Diabetes-Specific Preventive-Care Practices Among Adults in a Managed-Care Population -- Colorado, Behavioral Risk Factor Surveillance System, 1995

The prevalence of diagnosed diabetes in the United States is 3%; however, diabetes accounts for approximately 15% of total U.S. health-care expenditures (1). Preventive-care practices (e.g., glycemic control and regular foot and ophthalmic examinations) can reduce the occurrence and progression of diabetic complications (2-4). Although managed-care organizations (MCOs) have assessed the use of such practices through chart reviews (5), telephone surveys of MCO patients with diabetes are a less expensive method for collecting accurate data (6). The ongoing, state-based Behavioral Risk Factor Surveillance System (BRFSS) telephone survey can be used to assess levels of care provided by MCOs and self-care practices among persons with diabetes in MCO populations (6). In 1995, a Colorado-based MCO collaborated with the Colorado Diabetes Control Program (CDCP) to use the state-based BRFSS to assess care practices among MCO enrollees. This report presents findings from the CDCP analysis of data on MCO enrollees aged greater than or equal to 30 years who had diabetes; the findings indicate that, although approximately three fourths of enrollees reported most preventive-care practices, two thirds had never heard the term hemoglobin "A-one-C," one fourth had not had their feet examined during the preceding year, and nearly one fifth did not receive an annual dilated-eye examination.

A 12% stratified random sample was selected of 500 MCO enrollees aged greater than or equal to 30 years who had been enrolled for at least 3 years and were receiving care in any one of five main medical facilities operated by the MCO (total eligible: n=4240). Enrollees who had obtained insulin or oral hypoglycemic agents from the MCO pharmacy were considered to have diabetes. The type of diabetes was derived from self-reported data: enrollees were classified as having 1) type 1 diabetes if they were aged less than 30 years when diabetes was diagnosed and were using insulin currently or 2) type 2 diabetes if they were aged greater than or equal to 30 years when diabetes was diagnosed or were not using insulin currently. Self-monitoring of blood glucose (SMBG) and visiting a health-care provider (HCP) for diabetes care at least once during the year preceding the interview were used as indicators of self-care. Awareness of the term hemoglobin "A one C" (HbA1c) * was used as an indicator of having received diabetes education. Use of HbA1c to monitor long-term glycemic control, foot examinations, and dilated-eye examinations were used as indicators of preventive care received from HCP during the previous year. Level of care was estimated as the percentage of respondents that reported each preventive-care practice. Chi-square tests were used to determine whether insulin use, duration of diabetes, and selected sociodemographic characteristics were associated with level of self-care or HCP-preventive care. Analyses were conducted using Statistical Analysis System (SAS) (7).

Of the 469 (93.8%) persons who participated in the survey, 86.1% were aged greater than or equal to 45 years, 85.3% were white, 53.7% were educated beyond high school, and 54.1% reported having had diabetes for greater than or equal to 10 years (Table_1). A total of 349 (74.4%) respondents had type 2 diabetes, 66 (14.1%) had type 1, and 54 (11.5%) had diabetes that could not be categorized. Among persons with type 2 diabetes, 253 (72.5%) reported currently using insulin.

Overall, 90.4% of respondents reported that they performed SMBG (Table_2). Reported SMBG was higher among those who used insulin (among persons with type 1 diabetes, 98.5%, and among persons with type 2, 93.7%) than among nonusers (78.1%) (difference=16%, 95% confidence interval {CI}=7%-27%), increased directly with duration of diabetes (p less than 0.01) and level of education (p less than 0.01), and decreased with increasing age (p less than 0.01). Overall, 33.1% of respondents recalled ever having heard the term HbA1c. Reported awareness of HbA1c was highest among those who used insulin (among persons with type 1 diabetes, 69.7%, and among persons with type 2, 30.0%) than among nonusers (22.9%) (difference=13%, 95% CI=3%-23%) and was two times higher among persons with type 1 diabetes than among persons with type 2 (difference=40%, 95% CI=28%-52%), five times higher among college graduates than among persons who had not completed high school (p less than 0.01), and four times higher among persons aged greater than or equal to 65 years than among those aged 30-44 years (p less than 0.01). Of all respondents, 83.4% reported at least one visit for diabetes care during the year preceding the interview. Reporting at least one visit during the preceding year was higher among those who used insulin (among persons with type 1 diabetes, 89.4%, and among persons with type 2, 84.6%) than among nonusers (74.0%) (difference=12%, 95% CI=2%-14%) and decreased significantly with increasing age (p less than 0.01).

