Lindsy R. Moore, PharmD

To evaluate the health system cost of a home blood pressure monitoring (HBPM) program versus usual care in an integrated healthcare system.

This cost-effectiveness analysis was based upon a previously completed randomized controlled trial of 348 hypertensive patients, in which mean systolic blood pressure (BP) was lowered 21 versus 8 mm Hg in the HBPM and usual care groups, respectively, and BP control was achieved in 54% versus 35% of patients (

This analysis compared direct costs from the health plan perspective, including clinic visits, e-mail and telephone encounters, laboratory tests, medications, hospitalizations, and emergency department visits between the 2 groups. Primary outcomes were the incremental hypertension care-related cost of HBPM per mm Hg lowering of systolic BP per patient, per additional BP controlled, and per life-year gained.

Median hypertension-related cost per patient over 6 months was $455 in the HBPM group and $179 for usual care (P <.001). This increase was attributable to additional e-mail and telephone encounters, greater antihypertensive medication use, additional laboratory monitoring, and the BP monitor. Median total cost per patient was $1530 and $1283 for the HBPM and usual care groups, respectively (

 = .034). The HBPM program increased hypertension-related expenditures by $20.50 per mm Hg lowering of systolic BP, $1331 per additional patient achieving BP control at 6 months, and $3330 per life-year gained.

The HBPM program requires investment in outpatient encounters, medications, and laboratory monitoring, but produces significantly improved BP control.

This study highlights the cost-effective manner in which home-monitoring technology plus clinical pharmacy specialist involvement improves blood pressure (BP) control.

		Patients in the Home Blood Pressure Monitoring (HBPM) program had more overall telephone and email encounters with a pharmacist, but the same number of office visits with a pharmacist, and utilized more antihypertensive medications and laboratory monitoring compared with patients managed through usual care.

		The incremental 6-month cost of this intervention was $20.50 per mm Hg of systolic BP lowered, $1331 per additional BP controlled, and $3330 per life-year gained compared with usual care.

		The incremental costs of this intervention compare favorably with other interventions, largely because the HBPM program was more effective than usual care.

Nearly $51 billion in direct and indirect costs related to hypertension were spent in the United States in 2009, with much of it attributable to the healthrelated consequences of hypertension.

 One in 3 adults in the United States has hypertension, and about half of those have uncontrolled blood pressure (BP), putting them at increased risk for acute myocardial infarction, stroke, renal disease, and congestive heart failure.

 Lowering BP has been shown to reduce the occurrence of these events.

Despite effective therapeutic interventions to control BP, at least a quarter of patients with uncontrolled hypertension receive no pharmacologic treatment. Novel care delivery models using home BP monitoring have demonstrated improved BP control.

 Demonstrating the benefits, costs, and cost effectiveness of such programs will help clinicians and policy makers to decide whether to invest in these programs.

Investigators at Kaiser Permanente Colorado (KPCO) conducted a randomized, controlled trial to evaluate the effectiveness of a home BP monitoring (HBPM) intervention that used the American Heart Association Heart360 Web interface (

) to send home BP readings to a clinical pharmacy specialist who managed the patient’s medication therapy via phone or e-mail communication. The purpose of this study was to determine the cost-effectiveness of the HBPM program compared with usual care.

The study was conducted at KPCO, a group-model, closed-panel, nonprofit managed care organization that cares for more than 500,000 members in the Denver-Boulder metropolitan area. Outpatient medical services are provided at 18 primary care clinics spread geographically across the metropolitan area, 10 of which participated in the present study. Each clinic is staffed with 1 or more clinical pharmacy specialists who assist primary care providers with drug therapy management. With regard to hypertension management, clinical pharmacy specialists work under preapproved collaborative drug therapy management protocols that permit them to initiate or change antihypertensive medications, adjust medication doses, and order laboratory tests related to medication monitoring. KPCO clinicians use a commercially available EpicCare electronic health record (EHR) as part of routine care delivery. The KPCO EHR has a feature called My Chart which allows patients and their providers to communicate electronically through a password-protected website.

The study was approved by the KPCO Institutional Review Board.

