Local population characteristics and hemoglobin A1c testing rates among diabetic medicare beneficiaries

The frequency of testing for glycated haemoglobin, HbA1c, is linked to the probability of achieving target levels in patients with suboptimally controlled diabetes mellitus

Background We previously showed, in patients with diabetes, that >50% of monitoring tests for glycated haemoglobin (HbA1c) are outside recommended intervals and that this is linked to diabetes control. Here, we examined the effect of tests/year on achievement of commonly utilised HbA1c targets and on HbA1c changes over time. Methods Data on 20,690 adults with diabetes with a baseline HbA1c of >53 mmol/mol (7%) were extracted from Clinical Biochemistry Laboratory records at three UK hospitals. We examined the effect of HbA1c tests/year on (i) the probability of achieving targets of ≤53 mmol/mol (7%) and ≤48 mmol/mol (6.5%) in a year using multi-state modelling and (ii) the changes in mean HbA1c using a linear mixed-effects model. Results The probabilities of achieving ≤53 mmol/mol (7%) and ≤48 mmol/mol (6.5%) targets within 1 year were 0.20 (95% confidence interval: 0.19-0.21) and 0.10 (0.09-0.10), respectively. Compared with four tests/year, having one test or more than four tests/year were associated with lower likelihoods of achieving either target; two to three tests/year gave similar likelihoods to four tests/year. Mean HbA1c levels were higher in patients who had one test/year compared to those with four tests/year (mean difference: 2.64 mmol/mol [0.24%], p<0.001). Conclusions We showed that ≥80% of patients with suboptimal control are not achieving commonly recommended HbA1c targets within 1 year, highlighting the major challenge facing healthcare services. We also demonstrated that, although appropriate monitoring frequency is important, testing every 6 months is as effective as quarterly testing, supporting international recommendations. We suggest that the importance HbA1c monitoring frequency is being insufficiently recognised in diabetes management.

Association of diabetes diagnosis with dietary changes and weight reduction

BACKGROUND

Lifestyle modifications are associated with better outcomes for patients with diabetes. Patients' awareness of having diabetes may promote lifestyle changes, but there is limited evidence to support this assertion. This study examined whether a report of physician-diagnosed diabetes is associated with dietary changes and efforts to lose weight.

METHODS

Cross-sectional comparison of individuals with and without diabetes or prediabetes diagnosis, matched on glycosylated hemoglobin (HbA1c) level, socio-demographic characteristics, and health status using propensity-score matching analysis. Non-pregnant US adult participants (aged 20 and older with an HbA1c level between 5.7% and 7.5%) in the 1999-2014 National Health and Nutrition Examination Survey were included (N = 10,781).

RESULTS

Compared with matched controls who did not report having diabetes or prediabetes (N = 1,769), persons with a diagnosis of diabetes or prediabetes (N = 1,769) reported less sugar consumption (14.9 grams [95% CI: 8.9 to 21.0]); less carbohydrate consumption (11.6 grams [95% CI: 1.7 to 21.5]); higher rates of trying to lose weight (12.3 percentage points [95% CI: 5.3 to 19.2]); and a greater one-year weight reduction (4.8 ounces [95% CI: 3.3 to 6.4]).

CONCLUSIONS

Awareness of a diagnosis of diabetes or prediabetes from a health profession is associated with the uptake of recommended life-style modifications.

Consistency of Hemoglobin A1c Testing and Cardiovascular Outcomes in Medicare Patients With Diabetes

Background

Annual hemoglobin A1c testing is recommended for patients with diabetes mellitus. However, it is unknown how consistently patients with diabetes mellitus receive hemoglobin A1c testing over time, or whether testing consistency is associated with adverse cardiovascular outcomes.

Methods and Results

We identified 1 574 415 Medicare patients (2002–2012) with diabetes mellitus over the age of 65. We followed each patient for a minimum of 3 years to determine their consistency in hemoglobin A1C testing, using 3 categories: low (testing in 0 or 1 of 3 years), medium (testing in 2 of 3 years), and high (testing in all 3 years). In unweighted and inverse propensity‐weighted cohorts, we examined associations between testing consistency and major adverse cardiovascular events, defined as death, myocardial infarction, stroke, amputation, or the need for leg revascularization. Overall, 70.2% of patients received high‐consistency testing, 17.6% of patients received medium‐consistency testing, and 12.2% of patients received low‐consistency testing. When compared to high‐consistency testing, low‐consistency testing was associated with a higher risk of adverse cardiovascular events or death in unweighted analyses (hazard ratio [HR]=1.21; 95% CI, 1.20–1.23; P<0.001), inverse propensity‐weighted analyses (HR=1.16; 95% CI, 1.15–1.17; P<0.001), and weighted analyses limited to patients who had at least 4 physician visits annually (HR=1.15; 95% CI, 1.15–1.16; P<0.001). Less‐consistent testing was associated with worse results for each cardiovascular outcome and in analyses using all years as the exposure.

Conclusions

Consistent annual hemoglobin A1c testing is associated with fewer adverse cardiovascular outcomes in this observational cohort of Medicare patients of diabetes mellitus.