A total of 28.8% of respondents reported that their HbA1c had been checked by an HCP at least once during the preceding year, and 76.1% reported that an HCP had examined their feet at least once during the same period (Table_2). Reported foot examination was higher among those who used insulin (among persons with type 1 diabetes, 86.4%, and among persons with type 2, 77.9%) than among nonusers (64.6%) (difference=24%, 95% CI=11%-35%) and among whites (78.0%) than among races other than white (65.2%) (difference=13%, 95% CI=1%-25%), and decreased with increasing age (p less than 0.01). Finally, 84.0% of respondents reported having had a dilated-eye examination during the year preceding the interview; the percentage increased with increasing duration of diabetes (p less than 0.01).

Reported by: N Calonge, MD, D Berman, MD, Kaiser Permanente, Denver; T Dunn, MD, C Fry, Colorado Foundation for Medical Care, Denver; S Michael, MS, M Leff, MSPH, S Woodruff, MSPH, Colorado Dept of Public Health and Environment. Epidemiology and Statistics Br, Div of Diabetes Translation, National Center for Chronic Disease Prevention and Health Promotion, CDC.

Editorial Note

Editorial Note: Preventive-care practices are essential to efforts to reduce the burden of diabetes. Routine use of SMBG or HCP-monitoring of HbA1C can improve glycemic control and reduce the occurrence of complications of diabetes (2). In addition, foot-care programs can reduce the risk for foot complications by 50%-60% (3), and early detection and treatment of retinopathy can reduce the risk for severe vision loss by approximately 60% in persons with macular edema and approximately 90% in persons with proliferative retinopathy (4). Furthermore, some of these medical interventions are cost-effective (4,8).

The findings in this report indicate that, although approximately three fourths of enrollees reported most preventive-care practices, two thirds had never heard the term hemoglobin "A-one-C," one fourth had not had their feet examined during the preceding year, and nearly one fifth did not receive an annual dilated-eye examination. Findings from previous studies indicate that HCPs check HbA1c infrequently (5). However, among persons with diabetes who received care from the Colorado MCO, a substantial proportion (87.0%) of those who were aware of HbA1c (33.1%) also reported the test was performed at least once during the preceding year, and chart reviews indicated that at least one HbA1c test had been recorded for approximately 90% of persons in the study (N. Calonge, Kaiser Permanente, personal communication, 1996). In Colorado, one reason for the reported low level of HbA1c checks by HCPs (28.8%) was the respondents' low level of familiarity with the term (33.1%). Therefore, until the general public is more familiar with the name of the test, medical records and laboratory data may provide more accurate information about use of the HbA1c test.

The findings in this report are subject to at least two other limitations. First, the findings are not generalizable to MCO enrollees with diabetes who used nonpharmacologic therapy, obtained diabetes medication from pharmacies outside the MCO, or who were enrolled for less than 3 years. Overall, approximately 10% of preventive services received by MCO enrollees were performed outside the MCO (N. Calonge, Kaiser Permanente, personal communication, 1996). Thus, for some preventive-care indicators, telephone surveys may provide more comprehensive information than chart reviews regarding levels of preventive care in an MCO population. Second, self-reported data may be subject to recall bias. The accuracy of these data requires further assessment through comparison with data from medical records or other sources.

In the United States, the number of persons with diabetes who receive medical care from MCOs is increasing (9). The findings in this report regarding diabetes-specific self-care and HCP preventive-care practices in an MCO population illustrate the usefulness of the BRFSS to assess diabetes care and to monitor care practices (10), particularly in MCO populations. In addition, MCOs can use the BRFSS to monitor the quality of diabetes care to ensure a level of care that can reduce the effects associated with preventable acute and chronic complications and to foster collaboration between MCOs and state health departments to reduce the impact of diabetes. In Colorado, these findings are being used to target interventions to improve diabetes care and reduce complications among enrollees with diabetes in the MCO population.

References

1. Harris MI. Summary. In: Harris MI, Cowie CC, Stern MP, Boyko EJ, Reiber GE, Bennett PH, eds. Diabetes in America. Washington, DC: US Department of Health and Human Services, Public Health Service, National Institutes of Health, 1995; DHHS publication no. (NIH)95-1468.

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

3. Litzelman DK, Slemenda CW, Langefeld CD, et al. Reduction of lower extremity clinical abnormalities in patients with non-insulin-dependent diabetes mellitus: a randomized controlled trial. Ann Intern Med 1993;119:36-41.

4. Ferris FL III. How effective are treatments for diabetic retinopathy? JAMA 1993;269:1290-1.

5. Peters AL, Legorreta AP, Ossorio RC, Davidson MB. Quality of outpatient care provided to diabetic patients: a health maintenance organization experience. Diabetes Care 1996;19:601-6.

