying claims between admission and discharge. The same method of categorizing months of coverage was applied to decompensated HF and exacerbated COPD. Decompensated HF and exacerbated COPD were defined as inpatient admissions with the corresponding condition as the primary diagnosis. 

Cost was defined as the total amount paid by the insurer and patient, taking the health care sector cost perspective. These data were analyzed and reported over time using mean costs in a specific calendar month during the study period. Data reported per patient-year were estimated by multiplying patient-month data by 12. Following common practice, denied service lines were excluded from cost calculation. Average costs were adjusted for inflation to 2021 US dollars using the Bureau of Labor Statistics consumer price index to adjust for inflation between 2011 and 2020. Mean costs were reported with corresponding standard deviations (±SD). Comparisons between relevant subgroups were performed using unequal variance, 2-sided Student t tests. Contained in the Supplemental Appendix is a discussion of the process of generating the patient data and the assumptions underlying the standard inference methods. To identify predictors of increased cost, a multivariable linear regression model of costs for patients with cirrhosis was performed. The outcome of interest was the cost per patient per month, which was modeled continuously. The reference group was non-female patients with ETOH. All statistical analyses were performed using Stata 14.1.