The HBPM study has been described in detail elsewhere. 8 This was a randomized, controlled study of 348 patients with uncontrolled hypertension randomly assigned to the HBPM program or usual care. Patients in the HBPM group were provided with and trained to use a home BP monitor (Omron HEM-790IT monitor), and they were guided in establishing a Heart360 account and in how to automatically upload BP measurements from their monitor to their Heart360 account. Patients in the HBPM group also met with a clinical pharmacy specialist, who reviewed their current BP medication regimen, provided counseling on lifestyle changes, and adjusted or changed antihypertensive medications, as needed. Patients in the usual care group were instructed to follow up with their primary care physician for BP care. Patients in both groups returned at 6 months for an in-clinic BP measurement. Blood pressure goal was <140/90 mm Hg for all patients, except for those with diabetes mellitus or chronic kidney disease for whom the goal was <130/80 mm Hg. At 6 months, 54% of patients in the HBPM group attained their BP goal, compared with 35% in the usual-care group (

 <.001). The HBPM group lowered their systolic blood pressure (SBP) by an average of 21 mm Hg compared with 8 mm Hg in the usual care group (

The economic analysis was conducted from the health plan perspective over the 6-month study period. Cost inputs included costs of the blood pressure cuff, clinic visits, e-mail and telephone encounters, laboratory tests, medications, hospitalizations, and emergency department (ED) visits. Indirect costs (eg, the administrative costs necessary for day-to-day operations) were not included as they were not expected to differ between the groups.

Healthcare utilization data were collected for 6 months prior to and after study enrollment using administrative databases maintained by KPCO. Data included all outpatient encounters (office visits, telephone contacts, e-mails), laboratory and radiology tests, prescriptions, ambulatory surgery, ED visits, and hospital admissions both within the KPCO system as well as claims for care that occurred outside KPCO. Costs were classified as hypertension-related if the primary 

International Classification of Diseases, Ninth Revision, Clinical Modification

 code associated with each expenditure was hypertension (401.9); hospitalizations, clinic encounters, and ED visits were reviewed manually to verify accurate categorization. Current procedural terminology codes were used to assign costs according to a fee schedule derived from the 2009 national Medicare fee schedule.

Costs for professional claims were based on billed amounts. Prescriptions billed through insurance were collected during the same time frame, and costs were determined using discounted average wholesale price to approximate Medicare pricing, with the addition of an $8 dispensing fee.

Costs for the initial clinic visit, telephone encounters with a clinical pharmacy specialist, and all e-mail encounters were estimated by multiplying the time spent by each provider type by the hourly wage. Provider compensation rates were taken from the United States Census Bureau wages and compensation 2009 data plus 29.2% to account for benefits.

The following hourly rates were used: pharmacist, $74.14; medical assistant, $19.39; registered nurse, $44.09; and physician, $99.72. The initial clinic visits differed in that the HBPM group required an additional 20 minutes of medical assistant time for training on the home BP monitor, setting up a Heart360 account, and downloading BP readings to the website, plus 20 minutes with a clinical pharmacy specialist to review antihypertensive medications and make any necessary dose adjustments. Based on a survey of the clinical pharmacy specialists participating in the study, pharmacist time was estimated at 10 minutes for each telephone follow-up encounter. E-mails from any provider were estimated at 6 minutes per e-mail encounter. All costs have been adjusted to reflect 2013 dollars using the Consumer Price Index rates for medical costs.16 The selected home BP monitor or a similar model can be purchased for approximately $60.

Direct costs were grouped into the following categories: outpatient encounters (including in-person clinic visits, telephone calls, and e-mail exchanges); outpatient laboratory; pharmacy outpatient; and all other costs (ambulatory surgery, ED, hospitalizations, and outpatient radiology). Total healthcare costs for 6 months prior to enrollment were compared between groups to assess for baseline differences in costs and to adjust for such differences (if present) during the study period. Total and hypertension-related costs during the 6-month study period were calculated to demonstrate the relationship between hypertension-related and total healthcare costs and to capture any unintended increases in healthcare utilization (eg, due to adverse events) related to the study. Three incremental cost-effectiveness ratios (ICERs) were calculated: cost per mm Hg lowering of SBP per patient, cost per controlled BP achieved, and cost per life-year gained. To determine the cost of an additional 1 mm Hg lowering of SBP in a patient, the mean difference in 6-month costs for hypertension care was divided by the mean SBP change in each group. To determine the cost of 1 patient achieving BP control, the mean difference in 6-month hypertension-related costs was divided by the difference in the number of patients achieving control in each group.