6. CDC. Using chronic disease data: a handbook for public health practitioners. Atlanta, Georgia: US Department of Health and Human Services, Public Health Service, 1992.

7. SAS Institute, Inc. Statistical Analysis System (SAS), version 6.10 for Windows. Cary, North Carolina: SAS Institute, Inc, 1994.

8. The Diabetes Control and Complications Trial Research Group. Lifetime benefits and costs of intensive therapy as practiced in the Diabetes Control and Complications Trial. JAMA 1996; 276:1409-15.

9. Quickel KE Jr. Diabetes in a managed care system. Ann Intern Med 1996;124(part 2):160-3.

10. CDC. Preventive-care knowledge and practices among persons with diabetes mellitus -- North Carolina, Behavioral Risk Factor Surveillance System, 1994-1995. MMWR 1997;46:1023-7.

* HbA1c is a glycosylated hemoglobin used to monitor long-term glycemic control because it reflects average blood glucose levels during the preceding 6-8 weeks.

TABLE 1. Percentage distribution of selected characteristics among
managed-care organization enrollees aged >=30 years who had diabetes
-- Colorado, 1995
=======================================================================
Characteristic                 Sample size       % *       (95% CI+)
-----------------------------------------------------------------------
Age group (yrs)
 30-44                              62         13.2%   ( 4.8%-21.6%)
 45-64                             197         42.0%   (35.1%-48.9%)
  >=65                             207         44.1%   (37.3%-50.9%)
Unknown                              3          0.6%              --
Sex
 Men                               236         50.3%   (43.9%-56.7%)
 Women                             229         48.8%   (42.3%-55.3%)
 Unknown                             4          0.9%              --
Race&
 White                             400         85.3%   (81.8%-88.8%)
 Other                              69         14.7%   ( 6.3%-23.1%)
Education level
 Less than high school              79         16.8%   ( 8.6%-25.0%)
diploma
 High school graduate              137         29.2%   (21.6%-36.8%)
 Some college                      131         27.9%   (20.2%-35.6%)
 College graduate                  121         25.8%   (18.0%-33.6%)
 Unknown                             1          0.2%              --
Type of diabetes
 Type 1                             66         14.1%   ( 5.7%-22.5%)
 Type 2
  Insulin use                      253         53.9%   (47.8%-60.0%)
  No insulin use                    96         20.5%   (12.4%-28.6%)
 Unknown                            54         11.5%   ( 3.0%-20.0%)
Duration of diabetes (yrs)
  <=9 162 34.5% (27.2%-41.8%) 10-19 146 31.1% (23.6%-38.6%)>=20                             108         23.0%   (15.1%-30.9%)
Unknown                             53         11.3%   ( 2.8%-19.8%)
Total                              469        100.0%
-----------------------------------------------------------------------
* Percentage may not total 100% because of rounding.
+ Confidence interval.
& Number for racial/ethnic groups other than white were too small for
  meaningful analysis.
=======================================================================

