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New Study Suggests Increasing Prescription Co-payments for Chronic Diseases May Worsen Health Disparities, Adversely Affect Health

New Study Suggests Increasing Prescription Co-payments for Chronic Diseases May Worsen Health Disparities, Adversely Affect Health

Published 08-19-08

Submitted by GSK

PHILADELPHIA, Aug. 19 /PRNewswire-FirstCall/ -- The relationship between medication adherence and income level may contribute to the disparities in health observed across socioeconomic groups, according to a recent study published in the Journal of General Internal Medicine. The study, funded by GlaxoSmithKline (NYSE: GSK),investigated whether individuals who reside in low-income areas are more strongly influenced by rising prescription drug co-payments than individuals residing in higher income areas.

Effects of Increased Patient Cost Sharing on Socioeconomic Disparities in Health Care was a multi-year retrospective analysis of insurance claims data for patients with Type 2 diabetes or congestive heart failure (CHF). The analysis showed an inverse relationship between co-payment and medication adherence for most -- although not all -- of the medication classes. Patients in low-income areas were more sensitive to co-payment changes than patients in high- or middle-income areas.

For this analysis, income categories were established using zip code based income measures as a proxy for individual income. The income categories were as follows: under $30,000; $30,000 to $42,000; $42,000 to $62,000; and more than $62,000.

The occurrence of disparities in health and healthcare utilization across US socioeconomic groups has been well documented. The research suggests that low-income individuals with chronic diseases, such as diabetes and CHF, have poorer adherence rates -- and they may be less likely to use recommended medications and procedures to manage their conditions -- than their more affluent counterparts.(1,2,3,4,5)

Study Details
A total of 29,764 patients with diabetes and 13,081 with CHF met the criteria for inclusion in the study. Among the diabetes patients, the average age was 53 years, and 44.4% were female; CHF patients were more likely to be older (56.5 years). Mean co-payments were $19 for brand-name drugs and $8 for generic drugs per 30-day supply. For those employers that changed co-payments during the study period, increases in co-payments ranged from $0 to about $13.00, with an average of about $4.50.

Key findings of the study included:

  • Results suggest that for each medication class, individuals in high-income areas were consistently more adherent than individuals in low-income areas.
  • For both diabetes and CHF, there was a notable decrease in medication adherence across all drug categories in response to a 10% increase in drug co-payment, with the largest decreases in adherence occurring in the lowest income groups.
  • Adherence to statins was particularly sensitive to income, with diabetes patients in the highest-income group being more than 20% more adherent than those in the lowest-income category.
  • In high-income areas, CHF patients were over 30% more adherent to statins than their counterparts in low-income areas. CHF patients in high-income areas were also substantially more adherent to beta-blockers than CHF patients in low-income areas.
The study was co-authored by Michael Chernew, PhD (Harvard Medical School); Teresa B. Gibson, PhD (Thomson Healthcare); Kristina Yu-Isenberg, PhD, RPh and Michael C. Sokol, MD, MS (GlaxoSmithKline); Allison B. Rosen, MD, ScD and A. Mark Fendrick, MD (Schools of Medicine and Public Health, University of Michigan).

Medication Adherence is Essential to Managing Chronic Diseases
Adherence to medications is an important factor in clinical outcomes for patients with chronic diseases. Poor adherence is a serious problem, contributing to substantial worsening of disease, complications, death, and increased healthcare costs.(6) Therefore, improving medication adherence can be an important step in improving health for those with chronic diseases. In some cases, greater medication adherence may even result in lower total medical expenditures.(7)

While the impact of cost-sharing on medication adherence, and in particular of increasing medication co-payments, has been shown to decrease use of medications for chronic conditions,(8,9,10) these studies have not specifically addressed the effect of income on utilization.

"Based on our analysis, it is likely that increased co-payments, intended to control costs, will exacerbate the disparities seen across socioeconomic groups," said Michael Chernew, PhD, professor, Department of Health Care Policy, Harvard Medical School.

