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Quality Measure Attainment in Patients With Type 2 Diabetes Mellitus
Marie-Hélène Lafeuille, MA; Amanda M. Grittner, MA; Jonathan Gravel, MSc; Robert A. Bailey, MD; Silas Martin, MS; Lawrence Garber, MD; Mei Sheng Duh, MPH, ScD; and Patrick Lefebvre, MA
Participating Faculty: Opportunities for Improving Attainment of Quality Measures in Patients With Type 2 Diabetes Mellitus

Quality Measure Attainment in Patients With Type 2 Diabetes Mellitus

Marie-Hélène Lafeuille, MA; Amanda M. Grittner, MA; Jonathan Gravel, MSc; Robert A. Bailey, MD; Silas Martin, MS; Lawrence Garber, MD; Mei Sheng Duh, MPH, ScD; and Patrick Lefebvre, MA
Objectives: This study examined the demographics, comorbidities, clinical characteristics, and treatments of people with type 2 diabetes mellitus (T2DM) treated with metformin and sulfonylurea as well as an elderly subgroup. Achievement of predefined quality measure goals (glycated hemoglobin [A1C], blood pressure [BP], low-density lipoprotein cholesterol [LDL-C], body mass index [BMI]) and their association with diabetes-related healthcare costs were assessed.

Study design: The study applied a retrospective longitudinal cohort design.

Methods: Health insurance claims and electronic medical records from 14,532 adults with T2DM (2007- 2011) were used to identify a sample receiving metformin and sulfonylurea (MET+SU) concomitantly. The index date was the first dispensing of MET+SU after 6 months of eligibility. Clinical characteristics were assessed during baseline. Quality measure attainment (A1C <8%, BP <140/90 mm Hg, LDL-C level <100 mg/dL, BMI <30 kg/m2), was evaluated during the 12 months following the index date. Association between attainment and diabetes-related costs was evaluated using non-parametric bootstrap methods adjusting for imbalance in baseline characteristics between cohorts.

Results: Among 2044 patients, including 1283 patients 65 years and older, hyperlipidemia, hypertension, and cardiovascular disease were the most common baseline comorbidities. Quality measure goal attainment was 63.9% for A1C, 33.1% for BP, 68.2% for LDL-C level, and 34.4% for BMI, and was associated with significantly lower diabetes-related costs per patient per year compared with nonattainment (adjusted mean cost differences: –$1445 for A1C; –$1218 for BMI; –$2029 for A1C and BMI; –$2073 for A1C, BMI, and BP; all P <.05).

Conclusion: This study highlights the high incidence of comorbidities and potential financial implications of attaining T2DM quality outcomes.

(Am J Manag Care. 2014;20:S5-S15)
The total economic burden of diabetes in the United States in 2012 was estimated at $245 billion, a 21% increase from 2007.1 The prevalence of diabetes increases with age and reaches its peak in the population aged 60 to 74 years.2 Management of diabetes is challenging, especially in an elderly population due to complex comorbid medical issues and a generally lower functional status.3

According to guidelines for diabetes monitoring and treatment, glycated hemoglobin (A1C), blood pressure (BP), lowdensity lipoprotein cholesterol (LDL-C) level, and weight/body mass index (BMI) have been identified as important interrelated quality measures in the treatment and monitoring of type 2 diabetes mellitus (T2DM).4 The Centers for Medicare & Medicaid Services (CMS) has set specific treatment goals for particular clinical parameters that accountable care organizations participating in its Medicare Shared Savings Program have to achieve when treating patients with diabetes: A1C: 8%, BP: 140/90 mm Hg, LDL-C level: 100 mg/dL.5-7 The Medicare Shared Savings Program is an initiative under the Patient Protection and Affordable Care Act. CMS records a provider’s score for achieving these measures to calculate the part of cost savings that it will share with the provider. A BMI less than 30 kg/m2 is an emerging quality measure for diabetes, because a higher BMI indicates obesity, a major risk factor for T2DM.8 This threshold is already being applied by the Clinical Advisory Committee of Better Health Greater Cleveland, a network of primary care practice partners responsible for Cuyahoga County in northeastern Ohio.9

In addition to improving diabetes control to minimize the risk of complications and to potentially improve the well-being of patients with T2DM, achievement of such predefined quality measure goals may also have important economic implications since improved diabetes control leads to fewer disease complications, which can be costly. A study found that the average lifetime medical costs of treating T2DM, including diabetic complications, totaled $85,200, with 53% due to treating diabetic complications.10 To the authors’ knowledge, despite the importance of these quality measures for diabetes control and treatment and their potential importance for the management of the economic burden of T2DM, there are no studies that use real-world data from patients with T2DM to assess the achievement of these quality measure goals and its association with diabetes-related costs.

The objective of this study was to examine the demographic and clinical characteristics and the achievement of predefined quality measure goals in a T2DM population receiving metformin and sulfonylurea, as well as in an elderly subgroup of this population, and to assess the association of goal attainment with diabetes-related healthcare costs.

Metformin and sulfonylurea are well-established core therapies for controlling hyperglycemia in patients with T2DM.11 Adding a sulfonylurea is one of the treatment options available for metabolic management if metformin and lifestyle changes alone fail to achieve or sustain glycemic control. Hence, patients who receive this combination therapy can be considered as having faced challenges in controlling their hyperglycemia. Achieving predefined quality measure goals may therefore have particular effects on clinical outcomes and healthcare cost for this patient population.

Methods

Data Source


The study used data from health insurance claims and electronic medical records from the Reliant Medical Group (RMG) database covering the 5-year period from January 1, 2007, through December 31, 2011. RMG is a large nonprofit multispecialty group practice that provides comprehensive care for patients; it has a total of over 1 million patient visits each year to more than 250 physicians practicing across 20 locations throughout central Massachusetts.