TABLE 2. Percentage of managed-care organization enrollees aged >=30 years who had diabetes and who reported diabetes-specific self-care practices and preventive-care practices of health-care providers, by selected characteristics -- Colorado, 1995
========================================================================================================================================================================================================================================================
                                                                               Self-care pratctices     Preventive-care practices
                                           -------------------------------------------------------------------------------------------------------------                      --------------------------------------------------------------------------
             Examination
                                            Self-monitoring of blood-                    Awareness of                          At least one visit to a                                                    ----------------------------------------------
                                                   glucose                                  HbA1c+                             health-care provider                               HbA1c checked                  Dilated-eye               Foot
                                            -------------------------                 ---------------------                   --------------------------                      ----------------------      ---------------------   ----------------------
Characteristic                                     %        (95% CI&)                    %        (95% CI)                          %         (95% CI)                           %        (95% CI)             %        (95% CI)      %        (95% CI)
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Type of diabetes
 Type 1                                         98.5   (95.6%-101.4%)                 69.7   (58.6%-80.8%)                       89.4   (82.0%- 96.8%)                        65.2   (53.7%-76.7%)          87.9   (80.0%-95.8%)   86.4   (78.1%-94.7%)
 Type 2
   Insulin use                                  93.7   (90.7%- 96.7%)                 30.0   (24.4%-35.6%)                       84.6   (80.2%- 89.0%)                        25.7   (20.3%-31.1%)          84.6   (80.2%-89.0%)   77.9   (72.8%-83.0%)
   No insulin use                               78.1   (69.8%- 86.4%)                 22.9   (14.5%-31.3%)                       74.0   (65.2%- 82.0%)                        18.8   (11.0%-26.6%)          77.1   (68.7%-84.1%)   64.6   (59.7%-69.5%)
Duration of diabetes
(yrs)
   <=9                                          85.8   (80.4%- 91.5%)                 30.9   (23.8%-38.0%)                       81.5   (75.5%- 87.5%)                        27.2   (20.3%-34.1%)          75.3   (68.7%-81.9%)   72.8   (65.9%-79.7%)
 10-19                                          93.2   (89.1%- 97.3%)                 34.9   (27.2%-42.6%)                       86.3   (80.7%- 91.9%)                        29.5   (22.1%-36.9%)          88.4   (83.2%-93.6%)   76.0   (69.1%-82.9%)
  >=20                                          95.4   (91.4%- 99.4%)                 39.8   (30.6%-49.0%)                       80.6   (73.1%- 88.1%)                        36.1   (27.0%-45.2%)          89.8   (84.1%-95.5%)   80.6   (73.1%-88.1%)
Age group (yrs)
 30-44                                          96.8   (92.4%-101.1%)                 69.4   (57.9%-80.9%)                       96.8   (92.4%-101.2%)                        64.5   (52.6%-76.4%)          77.4   (72.1%-82.7%)   87.1   (78.8%-95.4%)
 45-64                                          94.9   (91.8%- 98.0%)                 39.1   (32.3%-45.9%)                       88.8   (84.4%- 93.2%)                        37.1   (30.4%-43.8%)          87.3   (82.7%-91.9%)   81.2   (75.4%-86.7%)
  >=65                                          84.5   (79.6%- 89.4%)                 16.9   (11.8%-22.0%)                       73.9   (67.9%- 79.9%)                        10.6   ( 6.4%-14.8%)          83.6   (78.6%-88.6%)   68.1   (61.8%-74.4%)
Sex
 Men                                            91.5   (87.9%- 95.1%)                 32.6   (26.6%-38.6%)                       84.3   (79.7%- 88.9%)                        28.4   (22.6%-34.2%)          83.5   (78.8%-88.2%)   78.4   (73.1%-83.7%)
 Women                                          90.0   (86.1%- 93.9%)                 34.1   (28.0%-40.2%)                       82.1   (77.1%- 87.1%)                        29.7   (23.8%-35.6%)          84.7   (80.0%-89.4%)   73.8   (68.1%-79.5%)
Race@
 White                                          90.1   (87.2%- 93.0%)                 33.8   (29.2%-38.4%)                       83.5   (79.9%- 87.1%)                        30.3   (25.8%-34.8%)          84.5   (81.0%-88.0%)   78.0   (73.9%-82.1%)
 Other                                          90.0   (82.9%- 97.1%)                 29.0   (18.3%-39.7%)                       82.6   (73.7%- 91.5%)                        20.3   (10.8%-29.8%)          81.2   (72.0%-90.4%)   65.2   (54.0%-76.4%)
Education level
 Less than high school                          82.3   (73.9%- 90.7%)                 11.4   ( 0.7%-21.8%)                       65.8   (55.3%- 76.3%)                         6.3   ( 0.9%-11.7%)          74.7   (65.1%-84.3%)   67.1   (56.7%-77.5%)
diploma
 High school graduate                           89.1   (83.9%- 94.3%)                 24.1   (16.9%-31.3%)                       86.1   (80.3%- 91.9%)                        20.4   (13.7%-27.1%)          83.9   (77.7%-90.1%)   72.3   (64.8%-79.8%)
 Some college                                   93.9   (89.8%- 98.0%)                 34.4   (26.3%-42.5%)                       87.8   (82.2%- 93.4%)                        30.5   (22.6%-38.4%)          87.0   (81.2%-92.8%)   78.6   (71.6%-85.6%)
 College graduate                               93.4   (89.0%- 92.8%)                 56.2   (47.4%-65.0%)                       86.8   (80.8%- 92.8%)                        51.2   (42.3%-60.1%)          86.8   (80.8%-92.8%)   83.5   (76.9%-90.1%)
Total                                           90.4   (87.7%- 93.1%)                 33.1   (28.8%-37.4%)                       83.4   (80.0%- 86.8%)                        28.8   (24.7%-32.9%)          84.0   (80.7%-87.3%)   76.1   (72.2%-80.0%)
* n=469.
+ Hemoglobin "A one C".
& Confidence interval.
@ Numbers for racial/ethnic groups other than white were too small for meaningful analysis.
========================================================================================================================================================================================================================================================

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