DISTANCE Survey

The Diabetes Study of Northern California (DISTANCE) conducts epidemiological and health services research in diabetes among a large, multiethnic cohort of patients in a large integrated healthcare delivery system.

BACKGROUND AND AIMS

DISTANCE began in 2003 as a study of social disparities in diabetes-related health outcomes. Its original aims were to identify potentially modifiable factors that might explain pathways linking social factors, particularly educational attainment and ethnicity, to diabetes-related health outcomes. Today, DISTANCE includes four broad areas of study:

1. Social Disparities Research
2. Aging Research (The Diabetes & Aging Study)
3. Medication Adherence Research
4. Health Information Technology (HIT)

METHODS

Setting

All subjects are members of Kaiser Permanente Northern California (Kaiser), a large, integrated healthcare delivery system. Kaiser provides comprehensive medical services to over 3.2 million members in Northern California, more than 25% of the region's population; the membership closely approximates the general population of the region ethnically and socioeconomically except for the extreme tails of the income distribution. Care is provided by approximately 4,400 physicians at 17 hospitals and 152 medical offices.

Data Sources

Kaiser Permanente Electronic Medical Record

Since 2004, Kaiser has operated KP HealthConnect (KPHC), an integrated electronic medical record (EMR) system designed by the Epic Corporation to automate its patient files and make documentation of care more efficient and complete. KP HealthConnect replaced many of the core utilization and clinical documentation legacy applications, including ambulatory visit check-in, hospital-based utilization, and clinical documentation of diagnoses, orders for tests and procedures, and prescribed Inpatient medications. In addition to replacing many existing legacy functions, KPHC has significantly enhanced the scope and detail of available data.

Diabetes Registry at KPNC

As of January, 2011, the Registry had ~232,000 patients with clinically recognized diabetes. The Kaiser Permanente Northern California Diabetes Registry ("Registry") was first established in 1993 using standardized criteria to identify and prospectively follow members with diabetes, to measure prevalence and incidence of diabetes and its co-morbidities, to understand factors associated with disease progression and complications, and to evaluate health care processes and outcomes.
We conducted the first survey of the Registry in 1994-97 among all Registry members over 19 years of age. The primary goal of that survey was to capture individual-level information on the clinical characteristics of diabetes, age at diagnosis, ethnicity, education, health-related behaviors and diabetes family history. There were 77,726 respondents (83% response rate among eligible members) and that survey cohort has been the basis for numerous publications regarding the epidemiological and health services aspects of diabetes.

DISTANCE Survey

In 2005-2006, we conducted a second survey, the DISTANCE Survey, among an ethnically-stratified, random sample of diabetic members of known (Caucasian, African-American, Latino, Asian) and unknown ethnicity receiving care from Kaiser. The Survey assessed a wide range of behavioral, social and economic factors (ethnicity, educational attainment, health literacy, health behaviors, diabetes knowledge, perceptions, attitudes and psychosocial attributes) that may explain observed variations in the incidence of diabetes complications, including myocardial infarction, stroke, congestive heart failure, end-stage renal disease, lower-extremity amputation, proliferative retinopathy, acute metabolic events and death. Understanding factors which are predictive of poor health outcomes may facilitate the design of targeted interventions to reduce health disparities. We hypothesized that these factors may differ substantively in prevalence or effect size across ethnic groups or educational levels.

The DISTANCE Survey was completed by 20,188 patients (62% response rate among eligible members): 3,420 African Americans (16.9%), 2,312 Asian (11.4%), 4,602 Caucasians (22.8%), 2,404 Filipinos (11.9%), 3,717 Latinos (18.4%), 2,222 multi-racial (11.0%) and 1,511 other (7.5%). Respondents varied widely in terms of clinical and behavioral profiles, as well as education, income, wealth, occupation, nativity and neighborhood characteristics. However relatively few baseline variables differed between respondents and non-respondents. Moreover, analyses of response bias focusing on associations between race or education and poor glycemic control (A1C>7%) detected no significant differences (p=0.55 and 0.28 for survey response interaction with race and education, respectively). The complete survey is available online (DISTANCE Survey) and a published description of methods is available at Int J Epidemiol or PubMed Central.