The data were de-identified in compliance with the Health Insurance Portability and Accountability Act of 1996 to preserve patient confidentiality. Database elements used for this study included longitudinal, memberlinked medical claims, pharmacy claims, enrollment records (including patient demographics), laboratory results (eg, A1C), and clinical measures (eg, weight and BP).

Study Design and Patient Selection

A retrospective longitudinal landmark cohort design was used (Figure 1). Adult patients with at least 1 diagnosis of T2DM (International Classification of Diseases, 9th Revision [ICD-9]= 250.x0 or 250.x2) who were being treated concomitantly with metformin and a sulfonylurea (eg, chlorpropamide, glimepiride, glipizide, glyburide, tolazamide, and tolbutamide) after at least 6 months of continuous eligibility (baseline period) were included in the study population. The index date was defined as a patient’s first day of a metformin and sulfonylurea prescription. Patients had to be continuously eligible for at least 12 months after the index date (landmark period). Patients who were diagnosed with type 1 diabetes mellitus or treated with insulin (with or without other oral antihyperglycemic agents in combination) during the baseline period were excluded from the study population.

From the real-world sample of 14,532 patients with T2DM, 2666 were being treated with a combination of metformin and sulfonylurea. Applying subsequent inclusion and exclusion criteria resulted in an overall study population of 2044 patients, including 1283 patients 65 years and older.

Study Outcomes

Evaluation of Quality Measures and Goal Attainment

Quality measures (A1C, BP, LDL-C level, BMI) were evaluated during the landmark period and reported for the overall population and the elderly subgroup. Quality measure goal attainment was defined as having no values equal to or higher than the predefined threshold during the landmark period. The individual thresholds were:
  • A1C: 7%, 8%, and 9%
  • BP: 140/90 mm Hg
  • LDL-C level: 100 mg/dL
  • BMI: 30 kg/m2
The combined thresholds were:
  • A1C: 8%; BP: 140/90 mm Hg; LDL-C level: 100 mg/dL
  • A1C: 7%; BP: 140/90 mm Hg; LDL-C level: 100 mg/dL
  • A1C: 8%; BMI: 30 kg/m2
  • A1C: 8%; BMI: 30 kg/m2; BP: 140/90 mm Hg


Quality Measure Goal Attainment and Healthcare Costs

Evaluated during the observation period, diabetes-related medical healthcare costs were identified through claims associated with a diagnosis for diabetes (ICD-9 = 250.x0 or 250.x2), whereas diabetes-related pharmacy costs were defined as claims for antihyperglycemic agents. Medical costs were further broken down into emergency department costs, inpatient costs, and outpatient/other visits, according to their recorded medical cost category.

Statistical Analyses

Univariate descriptive statistics were generated to describe the baseline demographics, clinical characteristics, and costs of the overall population and an elderly subgroup (≥65 years of age), as well as the evaluation of quality measures during the landmark period, including mean ± standard deviation for continuous data and relative frequencies for categorical data.

Costs were reported in US dollars (2011) per patient per year (PPPY) for quality measure goal achievers versus non– goal achievers. Unadjusted and adjusted cost differences were estimated using (a) generalized linear models (GLMs) with a log link and gamma distribution; or (b) 2-part models (for cost components with a portion of zero values greater than 5%), where the first part was a logistic model and the second part was a GLM model with a log link and a gamma distribution. The gamma distribution was chosen, as it is recognized to fit well-skewed healthcare cost data.12 Controlling factors included age, sex, year of index date, race, payer type, and Charlson Comorbidity Index. As baseline diabetes-related comorbidities may contribute to goal achievement, it was decided not to adjust for them in the multivariate analysis to avoid removing the explanatory effect of the goal achievement variable. Statistical differences between groups (P values) and 95% confidence intervals were calculated using nonparametric bootstrap re-sampling techniques with 499 replications to ensure parameter stability.13 Significance level was set at a 2-sided α value of 0.05.

Results

Baseline Population Characteristics

Demographics, clinical characteristics, and costs at index date/baseline are presented in Table 1.

Mean (median) age at index date was 66.6 (69.0) years in the overall study population and 74.6 (74.0) years in the elderly population subgroup. The incidence of macrovascular comorbidities, including cardiovascular disease and chronic heart failure, was higher than that of microvascular comorbidities, such as nephropathy, neuropathy, and retinopathy, in both the overall study population and the elderly population subgroup. The most common comorbidities were hyperlipidemia (overall population, 73.9%; elderly subgroup, 78.1%), hypertension (66.5% and 74.2%, respectively), and cardiovascular disease (25.5% and 33.4%, respectively). Compared with the overall population, the elderly population subgroup had higher incidence of most of the macrovascular and microvascular complications and other comorbidities. Antihypertensives were prescribed to 67.2% of all patients and 75.1% of those 65 years and older. Loop diuretics accounted for 10.5% and 13.6% and non-loop diuretics accounted for 21.1% and 24.5% in the total and elderly populations, respectively.

Evaluation of Quality Measures and Goal Attainment

Figures 2A and 2B present the evaluation of quality measures and goal attainment. Figure 2A shows that in the overall study population, mean A1C was 7.5%, mean BP was 131.8/72.8 mm Hg, mean LDL-C level was 85.2 mg/dL, and mean BMI was 32.7 kg/m2. In the overall study population, 63.9% achieved the A1C goal of less than 8%, 27.2% the A1C goal of less than 7%, 33.1% the BP goal (<140/90 mm Hg), 68.2% the LDL-C level goal (<100 mg/dL), and 34.4% the BMI goal (<30 kg/m2).

 
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