Regional,Geographic,and Ethnic Differences in Medication Adherence among Adults with Type 2 Diabetes

Abstract

Spanish

French

BACKGROUND:

Medication adherence, a critical component of glycemic control for patients with type 2 diabetes, differs by race/ethnicity. However, few studies have examined regional and rural/urban differences in medication adherence and whether racial/ethnic differences persist after controlling for these differences.

OBJECTIVE:

To examine regional, rural/urban, and racial/ethnic differences in medication adherence in a national sample of veterans with type 2 diabetes.

METHODS:

We performed a cohort study of a national sample of veterans with diabetes (N = 690,968) receiving prescriptions for insulin or oral hypoglycemic agents in 2002. Patients were followed until death, loss to follow-up, or through December 2006. We calculated the annual medication possession ratio (MPR) for each veteran across 4 groups of medication users: individuals using (1) insulin only, (2) oral hypoglycemic agents only, (3) insulin combined with hypoglycemic agents, and (4) insulin or oral hypoglycemic agents (primary analysis).

RESULTS:

In longitudinal models for the primary analysis, adjusting for relevant covariates and time trends, MPR was significantly lower among non-Hispanic blacks (NHBs), Hispanics, and individuals with other/missing/unknown race/ethnicity (6.07%, 1.76%, and 2.83% lower, respectively) relative to non-Hispanic whites (NHWs). MPR was also 2.0% higher in rural versus urban veterans and 1.28% higher in the mid-Atlantic, 2.04% higher in the Midwest, and 0.76% lower in the West, relative to the South. There was a significant race/ethnicity and urban/rural interaction. In NHWs and NHBs, MPR was 1.91 % and 2.00% higher, respectively, in rural versus urban veterans; in contrast, in Hispanics, MPR was 1.0% lower in rural veterans relative to urban veterans.

CONCLUSIONS:

In a national longitudinal cohort of veterans with type 2 diabetes, we found significant regional, rural/urban, and racial/ethnic differences in MPR. Rural/urban residence modified the effect of race/ethnicity on MPR. Recognition of these differences can enable clinicians to better allocate resources and target quality improvement programs.

Keywords

cohort diabetes mellitus health disparities medication adherence

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References

Centers for Disease Control and Prevention. National diabetes fact sheet: General information and estimates on diabetes in the United States, 2007. Atlanta: US Department of Health and Human Services, 2007.

Dall

T M

Zhang

Chen

Y J

Quick

W W

Yang

W G

Fogli

The economic burden of diabetes. Health Aff (Millwood) 2010; 29: 297–303.

Economic costs of diabetes in the US in 2007. Diabetes Care 2007; 31: 596–615.

The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group. N Engl J Med 1993; 329: 977–86.

Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes (UKPDS 34). UK Prospective Diabetes Study (UKPDS) Group. Lancet 1998; 352: 854–65. DOI S0140673698070378.

Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). UK Prospective Diabetes Study (UKPDS) Group. Lancet 1998; 352: 837–53. DOI S0140673698070196.

Stratton

I M

Adler

A I

Neil

H A

. Association of glycaemia with macrovascular and microvascular complications of type 2 diabetes (UKPDS 35): Prospective observational study. BMJ 2000; 321: 405–12.

Turner

R C

Cull

C A

Frighi

Holman

R R

. Glycemic control with diet, sulfonylurea, metformin, or insulin in patients with type 2 diabetes mellitus: Progressive requirement for multiple therapies (UKPDS 49). UK Prospective Diabetes Study (UKPDS) Group. JAMA 1999; 281: 2005–12. DOI joc72221.

Saaddine

J B

Cadwell

Gregg

E W

. Improvements in diabetes processes of care and intermediate outcomes: United States, 1988–2002. Ann Intern Med 2006; 144: 465–74. DOI 144/7/465.

10.

Saaddine

J B

Engelgau

M M

Beckles

G L

Gregg

E W

Thompson

T J

Narayan

K M

. A diabetes report card for the United States: Quality of care in the 1990s. Ann Intern Med 2002; 136: 565–74. DOI 200204160-00005.

11.

Schectman

J M

Nadkarni

M M

Voss

J D

. The association between diabetes metabolic control and drug adherence in an indigent population. Diabetes Care 2002; 25: 1015–21.

12.

Sokol

M C

McGuigan

K A

Verbrugge

R R

Epstein

R S

. Impact of medication adherence on hospitalization risk and healthcare cost. Med Care 2005; 43: 521–30. DOI 00005650-200506000-00002.

13.

Menzin

Langley-Hawthorne

Friedman

Boulanger

Cavanaugh

Potential short-term economic benefits of improved glycemic control: A managed care perspective. Diabetes Care 2001; 24: 51–5.

