The Effectiveness of Diabetes Care Management in Managed Care
Published Online: May 07, 2009
Julie A. Schmittdiel, PhD; Connie S. Uratsu; Bruce Fireman, MA;
and Joe V. Selby, MD, MPH
The chronic care model highlights delivery system design as a key element in providing quality care to patients with chronic illness.1 One system design innovation that has taken hold in the past decade is the use of nonphysician care managers for selected patients with chronic illnesses such as diabetes mellitus. Clinical trials have examined the effect of care management (CM) programs2,3 (often led by nurses) on diabetes care quality and outcomes. Most have found positive associations between CM interventions and improved process measures (such as glycosylated hemoglobin [A1C] level testing rates) and patient satisfaction.2,4-7 It is controversial whether CM improves critical outcomes such as blood pressure and glycemic and lipid control.2,4-6,8-14 A recent effectiveness evaluation of CM found no association between the intensity of CM use and A1C level, blood pressure, or low-density lipoprotein cholesterol (LDL-C) level in the diabetic populations of 10 health plans and 71 provider groups.15 Almost all evaluations of CM to date have been randomized controlled trials.8,12,16,17 There have been few studies of how nurse CM programs and protocols from these trials translate into everyday care delivery settings18 or how they affect patient outcomes after implementation on a wide scale. Chronic condition CM usually is designed to target a small segment of higher-risk patients; however, there is little published information on the extent to which CM programs appropriately succeed in reaching their intended population.
Kaiser Permanente Northern California (KPNC) implemented a large-scale primarily nurse-led diabetes CM program beginning in 1999. More than 150 diabetes nurse care managers offered intensive counseling on medication management (including appropriate titration) and adherence, diet, and lifestyle to patients with diabetes referred to CM by their primary care physician. Care management was designed to help provide additional individualized patient support beyond primary care for improving self-management and cardiovascular disease (CVD) risk factor control. Control of glycemia was a central focus from the program’s inception; emphasis on blood pressure and lipid control was
added in later years. This program was designed to treat patients for 3 to 6 months and then to place the patients back into the primary care system once (ideally) CVD risk factors and self-management behaviors had improved.
The objectives of this study were 3-fold: (1) to describe the population of patients enrolled in this program, (2) to assess correspondence of program enrollment with stated entry criteria, and (3) to evaluate program effectiveness for improving A1C level, LDL-C level, systolic blood pressure (SBP), medication adherence, and appropriate treatment intensification.
This study was developed and approved by the steering committee of the Translating Research in Action for Diabetes (TRIAD) study15 and was conducted in KPNC, which is 1 of 6 TRIAD translational research centers. As an integrated healthcare delivery system, KPNC provides comprehensive medical care to a diverse population of approximately 3.2 million members in Northern California. Patients with diabetes were selected for the study from the KPNC diabetes registry19 if they were identified as having diabetes before December 31, 2002; were aged 20 to 85 years as of January 2003; and were continuously enrolled with an active drug benefit in January 2003. A small number of patients (n =
2609) who were likely to have type 1 diabetes mellitus (age <40 years as of January 1, 2003, and taking insulin only) were excluded. Initial SBP and A1C, LDL-C, and albumin levels for CM patients and for patients with diabetes not in CM were compared using the first value for 2003 found in the registry database. Patients were identified as CM participants if they had a diabetes CM entry date between January 1, 2003, and December 31, 2003, in the automated “Alert Note” CM database and had at least 1 day of enrollment in the program. Official eligibility criteria for the KPNC CM program state that patients entering diabetes CM should meet 1 or more of the following criteria: (1) an A1C level of at least 8.5%, (2) an albumin level exceeding 3.0 g/dL, or (3) a diabetes-related hospitalization or emergency department (ED) visit. All patients with diabetes were assessed for whether they met CM program entry criteria between July 1, 2002, and December 31, 2003.
Matching CM Patients to Control Subjects
To assess program effectiveness for improving SBP and A1C and LDL-C levels, as well as medication adherence and treatment intensification rates, the study included all CM patients who had been identified as having diabetes since at least December 2001 and who had been enrolled continuously with an active drug benefit from January 2002 through December 2005. These selection criteria allowed assessment of long-term intermediate outcomes and medication adherence before entering and after leaving CM. Because program participants could potentially differ from nonparticipants on a number of patient-level characteristics such as age or disease burden (as well as possibly the characteristics of their referring primary care physicians), the study used propensity score matching.20 This matching allowed for comparison of CM patients’ outcomes with those of similar patients who did not enter CM, while effectively controlling for differences in their baseline characteristics.20 Matched control subjects were selected from registry members who met the diabetes duration, health plan membership, and benefit criteria but who did not enter CM during 2003. For matching, all eligible patients were first assigned a propensity score (probability range, 0-1) for entering CM using logistic regression analysis and including the following predictors: age, sex, race/ethnicity, A1C level, albumin level, whether the patient had a diabetes-related hospitalization or ED visit in the prior year, comorbidity score (DxCG, Inc, Boston, Massachusetts) derived from hospital and ambulatory diagnoses during 2002,21 use of insulin, number of primary care visits in 2003, number of patients with diabetes in the patient’s primary care physician panel in 2003, and percentage of patients with diabetes in a primary care physician’s panel referred to CM in 2003. These variables were chosen because they reflected the official entry criteria for entering CM (and were likely to influence whether patients were referred into the program) or because they measured patient-level or physicianlevel characteristics that were likely to influence program entry. Each CM patient was matched to the control having the closest propensity score possible who also had an A1C reading during the quarter of 2003 in which the CM patient entered the program.
Adherence to Medication Regimens
Adherence to diabetes, hypertension, and hyperlipidemia medication regimens for 12 months before and after CM was calculated separately for each condition among CM patients and matched controls using KPNC prescription databases. For each medication class, the proportion of days between first and last prescription fills in the 12-month periods for which the patient did not have medication available was determined.22,23 Adherence was first calculated separately for each medication class and then was combined across all medications prescribed for a single condition, weighing each by the interval from first to last prescription fill in the period. Consistent with prior findings in this setting,24 poor adherence for each condition was defined as a weighted nonadherence measure of at least 20% across all medications prescribed for the condition.
Treatment intensification during 12 months following the start of CM was assessed for each CM patient and his or her matched control using prescription fills during 3 months before and 3 months after the first above target measurement in the period. Intensification was defined as any 1 of the following 3 occurrences: (1) an increase in the number of drug classes, (2) an increase in the daily dose of at least 1 ongoing drug class, or (3) a switch to a medication in a different drug class. A new insulin regimen was considered treatment intensification for hyperglycemia; titration of insulin dosages after insulin initiation could not be observed in the pharmacy database. Details on this method are available elsewhere.24
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