The current study complements the results of earlier studies from GSK's Health Management Innovations team, which indicate that barriers to medication access should be removed to improve adherence, better manage chronic conditions, improve health -- and lower total healthcare costs. These studies, read in the context of the body of literature on medication adherence, suggest that value-based health management can lead to better adherence -- and better outcomes for both patients and employers.

"We must encourage employers and health plans to develop benefit strategies that improve the health of all patients -- especially those with chronic diseases -- which can lead to lower total healthcare costs," said Michael C. Sokol, MD, MS, medical director for GSK's Health Management Innovations team.

The Real Driver of Healthcare Costs -- Chronic Diseases
Today's greatest healthcare threats are chronic conditions, which require ongoing, patient-centered management. In fact, $3 of every $4 spent on healthcare in the US(11) goes to treating the 45% of Americans with at least one chronic disease.(12) As well, according to the Milken Institute, the seven most common chronic diseases cost the US economy $1.3 trillion each year -- including both direct and indirect costs.(13)

While employers have often implemented strategies of shifting costs onto the patient, this is only a short-term economic fix. To lower overall healthcare costs and improve the health of patients of every socioeconomic group, the focus must be on the driver of healthcare costs in the US -- chronic diseases.

About GlaxoSmithKline
GlaxoSmithKline, one of the world's leading research-based pharmaceutical and health care companies, is committed to improving the quality of human life by enabling people to do more, feel better, and live longer.

To learn more about value-based health management, visit the Center for Value-Based Health Management at

For the complete study, please visit (due to the length of this URL, please copy and paste it into your web browser)

(1) Rao SV, Kaul P, Newby LK, et al. Poverty, process of care, and outcome in acute coronary syndromes. JACC. 2003;41(11):1948-54.
(2) Lemstra M, Neudorf C, Opondo J. Health disparity by neighbourhood income. Can J Public Health. 2006;97(6):435-9.
(3) Schneeweiss S, Soumerai SB, Glynn RJ, Maclure M, Dormuth C, Walker AM. Impact of reference-based pricing for angiotensin-converting enzyme inhibitors on drug utilization. CMAJ. 2002;166(6):737-45.
(4) Federman AD, Halm EA, Zhu C, Hochman T, Siu AL. Association of income and prescription drug coverage with generic medication use among older adults with hypertension. Am J Manag Care. 2006;12(10):611-8
(5) Piette JD, Heisler M, Wagner TH. Problems paying out-of-pocket medication costs among older adults with diabetes. Diabetes Care. 2004;27(2):384-91.
(6) Osterberg L, Blaschke T. Adherence to medication. N Engl J Med. 2005;353:487-497.
(7) Sokol MC, McGuigan KA, Verbrugge RR, Epstein RS. Impact of medication adherence on hospitalization risk and healthcare cost. Med Care. 2005;43(6):521-30.
(8) Gibson TB, Ozminkowski RJ, Goetzel RZ. The effects of prescription drug cost sharing: a review of the evidence. Am J Manag Care. 2005;11:730-740.
(9) Lexchin J, Grootendorst P. Effects of prescription drug user fees on drug and health services use and on health status in vulnerable populations: a systematic review of the evidence. Int J Health Serv. 2004;34:101-122.
(10) Goldman DP, Joyce GF, Escarce JJ et al. Pharmacy benefits and the use of drugs by the chronically ill. JAMA. 2004;291:2344-2350.
(11) CDC, "Chronic Disease Overview: Costs of Chronic Disease," available at, accessed October 20, 2006.
(12) American College of Physicians. "Costs and Quality Associated With Treating Medicare Patients With Multiple Chronic Diseases." Available at Accessed September 18, 2007. 07.
(13) Devol R and Bedroussian A. An Unhealthy America: The Economic Burden of Chronic Disease. Milken Institute. October 2007.

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GlaxoSmithKline (GSK) is one of the world's leading pharmaceutical and healthcare companies and is committed to improving the quality of human life by enabling people to do more, feel better and live longer. GSK has a comprehensive global programme of community partnerships focused on improving health and education. In the UK, GSK supports over 70 charitable organizations in health, science education, the arts and the environment.

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