14.

Balkrishnan

Rajagopalan

Camacho

F T

Huston

S A

Murray

F T

Anderson

R T

. Predictors of medication adherence and associated health care costs in an older population with type 2 diabetes mellitus: A longitudinal cohort study. Clinical Ther 2003; 25: 2958–71. DOI S0149291803803478.

15.

Kim

Agostini

J V

Justice

A C

. Refill adherence to oral hypoglycemic agents and glycemic control in veterans. Ann Pharmacother 2010; 44: 800–8. DOI 10.1345/aph.1M570.

16.

Cramer

J A

. A systematic review of adherence with medications for diabetes. Diabetes Care 2004; 27: 1218–24.

17.

Odegard

P S

Capoccia

Medication taking and diabetes: A systematic review of the literature. Diabetes Educator 2007; 33: 1014–29; discussion 30–1. DOI 10.1177/0145721707308407.

18.

Harris

M I

Eastman

R C

Cowie

C C

Flegal

K M

Eberhardt

M S

. Racial and ethnic differences in glycemic control of adults with type 2 diabetes. Diabetes Care 1999; 22: 403–8.

19.

Eberhardt

M S

Lackland

D T

Wheeler

F C

German

R R

Teutsch

S M

. Is race related to glycemic control? An assessment of glycosylated hemoglobin in two South Carolina communities. J Clin Epidemiol 1994; 47: 1181–9. DOI 0895-4356(94)90105-8.

20.

Gary

T L

McGuire

McCauley

Brancati

F L

. Racial comparisons of health care and glycemic control for African American and white diabetic adults in an urban managed care organization. Dis Manag 2004; 7: 25–34. DOI 10.1089/109350704322918970.

21.

Shenolikar

R A

Balkrishnan

Oral antidiabetes medication adherence and health care utilization among Medicaid-enrolled type 2 diabetic patients beginning monotherapy. Diabetes Care 2008; 31: e5.

22.

Cramer

J A

Pugh

M J

. The influence of insulin use on glycemic control: How well do adults follow prescriptions for insulin? Diabetes Care 2005; 28: 78–83. DOI 28/1/78.

23.

Fisher

Goodman

Skinner

Bronner

Health care spending, quality, and outcomes: More isn't always better. The Dartmouth Atlas Project 2009. Lebanon, NH: The Trustees of Dartmouth College, 2009.

24.

Wennberg

J E

. The quality of medical care in the United States: A report on the Medicare program. Hanover, NH: The Center for the Evaluative Clinical Sciences Dartmouth Medical School, 1999.

25.

Subramanian

Weinberger

Eckert

G J

L'Italien

G J

Lapuerta

Tierney

Geographic variation in health care utilization and outcomes in veterans with acute myocardial infarction. J Gen Intern Med 2002; 17: 604–11. DOI jgi11048.

26.

Tseng

C L

Helmer

Rajan

. Evaluation of regional variation in total, major, and minor amputation rates in a national health-care system. Int J Qual Health Care 2007; 19: 368–76. DOI 10.1093/intqhc/mzm044.

27.

Williams

L S

Eckert

G J

L'Italien

G J

Lapuerta

Weinberger

Regional variation in health care utilization and outcomes in ischemic stroke. J Stroke Cerebrovasc Dis 2003; 12: 259–65. DOI 10.1016/j.jstrokecerebrovasdis.2003.09.008.

28.

Larson

S L

Fleishman

J A

. Rural–urban differences in usual source of care and ambulatory service use: Analyses of national data using Urban Influence Codes. Med Care 2003; 41: III65–74. DOI 10.1097/01.MLR.0000076053.28108.F2.

29.

Rosenthal

T C

Fox

Access to health care for the rural elderly. JAMA 2000; 284: 2034–6.

30.

Van Dis

MSJAMA. Where we live: Health care in rural vs urban America. JAMA 2002; 287: 108. DOI jms0102-2.

31.

Weeks

W B

Kazis

L E

Shen

. Differences in health-related quality of life in rural and urban veterans. Am J Public Health 2004; 94: 1762–7. DOI 94/10/1762.

32.

Weeks

W B

Lee

R E

Wallace

A E

West

A N

Bagian

J P

. Do older rural and urban veterans experience different rates of unplanned readmission to VA and non-VA hospitals? J Rural Health 2009; 25: 62–9. DOI 10.1111/j.1748-0361.2009.00200.x.

33.

Morgan

R O

Petersen

L A

Hasche

J C

. VHA pharmacy use in veterans with Medicare drug coverage. Am J Manag Care 2009; 15: e1–8.

34.