INVESTIGATORS

DISTANCE is supported by the efforts of many investigators and collaborators (institutions for identification purposes only):

FUNDING

DISTANCE is or has been supported by the following grants:

PRIVACY

All information obtained, including responses to the DISTANCE Survey, are kept confidential, are maintained by the Division of Research and used for research purposes only. No information gathered will become part of anyone's medical record or shared with their doctor. Also, no individuals will ever be identified in published reports. We only report our findings for the whole group of survey participants. The DISTANCE Survey has been approved by the Kaiser Foundation Research Institute's Institutional Review Board (IRB), which oversees all research and protection of study participants. This board reviews study plans to ensure that researchers respect and protect the privacy and confidentiality of study participants.

CONTACT

For more information or to collaborate, please contact Howard H. Moffet, MPH.

We are not free to release participants' personal data under our promise to them regarding confidentiality. However, the DISTANCE is interested in collaborations with external researchers. DISTANCE investigators are particularly interested in comparing processes and outcomes in this insured population with uniform access to care to disparities observed in population-based samples, where quality and access to care vary widely by social strata. Requests for collaboration must be submitted to the director of the central coordinating center. Before collaborations can be initiated, proposals require review and approval by the Publications and Presentations (P&P) Committee. This committee was formed to: (i) Ensure accurate, uniform, timely and high quality reporting of DISTANCE findings; (ii) Preserve the scientific integrity of the study and (iii) Safeguard the rights and confidentiality of participants.

DISTANCE PUBLICATIONS

2008

Moffet HH, Adler N, Schillinger D, Ahmed AT, Laraia B, Selby JV, Neugebauer R, Liu
JY, Parker MM, Warton M, Karter AJ. Cohort Profile: The Diabetes Study of Northern
California (DISTANCE)--objectives and design of a survey follow-up study of social
health disparities in a managed care population. Int J Epidemiol. 2009 Feb;38(1):38-47.
Epub 2008 Mar 7. PubMed PMID: 18326513; PubMed Central PMCID: PMC2635421.
http://www.ncbi.nlm.nih.gov/pubmed/18326513

2009

Whitmer RA, Karter AJ, Yaffe K, Quesenberry CP Jr, Selby JV. Hypoglycemic episodes
and risk of dementia in older patients with type 2 diabetes mellitus. JAMA. 2009 Apr
15;301(15):1565-72. PubMed PMID: 19366776; PubMed Central PMCID: PMC2782622.
http://www.ncbi.nlm.nih.gov/pubmed/19366776

2010

Ahmed AT, Go AS, Warton EM, Parker MM, Karter AJ. Ethnic differences in anemia
among patients with diabetes mellitus: the Diabetes Study of Northern California
(DISTANCE). Am J Hematol. 2010 Jan;85(1):57-61. PubMed PMID: 20029942;
PubMed Central PMCID: PMC2851744.
http://www.ncbi.nlm.nih.gov/pubmed/20029942

Schenker Y, Karter AJ, Schillinger D, Warton EM, Adler NE, Moffet HH, Ahmed AT,
Fernandez A. The impact of limited English proficiency and physician language
concordance on reports of clinical interactions among patients with diabetes: the
DISTANCE study. Patient Educ Couns. 2010 Nov;81(2):222-8. Epub 2010 Mar 11.
PubMed PMID: 20223615; PubMed Central PMCID: PMC2907435.
http://www.ncbi.nlm.nih.gov/pubmed/20223615

Moffet HH, Schillinger D, Weintraub JA, Adler N, Liu JY, Selby JV, Karter AJ. Social
disparities in dental insurance and annual dental visits among medically insured
patients with diabetes: the Diabetes Study of Northern California (DISTANCE) Survey.
Prev Chronic Dis. 2010 May;7(3):A57. Epub 2010 May 15. PubMed PMID: 20394696;
PubMed Central PMCID: PMC2879989.
http://www.ncbi.nlm.nih.gov/pubmed/20394696

