Managed Care - February 2008 - (Page 50) Outcome measures The study examined multiple quality indicators exemplifying evidence-based medicine and medication adherence for nine chronic conditions that are prevalent and costly to society: pediatric asthma, adult asthma, CHF, CAD, depression, diabetes, hyperlipidemia, hypertension, and migraine. Patients were identified by ICD9 codes in claims incurred before the index date. Guideline adherence was estimated as the proportion of patients with at least one prescription fill of a recommended medication during the period 180 days before and 90 days after the index date. To calculate medication adherence, the medication possession ratio (MPR) was computed for study subjects with at least two fills for the identified medication during the period 180 days before and 90 days after the index date. MPR was defined as the ratio of days supplied of one or more medication refills, excluding the days supplied from the last prescription fill, divided by the time elapsed between the first and last fill date. The MPR threshold of 70 percent was used to classify adherent versus nonadherent subjects. RESULTS Most (94 percent) enrollees were in the commercial segment of the health plan, 2 percent were under Medicaid, and 4 percent were under Medicare. Eight percent of enrollees were over age 65 years, and 24 percent were under age 18. While women constituted half of the enrollees in total and in the commercial plan, they made up nearly 60 percent of both the Medicaid and Medicare enrollee population (Table 1). Adherence to evidence-based practice guidelines examined in this study averaged approximately 59 percent (Table 2). As found in other studies, levels of adherence to guidelines varied across conditions and measures (BCG 2003). Use of angiotensin-converting enzyme (ACE) inhibitors was found in only 35 percent of patients with coronary artery disease, and just 36 percent of patients with hyperlipidemia had filled a prescription for a statin or appropriate alternative therapy. Analyzing patient medication adherence, we found high rates in patients with diabetes, of whom 80 percent had filled at least one prescription for an oral antidiabetic medication. Among patients with depression, 85 percent of patients had filled a prescription for an antidepressant and 56 percent had filled a prescription for either selective serotonin reuptake inhibitors (SSRIs) or serotonin & norepinephrine reuptake inhibitors (SNRIs). For asthma, 78 percent of adult persistent asthma patients and nearly all of the pediatric persistent asthma patients (97 percent) filled a prescription for an inhaled corticosteroid. Patient medication nonadherence rates across all the conditions studied averaged 26 percent, with a range of 11 percent to 42 percent. Nonadherence with a variety of hypertension medications was 11 percent. Patients with diabetes had nonadherence rates that ranged from 16 percent to 25 percent. More than a quarter of patients with depression were non-adherent with their antidepressant, while 37 percent of adults and 42 percent of children with persistent asthma (high-utilizers of medical service) were not compliant with their inhaled corticosteroid therapy. Similar results were observed for patients with CHF, CAD, and hyperlipidemia (Table 3). DISCUSSION These data offer another look at the prevalent medication adherence problem that exists throughout our health care system. Past research has demonstrated similar findings at a more condition-specific level. A recent study of diabetic patients found nonadherence rates ranging from 13 percent to 64 percent (Lee 2006). Patients with major depression were discovered to have nonadherence rates around 50 percent after three months (Vergouwen 2002). An examination of patients with at least one of four cardiovascular-related conditions (coronary heart disease, hypertension, diabetes, and hyperlipidemia) found an overall nonadherence rate of 40 percent (Gazmararian 2006). Also, a study of six classes of chronic medications revealed nonadherence rates of 43 percent for calcium channel blockers, 35 per- TABLE 1 Member age and gender by insurance type Members between Oct. 1, 2002 and Dec. 31, 2004 Total members: Commercial (N=4,330,240) (n=4,070,426) 24% 20% 28% 20% 8% 51% 92% 98% 99% 98% 56% 51% Medicaid (n=86,605) 8% 2% 1% 1% 1% 58% Medicare (n=173,210) 0% 0% 0% 1% 43% 58% Age group 0–17 18–34 35–49 50–64 65+ Female 50 MANAGED CARE / FEBRUARY 2008
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