Therapy Modifications in Response to Poorly Controlled Hypertension, Dyslipidemia, and Diabetes Mellitus

Context What actions do health care providers take for patients with poorly controlled cardiovascular risk factors? Content This large retrospective cohort study from Kaiser Permanente of Northern California found that, within a 6-month period, most patients received therapy modifications for the following poorly controlled risk factors: systolic blood pressure (64%), diastolic blood pressure (71%), low-density lipoprotein cholesterol level (56%), and hemoglobin A1c level (66%). The most frequent modifications were adding drugs and increasing dosages. Cautions We do not know how often patient preferences or suboptimal adherence influenced treatment decisions. The study did not directly link therapy modifications to clinical outcomes. The Editors Despite strong evidence that pharmacotherapeutic interventions contribute to preventing cardiovascular events in high-risk individuals (1-5), risk factor control remains suboptimal (6-9) and medications to reduce risk factors seem to be underused (10, 11). Underuse of evidence-based medications in chronic disease care may be partly due to clinical inertia (12) by physicians and health care systems. As such, it represents a possible avenue for quality improvement in health care (13, 14). The Health Plan Employer Data and Information Set (HEDIS) has developed measures to assess health plan and individual physician performance (15) that are based directly on the proportions of high-risk patients whose low-density lipoprotein (LDL) cholesterol levels, hemoglobin A1c levels, and blood pressure are in control. Although such measures may identify important deficiencies in quality (16) and are directly related to the health status of patients, they may be confounded by population differences in case mix and therefore cannot distinguish between a patient who is receiving poor care and a patient who is being appropriately treated but who either does not adhere to treatment recommendations or has particularly severe disease that is less responsive to treatment (17). Ideally, quality measures should reflect whether physicians and systems deliver appropriate or optimal care. Provider responses to poorly controlled risk factor levels, such as intensification of either behavioral therapy or pharmacotherapy, have recently been proposed as tightly linked process indicators of quality. Solid evidence suggests that these processes of care are directly linked to improved patient outcomes (18, 19). Such tightly linked process measures might be more clinically relevant than the levels of either testing or control (18). Higher testing rates have not been shown to be associated with better clinical control (7, 19). To better understand the potential utility and the feasibility of measuring therapy modifications in response to poor risk factor control as an additional measure of quality, we examined the frequency and predictors of therapy modifications in response to poorly controlled hypertension, dyslipidemia, and diabetes in a large managed care population. Methods Study Participants Description of the Study Population We performed a retrospective cohort study within an 18-month period from 1 July 2002 to 31 December 2003 of all members of Kaiser Permanente Medical Care Program of Northern California who were older than 20 years of age. Kaiser Permanente Medical Care Program is a fully integrated health care delivery system that provides comprehensive medical care to more than 3 million members. Members comprise approximately 30% of the northern California population and are demographically representative of the population (20). Primary care physicians, who worked with specialty care, health education, and nutrition education staff located in close proximity, followed most patients. Many primary care teams included care managers and either nurses or pharmacists, to whom patients with poor control could be directly referred. All services were covered benefits. Diagnostic Criteria We searched clinical databases, including inpatient and ambulatory diagnoses, ambulatory blood pressure measurements, laboratory results, and prescriptions for the 18-month period before 31 December 2003, to identify all patients categorized as having hypertension, dyslipidemia, diabetes mellitus, or a combination of these conditions and to assess modifications in therapy in response to poor control. Criteria used to identify each condition (Appendix Table 1) have been described previously (21). Previous studies have documented the accuracy of the clinical databases used in our study for several diagnoses, including diabetes, coronary artery disease (CAD), and stroke (22, 23). Diabetes diagnoses, myocardial infarction, and stroke are confirmed at chart review in 98%, 99%, and 75% of cases, respectively. Study Cohort To assess therapy modifications in response to poorly controlled hypertension, dyslipidemia, or diabetes mellitus, we identified patients who met criteria for poor control of 1 condition or more at some point during the study period. Appendix Table 2 details our definitions of poor control. We did not include patients with moderately elevated risk factors because initial lifestyle modification is often appropriate for these participants (4, 5), so pharmacotherapeutic interventions may not be warranted. To allow a complete 6-month follow-up, we extended observation into 2004 for those whose poor control was first identified in the second half of 2003. We excluded members who were not continuously enrolled 4 months before and 6 months after the date of the defining measure of poor control because we did not have adequate time for observation (Figure). We also excluded patients with diabetes who were already treated with insulin therapy, because day-to-day adjustments in insulin dosage cannot be reliably identified from automated data sources. Figure. Flow of participants in the study. BP Measurements Therapy Modifications in Response to Poor Control On the basis of previous definitions of tightly linked quality measures (17), we defined a potential therapy modification as an increase in the number of drug classes, increased dosage of 1 medication or more, or a switch to another medication in a different therapeutic class. We did not treat switches to medications in the same therapeutic class as a therapy modification, unless the daily dose of the new agent represented an increase in bioequivalent dose compared with the previous agent, because a switch could be in response to side effects rather than an intensification of therapy. Other outcomes included a return to control without therapy modification, which was based on the last risk factor measurement recorded during the 6-month period; a return to near control (Appendix Table 2); and no therapy modification with either no return to control or no further measurement. This last category included patients with no follow-up visit during the interval. Recognizing that physicians may sometimes opt for nonpharmacologic recommendations for an elevated risk factor value, we created an outcome called appropriate care, defined as either a therapy modification or return to control without therapy modification within 6 months. We also examined responses within 3 months. Pharmacologic Management We defined pharmacologic therapy from prescriptions filled during the 4 months before and the 6 months after the first abnormal risk factor measure. We grouped drugs by drug codes into therapeutic classes, with 7 classes for hypertension (thiazide diuretics, other diuretics, -blockers, calcium-channel blockers, angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, and other antihypertensive agents), 5 classes for dyslipidemia (statins, fibric acid derivatives, niacin, bile acid resins, and other lipid-lowering agents), and 5 classes for diabetes mellitus (insulin, sulfonylureas, metformin, thiazolidinediones, and other diabetes-related medications). We recorded daily dosages and defined increased dosage as any increase in daily dose in milligrams. When drugs from more than 1 medication class were taken, we considered a dosage increase for any class. For patients who did not have therapy modifications, we assessed the proportion of patients who may have already been receiving maximal therapy. We defined maximal therapy as receiving 3 medications for hypertension or diabetes (including the proportion who were receiving high doses of all 3 medications) or receiving a maximal dose of statin therapy (80 mg of simvastatin or 40 mg of atorvastatin). Combination lipid-lowering therapy was very uncommon. Covariates We examined the relationship between several patient factors and receipt of appropriate care in response to poor control, notably whether physicians responded differently in relation to patients' level of cardiovascular risk as reflected by the presence of several conditions or target organ disease. We defined 3 mutually exclusive categories of cardiovascular risk: history of CAD, other target organ damage, and no history of either condition. We defined previous CAD as any diagnosis of myocardial infarction, angina pectoris, atherosclerotic heart disease, or coronary revascularization recorded during the previous 5 years. We defined target organ damage on the basis of the definitions of the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) (24): previous diagnoses of hypertensive heart disease, congestive heart failure, cerebrovascular or peripheral arterial disease, and nephropathy (defined as renal failure or insufficiency during the previous 5 years or by a most recent serum creatinine level greater than 124 mol/L [>1.4 mg/dL] for women or greater than 133 mol/L [>1.5 mg/dL] for men). Race and ethnicity data were available for 76% of patients from responses to previous member surveys and previous hospital discharges. Statistical Analysis For each condition, we determined th