Sarkar U, Karter AJ, Liu JY, Moffet HH, Adler NE, Schillinger D. Hypoglycemia is more
common among type 2 diabetes patients with limited health literacy: the Diabetes Study
of Northern California (DISTANCE). J Gen Intern Med. 2010 Sep;25(9):962-8. Epub
2010 May 18. Erratum in: J Gen Intern Med. 2010 Nov;25(11):1258. PubMed PMID:
20480249; PubMed Central PMCID: PMC2917655.
http://www.ncbi.nlm.nih.gov/pubmed/20480249

Sarkar U, Karter AJ, Liu JY, Adler NE, Nguyen R, Lopez A, Schillinger D. The literacy
divide: health literacy and the use of an internet-based patient portal in an integrated
health system-results from the diabetes study of northern California (DISTANCE). J
Health Commun. 2010;15 Suppl 2:183-96. PubMed PMID: 20845203; PubMed Central
PMCID: PMC3014858
http://www.ncbi.nlm.nih.gov/pubmed/20845203

Huang ES, Karter AJ, Danielson KK, Warton EM, Ahmed AT. The association between
the number of prescription medications and incident falls in a multi-ethnic population of
adult type-2 diabetes patients: the diabetes and aging study. J Gen Intern Med. 2010
Feb;25(2):141-6. Epub 2009 Dec 5. PubMed PMID: 19967465; PubMed Central
PMCID: PMC2837501
http://www.ncbi.nlm.nih.gov/pubmed/19967465

Fernandez A, Schillinger D, Warton EM, Adler N, Moffet HH, Schenker Y, Salgado MV,
Ahmed A, Karter AJ. Language barriers, physician-patient language concordance, and
glycemic control among insured Latinos with diabetes: the Diabetes Study of Northern
California (DISTANCE). J Gen Intern Med. 2011 Feb;26(2):170-6. Epub 2010 Sep 29.
PubMed PMID: 20878497; PubMed Central PMCID: PMC3019330.
http://www.ncbi.nlm.nih.gov/pubmed/20878497

Kanaya A, Karter AJ. Type 2 Diabetes in Asian American and Pacific Islander
populations: A view from California. California Diabetes Program Issues Brief. May
2010.

2011

Lyles CR, Karter AJ, Young BA, Spigner C, Grembowski D, Schillinger D, Adler N.
Provider factors and patient-reported healthcare discrimination in the Diabetes Study of
California (DISTANCE). Patient Educ Couns. 2011 May 21. [Epub ahead of print]
PubMed PMID: 21605956.
http://www.ncbi.nlm.nih.gov/pubmed/21605956

Lyles CR, Karter AJ, Young BA, Spigner C, Grembowski D, Schillinger D, Adler NE.
Correlates of Patient-Reported Racial/Ethnic Health Care Discrimination in the Diabetes
Study of Northern California (DISTANCE). J Health Care Poor Underserved.
2011;22(1):211-25. PubMed PMID: 21317516; PubMed Central PMCID: PMC3075840.
http://www.ncbi.nlm.nih.gov/pubmed/21317516

Kanaya, Adler, Moffet, Schillinger, Adams, Ahmed, Karter. Heterogeneity of Diabetes
Outcomes among East Asians, South Asians and Pacific Islanders in the U.S.: The
Diabetes Study of Northern California (DISTANCE). Diabetes Care. 2011
Apr;34(4):930-7. Epub 2011 Feb 24. PubMed PMID: 21350114; PubMed Central
PMCID: PMC3064053.
http://www.ncbi.nlm.nih.gov/pubmed/21350114

Sarkar U, Karter AJ, Liu JY, Adler NE, Nguyen R, López A, Schillinger D. Social
disparities in internet patient portal use in diabetes: evidence that the digital divide
extends beyond access. J Am Med Inform Assoc. 2011 May 1;18(3):318-21. Epub 2011
Jan 24. PubMed PMID: 21262921; PubMed Central PMCID: PMC3078675.
http://www.ncbi.nlm.nih.gov/pubmed/21262921

Huang ES, Liu JY, Moffet HH, John PM, Karter AJ. Glycemic Control, Complications,
and Death in Older Diabetic Patients. Diabetes Care 2011 Jun;34(6):1329-36. Epub
2011 Apr 19. PubMed PMID: 21505211.
http://www.ncbi.nlm.nih.gov/pubmed/21505211

