This cross-sectional, retrospective study was conducted to assess and benchmark adherence to nationally recognized treatment guidelines and medication adherence among veterans with the following common chronic conditions: asthma, chronic obstructive pulmonary disease (COPD), coronary artery disease (CAD), diabetes, heart failure (HF), and hyperlipidemia (HL). These conditions were chosen based on their high prevalence and the availability of nationally recognized guidelines for treating them. This study sought to assess select quality indicators, medication use and adherence, and health care utilization. This study received local institutional review board approval.
Study site and data source
The study site is one of the most complex health care facilities in the Department of Veterans Affairs and is a Clinical Referral Level 1a facility. The facility is a 569-bed, tertiary care, teaching hospital with 3 outpatient clinics and 5 community-based outpatient clinics. The study site is a highly affiliated teaching hospital, providing a full range of patient care services with state-of-the-art technology. Approximately 112,500 veterans and active-duty service members receive comprehensive health care through primary, tertiary, and long-term care in numerous disciplines. There are over 3500 employees involving a wide spectrum of professional, technical, and administrative occupations. The organization provides medical, surgical, psychiatric, geriatric, and extended care services in a variety of acute, outpatient, long-term care, and residential settings.
The data utilized for this study were electronic medical records maintained in the Veterans' Health Information System Technology Architecture (VistA) database at the James A. Haley Veterans' Hospital in Tampa, Florida, for patients who are seen at this facility. VistA supports both ambulatory and inpatient care and includes computerized order entry, bar code medication administration, electronic prescribing, and clinical guidelines. Data were de-identified to protect patients' privacy.
Patients of the James A. Haley Veterans' Hospital were selected for the study who had at least 1 of the target conditions (asthma, COPD, CAD, diabetes, HF, HL) based on the disease-specific criteria described in . The time period to identify patients was from January 2002 through June 2006. In order to include current patients who have sufficient data to help ensure relevance, patients were included if they had at least 6 months of data available after they had been identified with one of the conditions and maintained eligibility for services through December 31, 2006. The first identification of any condition (index date) was based on the first occurrence of the condition-specific inclusion criterion and could have occurred prior to 2006 or in the first 6 months of 2006. The first 6 months of 2006 was utilized to allow newly diagnosed patients or patients new to VHA center coverage to be included in the sample because these patients would still have a minimum of 6 months remaining in the year to be assessed at this facility.
Disease-Specific Criteria for Inclusion in the Study
Measures and data analysis
All results were derived from 2006 data in order to benchmark annual care in the most recent year available at the time. Analyses were conducted using SAS version 9.1 (SAS Institute Inc., Cary, NC). Data were summarized with descriptive statistics for each of the conditions; no hypothesis testing was undertaken.
Quality of care measures were determined for asthma, COPD, and diabetes in 2006. These conditions were chosen based on the availability of current national guidelines to assess overall indicators of quality of care received or other claims-based markers available that could provide an indication of quality. The measure of quality of care for asthma included the percentage of patients with at least 4 short-acting beta-agonist (SABA) prescription fills, which was chosen because the frequent use of rescue medications has been shown to increase the risk of exacerbation.8,9
This measure is not definitive but rather intended to identify what percent of patients are potentially uncontrolled requiring further assessment. The measures of quality of care for COPD included the percentage of patients with a Level II (COPD-related hospitalization) or Level III exacerbation (respiratory failure).10,11
Diabetes measures of quality of care were based on American Diabetes Association guidelines and included the percentage of patients with at least 1
A1c test and those with A1c <
7% at their most recent measurement, patients with at least 1 low-density lipoprotein (LDL) test and those with LDL <
mg/dl at their most recent measurement, as well as the percentage of patients who received the minimum acceptable number of A1c tests of ≥
2 in a year.12
Only diabetes patients with a full year of data in 2006 were evaluated for these measures to accurately reflect the guidelines.
The percentage of patients who filled a prescription for any acceptable therapy during the most recent 6 to 12 months (based on sample selection) was calculated for each chronic disease. Any acceptable therapy, shown in , was defined for each disease according to disease-specific national treatment guidelines.8,10–11,13–16
Medication use for diabetes was calculated for all patients on medications and then more specifically for oral diabetes medications.
Persistence was calculated using the proportion of days covered (PDC), defined as the total number of days' supply for 2006 divided by the number of days between first fill and the end of the year. Patients must have had at least 1 fill in 2006 for the medication of interest and were required to have at least 6 months of data from the first prescription fill to the last day of available data in order to be included in the persistence analyses. A minimum of 6 months post initial fill is required to help ensure each patient has enough time downstream to adequately contribute to overall condition metrics. The percentage of patients with persistence ≥80% was determined and patients meeting this criterion were considered persistent with their medications.
Compliance for patients refilling medication was calculated as the medication possession ratio (MPR), defined as the total number of days' supply between the first and last fills (not including the last fill's supply) divided by the total number of days between the first and last fills for any acceptable therapy per the guidelines. Like persistence, MPR was calculated only for patients with at least 6 months of data from the first prescription fill in 2006 to the last day of December 2006 to help ensure relevance, especially because 2 fills are required for this compliance metric. The percentage of patients with a MPR ≥
80% was determined for each condition and patients meeting this criterion were classified as compliant with their medications.
The inability to obtain accurate data on days' supply of therapy for inhaled products affected the definition of any acceptable therapy for asthma and COPD per the treatment guidelines. For asthma and COPD inhaled products, package inserts and a pharmacist review were used to calculate days' supply for inhaled corticosteroids (ICS), ICS plus long-acting beta-agonists (LABA), SABA plus anticholinergic products, and LABA alone. Because of limitations in the days' supply data, cromolyn was not included as any acceptable therapy for asthma. Also, for diabetes, persistence and compliance rates were only calculated for oral diabetes medications because of unreliable data for insulin.
Health care utilization
Measures of health care utilization included the percentage of patients with at least 1 emergency room (ER) visit, at least 1 hospitalization, at least 1 any outpatient visit, at least 1 pharmacy claim, and the mean number of visits by type. Both all-cause and disease-related health care utilization were determined. Medical records with a primary diagnosis of the condition of interest and pharmacy claims with National Drug Codes mapped to the disease classes described in were considered to be disease-related. Because follow-up periods varied from 6 to 12 months among patients, data on health care utilization were annualized for those patients with less than 12 months of available data in 2006.