Prevalence and Persistence of Cost-related Medication Non-adherence Before and During the Covid-19 Pandemic Among Medicare Patients at High Risk of Hospitalization

James X. Zhang , David O. Meltzer


To study cost-related medication non-adherence (CRN) for a 30-month period before and during the COVID-19 pandemic using a sample of Medicare patients at high risk of hospitalization.


Non-adherence to medication due to cost is a serious challenge in the US healthcare system, as one in four adults in the US have a difficult time affording their medications [1]. The COVID-19 pandemic has imposed an unprecedented burden on patients regarding seeking and remaining engaged in care. For high-need, high-cost resource utilization populations, such challenges may be particularly pronounced, as they require frequent care and many medications despite limited economic means. It is conceivable that economic pressures coupled with disrupted continuity of care may have affected their medical adherence. In the meantime, government policies to stabilize income and housing (including the Coronavirus Aid, Relief and Economic Security (CARES) Act, providing Americans with expanded unemployment insurance (UI) benefits if they’re out of work for pandemic-related reasons [2], and a temporary national moratorium on most evictions for nonpayment of rent [3]) may have helped patients at the very bottom of the economic ladder to ease the tension between their medical and other basic needs.

Materials and method

We used a sample of Medicare patients at high risk of hospitalization, a high-need, high-cost resource utilization population, who were hospitalized at least once in the previous year or cared for at the emergency department at the time of enrolled into a randomized controlled trial to study the Comprehensive Care Physician (CCP) model, where the CCP integrated the physician services for ambulatory care and inpatient care for patients at high risk of hospitalizations with ongoing quarterly surveys of patients in an urban academic medical center [5, 6]. CRN questionnaire is an original part of the CCP study to advance the understanding of cost barriers to health care. The CCP study is a longitudinal study with the subjects followed up quarterly since enrollment, and follow-up is still ongoing. Medicare is a federal program providing health insurance to 65 million Americans aged 65 or older, under age 65 with certain disabilities, and people of all ages with End-Stage Renal Disease [7]. While the program is heavily subsidized, beneficiaries incur out-of-pocket payments for deductible, co-insurance, and premiums. In traditional Medicare, most beneficiaries’ spending does not exceed $5,000, but 4.5 million people spend over $5,000 per year out-of-pocket and 1.6 million beneficiaries spend $10,000 or more annually [8]. For context, the national average spending per person in Medicare was $15,300 in 2021 [9].


The original CCP study has a sample size of 2000 subjects with 1000 subjects in each study arm and enrollment took place between November 2012 and June 2016. After removing 12 subjects who were randomized in error or withdrawn by patients from the study, we were able to link 1976 (99.4%) subjects out of 1988 successfully to the Medicare enrollment file, with correct linkage ascertained through matching birthdates between our internal survey and Medicare Vital Statistics. Among those 1976 subjects, 721 (36.5%) were ascertained to be deceased before January 1, 2020, through Medicare Vital Statistics, hence were excluded from the study. Those patients were deceased before the pandemic and thus a pre- and during pandemic comparison is not possible.


To our knowledge, this is the first study on cost-related medication non-adherence longitudinally following a sample of high-need, high-cost resource utilization Medicare patients before and during the pandemic. We found that despite increased economic pressure and disrupted medical care, there was a reverse of trend in CRN rates, with significant declining in prevalence and persistence in CRN during the pandemic when compared to the pre-pandemic period.


In summary, we presented coherent evidence of a reversal of CRN rates during the COVID-19 pandemic among this high-need, high-cost resource utilization Medicare population. It demonstrates that patients’ CRN behaviors may be responsive to exogenous impacts, and that behaviors changed in the same direction with similar magnitude in terms of prevalence (the extensive margin) and persistence (the intensive margin). More research is critically needed to advance understanding of the driving forces behind patients’ behavioral changes and to identify factors that may be informative for reducing CRN in the long run.

Citation: Zhang JX, Meltzer DO (2023) Prevalence and persistence of cost-related medication non-adherence before and during the COVID-19 pandemic among medicare patients at high risk of hospitalization. PLoS ONE 18(8): e0289608.

Editor: Tae-Young Pak, Sungkyunkwan University School of Social Sciences, REPUBLIC OF KOREA

Received: January 1, 2023; Accepted: July 22, 2023; Published: August 29, 2023

Copyright: © 2023 Zhang, Meltzer. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: The data contain potentially identifying or sensitive patient information, and restriction of public use of data is imposed by the The University of Chicago IRB and the Data User Agreement with the Centers of Medicare and Medicaid Services. Direct, non-author contact information for the body imposing the restrictions upon the data, to which data access requests can be sent: Michael R. Ludwig,

Funding: This research was funded in part by NIH NIA grant P30AG066619 (DOM and JXZ), a Chicago Center for Diabetes Translation Research (CCDTR) Pilot and Feasibility Grant (JXZ & DOM) (P30DK092949). The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Competing interests: Dr. Meltzer reported receiving compensation from CVS Consultant outside the submitted work. No other disclosures were reported. There are no patents, products in development or marketed products associated with this research to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

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