Callaghan BC, Feldman E, Liu J, Kerber K, Pop-Busui R, Moffet H, Karter AJ.
Triglycerides and amputation risk in patients with diabetes: ten-year follow-up in the
DISTANCE study. Diabetes Care. 2011 Mar;34(3):635-40. Epub 2011 Feb 1. PubMed
PMID: 21285390; PubMed Central PMCID: PMC3041196.
http://www.ncbi.nlm.nih.gov/pubmed/21285390

Laiteerapong N, Karter AJ, Liu JY, Moffet HH, Sudore R, Schillinger D, John PM, Huang
ES. Correlates of quality of life in older adults with diabetes: The Diabetes & Aging
Study. Diabetes Care. 2011 Jun 2.. [Epub ahead of print]
http://www.ncbi.nlm.nih.gov/pubmed/21636795

Moffet HH, Parker MM, Sarkar U, Schillinger D, Fernandez A, Adler NE, Adams AS,
Karter AJ. Adherence to laboratory test requests by patients with diabetes: the Diabetes
Study of Northern California (DISTANCE). Am J Manag Care. 2011 May;17(5):339-44.
PubMed PMID: 21718081.
http://www.ncbi.nlm.nih.gov/pubmed/21718081

Moskowitz D, Lyles CR, Karter AJ, Adler N, Moffet HH, Schillinger D. Patient reported
interpersonal processes of care and perceived social position: The Diabetes Study of
Northern California (DISTANCE). Patient Educ Couns. 2011 Aug 18. [Epub ahead of
print] PubMed PMID: 21855266.
http://www.ncbi.nlm.nih.gov/pubmed/21855266

Parker MM, Moffet HH, Schillinger D, Adler N, Fernandez A, Ciechanowski P, Karter AJ.
Ethnic Differences in Appointment-Keeping and Implications for the Patient-Centered
Medical Home-Findings from the Diabetes Study of Northern California (DISTANCE).
Health Serv Res. 2011 Oct 27. doi: 10.1111/j.1475-6773.2011.01337.x.
[Epub ahead of print] PubMed PMID: 22091785.
http://www.ncbi.nlm.nih.gov/pubmed/22091785

Katon W, Lyles CR, Parker MM, Karter AJ, Huang ES, Whitmer RA.
Association of Depression With Increased Risk of Dementia in Patients With Type 2 Diabetes:
The Diabetes and Aging Study. Arch Gen Psychiatry. 2011 Dec 5.
[Epub ahead of print] PubMed PMID: 22147809.
http://www.ncbi.nlm.nih.gov/pubmed/22147809

Lyles CR, Karter AJ, Young BA, Spigner C, Grembowski D, Schillinger D, Adler N.
Patient-Reported Racial/Ethnic Healthcare Provider Discrimination and Medication
Intensification in the Diabetes Study of Northern California (DISTANCE). J Gen Intern
Med. 2011 Oct;26(10):1138-44. Epub 2011 May 6. PubMed PMID: 21547610
http://www.ncbi.nlm.nih.gov/pubmed/21547610

Choi AI, Karter AJ, Liu JY, Young B, Go AS, Schillinger D. Ethnic Differences in the
Devleopment of Alburminuria: The Diabetes Study of Northern California (DISTANCE).
American Journal of Managed Care. 2011;17(11):737-745. PMID:22084893
http://www.ncbi.nlm.nih.gov/pubmed/22084893

2012

Ratanawongsa N, Crosson JC, Schillinger D, Karter AJ, Saha CK, Marrero DG.
Getting Under the Skin of Clinical Inertia in Insulin Initiation: The Translating Research Into
Action for Diabetes (TRIAD) Insulin Starts Project. Diabetes Educ. 2012 Jan 5.
[Epub ahead of print] PubMed PMID: 22222513. 
http://www.ncbi.nlm.nih.gov/pubmed/22222513

Laraia B, Karter AJ, Warton M, Schillinger D, Moffet HH, Adler N.
Place matters: Neighborhood deprivation and cardiometabolic risk factors among
adults with diabetes. Social Science & Medicine. Jan 26, 2012 [ePub ahead of print] 
http://www.ncbi.nlm.nih.gov/pubmed/22373821