Shen

Hendricks

Zhang

Kazis

L E

. VHA enrollees' health care coverage and use of care. Med Care Res Rev 2003; 60: 253–67.

35.

Zhu

S C

Gardner

J A

Hendricks

How many enrollees come to VA just for pharmacy?

Health Care Financing and Economics Data Brief #2004–10. www.hcfe.research.va.gov (accessed 2010 Oct 8).

36.

Miller

D R

Safford

M M

Pogach

L M

. Who has diabetes? Best estimates of diabetes prevalence in the Department of Veterans Affairs based on computerized patient data. Diabetes Care 2004; 27 (suppl 2): B10–21.

37.

Karve

Cleves

M A

Helm

Hudson

T J

West

D S

Martin

B C

. An empirical basis for standardizing adherence measures derived from administrative claims data among diabetic patients. Med Care 2008; 46: 1125–33. DOI 10.1097/MLR.0b013e31817924d2.

38.

West

A N

Lee

R E

Shambaugh-Miller

M D

. Defining “rural” for veterans' health care planning. J Rural Health 2010; 26: 301–9. DOI 10.1111/j.1748-0361.2010.00298.x.

39.

Department of Veterans Affairs Field Research Advisory Committee. (2004). Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Field Research Advisory Committee Operating Procedures. Washington, DC: 2004.

40.

Diggle

Liang

Zeger

Analysis of longitudinal data, vol 25. 2nd ed. New York: Oxford University Press, 2002.

41.

Donnelly

L A

Morris

A D

Evans

J M

. Adherence to insulin and its association with glycaemic control in patients with type 2 diabetes. QJM 2007; 100: 345–50. DOI 10.1093/qjmed/hcm031.

42.

P M

Rumsfeld

J S

Masoudi

F A

. Effect of medication nonadherence on hospitalization and mortality among patients with diabetes mellitus. Arch Intern Med 2006; 166: 1836–41. DOI 10.1001/archinte.166.17.1836.

43.

Zhang

Lave

J R

Donohue

J M

Fischer

M A

Chernew

M E

Newhouse

J P

. The impact of Medicare Part D on medication adherence among older adults enrolled in Medicare-Advantage products. Med Care; 48: 409–17. DOI 10.1097/MLR.0b013e3181d68978.

44.

Donnan

P T

MacDonald

T M

Morris

A D

. Adherence to prescribed oral hypoglycaemic medication in a population of patients with type 2 diabetes: A retrospective cohort study. Diabet Med 2002; 19: 279–84. DOI 10.1046/j.1464-5491.2002.00689.x.

45.

Doro

Benko

Kosik

Matuz

Toth

Soos

Utilization of oral antihyperglycemic drugs over a 7-year period (1998–2004) in a Hungarian population and adherence to drug therapy. Eur J Clin Pharmacol 2005; 61: 893–7. DOI 10.1007/s00228-005-0031-9.

46.

Hertz

R P

Unger

A N

Lustik

M B

. Adherence with pharmacotherapy for type 2 diabetes: A retrospective cohort study of adults with employer-sponsored health insurance. Clin Ther 2005; 27: 1064–73. DOI 10.1016/j.clinthera.2005.07.009.

47.

Kalsekar

I D

Madhavan

S S

Amonkar

M M

. Depression in patients with type 2 diabetes: Impact on adherence to oral hypoglycemic agents. Ann Pharmacother 2006; 40: 605–11. DOI 10.1345/aph.1G606.

48.

Rhee

M K

Slocum

Ziemer

D C

. Patient adherence improves glycemic control. Diabetes Educ 2005; 31: 240–50. DOI 10.1177/0145721705274927.

49.

Sclar

D A

Robison

L M

Skaer

T L

Dickson

W M

Kozma

C M

Reeder

C E

. Sulfonylurea pharmacotherapy regimen adherence in a Medicaid population: Influence of age, gender, and race. Diabetes Educ 1999; 25: 531–2, 535, 537–8.

50.

Rosen

M I

Beauvais

J E

Rigsby

M O

Salahi

J T

Ryan

C E

Cramer

J A

. Neuropsychological correlates of suboptimal adherence to metformin. J Behav Med 2003; 26: 349–60.

51.

Gerber

B S

Cho

Y I

Arozullah

A M

Lee

S Y

. Racial differences in medication adherence: A cross-sectional study of medicare enrollees. Am J Geriatr Pharmacother 2010; 8: 136–45. DOI 10.1016/j.amjopharm.2010.03.002.

52.

Venturini

Nichol

M B

Sung

J C

Bailey

K L

Cody

McCombs

J S

. Compliance with sulfonylureas in a health maintenance organization: A pharmacy record–based study. Ann Pharmacother 1999; 33: 281–8. DOI 10.1345/aph.18198.