Cost per life-year gained was determined by first calculating the discounted life expectancy (DLE) for each patient at baseline and after the intervention using the formula:

=1.5% is the discount rate for life years,

is the current age of the patient in years, and 

 denotes the probability of surviving until age 

 denotes the 1-year risk of death for a patient of age s with the same gender and BP control level as the patient. (The symbol Π denotes the product operator; for example 

 ). The mortality rates were estimated from life expectancy data based on age, gender, and BP control level.18 The mortality rate for a patient of age s years was calculated by the formula:

 is the life expectancy of a patient of age s of the same gender and BP control level; this was determined by linear interpolation or extrapolation from Tables 3, 

 The mortality rate formula was derived by assuming that deaths occur at the end of each year so that:

We calculated the incremental hypertension care costs of the intervention for year 1 of the program plus subsequent years of follow-up. Total hypertension care cost in each group for year 1 was calculated by first estimating the increased cost of antihypertensive medications for the entire year for each patient. To account for expected follow-up needs in the second 6-month period, the costs for non—study-related outpatient encounters in the first 6 months was doubled and an additional e-mail encounter was added for intervention patients. Additional laboratory costs were not added for the second 6-month period because most antihypertensive medications require annual monitoring. To determine the incremental hypertension care cost for each intervention patient in year 1, the mean cost of a usual-care patient was subtracted from the actual cost for each intervention patient. Incremental cost for subsequent years was calculated as the average difference in costs for antihypertensive medication plus laboratory monitoring between groups plus the cost of 3 e-mail encounters in the intervention group.

The discounted cost of intervention for each patient in the intervention group was calculated by the formula:

where rc = 3% is the discount rate for costs,

 is the incremental hypertension care cost for intervention patients in year 1 as described above, and 

 is the incremental cost for each subsequent year. Subset analyses were performed on the group of patients with diabetes mellitus to calculate the incremental cost-effectiveness ratios for this high-risk group.

Cost comparisons between each group were reported as median and interquartile range values as cost data were not normally distributed. Wilcoxon rank sum was used to determine the significance of the between-group differences in cost. Level of significance was set at an α of 0.05. All statistical analyses were performed using SAS version 9.2 (SAS Institute, Carey, North Carolina).

The average age of the 348 study participants was 60 years; about 60% were male (

). Almost half of the participants had either diabetes mellitus or chronic kidney disease (Table 1).

Compared with patients in the usual care group, patients in the HBPM group had significantly more e-mail (median 5 vs 1, 

 <.001) encounters during the 6-month study period. There were no statistically significant differences between the 2 groups in the number of office visits, ED visits, or hospitalizations over the 6-month study period (

There were no statistically significant differences in total costs for the intervention and usual care groups in the 6-month pre-enrollment period (

 = .828 for total costs). Median total healthcare costs per patient during the 6-month study period were higher in the HBPM group ($1590) than in the usual care group ($1283; 

). This difference was largely driven by higher outpatient encounter costs ($481 vs $381, 

 = .006) and higher medication costs ($622 vs $475, 

 = .034) for HBPM and usual care groups, respectively.

When only considering hypertension-related costs, all major cost categories were higher in the HBPM group (median hypertension-related care cost of $455 per patient) compared with usual care (median cost $179; 

 <.001, Table 3). The incremental hypertension-related cost per additional mm Hg reduction in SBP was $20.50. The incremental hypertension-related cost per patient who achieved BP control was $1331 (

Articles

A technology-based, pharmacist-run home blood pressure monitoring program improves health outcomes by investing $20.50 per mm Hg systolic blood pressure lowered and $3300 per life-year gained.

Lindsy R. Moore, PharmD

Articles

Cost-effectiveness Evaluation of a Home Blood Pressure Monitoring Program