The relationship of regional hemoglobin A1c testing and amputation rate among patients with diabetes

Objective The risk of leg amputation among patients with diabetes has declined over the past decade, while use of preventative measures-such as hemoglobin A1c monitoring-has increased. However, the relationship between hemoglobin A1c testing and amputation risk remains unclear. Methods We examined annual rates of hemoglobin A1c testing and major leg amputation among Medicare patients with diabetes from 2003 to 2012 across 306 hospital referral regions. We created linear regression models to study associations between hemoglobin A1c testing and lower extremity amputation. Results From 2003 to 2012, the proportion of patients who received hemoglobin A1c testing increased 10% (74% to 84%), while their rate of lower extremity amputation decreased 50% (430 to 232/100,000 beneficiaries). Regional hemoglobin A1c testing weakly correlated with crude amputation rate in both years (2003 R = -0.20, 2012 R = -0.21), and further weakened with adjustment for age, sex, and disability status (2003 R = -0.11, 2012 R = -0.17). In a multivariable model of 2012 amputation rates, hemoglobin A1c testing was not a significant predictor. Conclusion Lower extremity amputation among patients with diabetes nearly halved over the past decade but only weakly correlated with hemoglobin A1c testing throughout the study period. Better metrics are needed to understand the relationship between preventative care and amputation.

Does Rapid Diffusion of HbA1c Testing Affect Amputation Rates?

BACKGROUND

The association of speed of diffusion of Hemoglobin A1C (hbA1c) testing with temporal changes in outcomes of primary importance to patients with diabetes, such as amputation, remains an issue of debate. We investigated these correlations.

METHODS

We performed a retrospective cohort study of diabetics, based on Medicare fee-for-service claims data from 2002 to 2012. We examined the association of the rate of diffusion of HbA1c testing with changes in amputation rates. Our unit of analysis was the hospital referral region (HRR), a definition of tertiary care markets defined in the Dartmouth Atlas of Health Care.

RESULTS

From the 11 096 270 diabetics followed in our study for a mean follow-up of 4.1 years, 106 340 (0.96%) underwent lower extremity amputations. The speed of diffusion of HbA1c testing had a moderate association with the speed of diffusion of lower extremity amputations, after adjusting for multiple factors including baseline regional amputation and testing rates (adjusted difference, -0.7%; 95% confidence interval, -1.0% to -0.3%). The risk-adjusted HRR-level speed of diffusion of testing demonstrated significant correlation with the risk-adjusted HRR-level diffusion of amputations (r = .250, P < .001).

CONCLUSIONS

We observed a moderate association of the speed of diffusion of HbA1c testing with the speed of diffusion of lower extremity amputations among Medicare patients with diabetes. Improvements in performance on quality metrics such as HbA1c testing may not immediately translate into tangible patient outcomes.

HbA1c overtesting and overtreatment among US adults with controlled type 2 diabetes, 2001-13: observational population based study

STUDY QUESTION

What is the extent and effect of excessive testing for glycated hemoglobin (HbA1c) among adults with controlled type 2 diabetes?

METHODS

A retrospective analysis of data from a national administrative claims database included commercially insured individuals in the USA, 2001-13. Study patients were aged 18 years or older, had type 2 diabetes with stable glycemic control (two consecutive tests showing HbA1c<7.0% within 24 months), did not use insulin, had no history of severe hypoglycemia or hyperglycemia, and were not pregnant. HbA1c testing frequency was measured within 24 months after the second (index) HbA1c test, and classified as guideline recommended (≤ 2 times/year), frequent (3-4 times/year), and excessive (≥ 5 times/year). Changes in treatment regimen were ascertained within three months of the index test.

STUDY ANSWER AND LIMITATIONS

Of 31,545 patients in the study cohort (mean age 58 years; mean index HbA1c 6.2%), HbA1c testing frequency was excessive in 6% and frequent in 55%. Despite good glycemic control at baseline, treatment was further intensified by addition of glucose lowering drugs or insulin in 8.4% of patients (comprising 13%, 9%, and 7% of those tested excessively, frequently, and per guidelines, respectively; P<0.001). Compared with guideline recommended testing, excessive testing was associated with treatment intensification (odds ratio 1.35 (95% confidence interval 1.22 to 1.50)). Excessive testing rates remained unchanged in 2001-08, but fell significantly after 2009. The odds of excessive testing was 46% lower in 2011 than in 2001-02. The study population is not representative of all US patients with type 2 diabetes because it was restricted to commercially insured adults with stable and controlled diabetes not receiving insulin treatment. The study design did not capture the underuse of HbA1c testing.

WHAT THIS STUDY ADDS

In this US cohort of adults with stable and controlled type 2 diabetes, more than 60% received too many HbA1c tests, a practice associated with potential overtreatment with hypoglycemic drugs. Excessive testing contributes to the growing problem of waste in healthcare and increased patient burden in diabetes management.

FUNDING, COMPETING INTERESTS, DATA SHARING

NDS and RGM are funded partly by the Agency for Healthcare Research and Quality (R18HS18339) and AcademyHealth Delivery System Science Fellowship (2013), respectively. No competing interests declared. Additional data are available from mccoy.rozalina@mayo.edu.