Office Visits

Eligible participants were assigned to a systolic blood-pressure target of either less than 140 mm Hg (the standard-treatment group) or less than 120 mm Hg (the intensive-treatment group). Randomization was stratified according to clinical site. Participants and study personnel were aware of the study-group assignments, but outcome adjudicators were not.
After the participants underwent randomization, their baseline antihypertensive regimens were adjusted on the basis of the study-group assignment. The treatment algorithms were similar to those used in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial.^{22 (link)} These algorithms and our formulary are listed in Figures S1 and S2 and Table S1 in the Supplementary Appendix. All major classes of antihypertensive agents were included in the formulary and were provided at no cost to the participants. SPRINT investigators could also prescribe other antihypertensive medications (not provided by the study). The protocol encouraged, but did not mandate, the use of drug classes with the strongest evidence for reduction in cardiovascular outcomes, including thiazide-type diuretics (encouraged as the first-line agent), loop diuretics (for participants with advanced chronic kidney disease), and beta-adrenergic blockers (for those with coronary artery disease).^{5 (link),27 (link)} Chlorthalidone was encouraged as the primary thiazide-type diuretic, and amlodipine as the preferred calcium-channel blocker.^{28 (link),29 (link)} Azilsartan and azilsartan combined with chlorthalidone were donated by Takeda Pharmaceuticals International and Arbor Pharmaceuticals; neither company had any other role in the study.
Participants were seen monthly for the first 3 months and every 3 months thereafter. Medications for participants in the intensive-treatment group were adjusted on a monthly basis to target a systolic blood pressure of less than 120 mm Hg. For participants in the standard-treatment group, medications were adjusted to target a systolic blood pressure of 135 to 139 mm Hg, and the dose was reduced if systolic blood pressure was less than 130 mm Hg on a single visit or less than 135 mm Hg on two consecutive visits. Dose adjustment was based on a mean of three blood-pressure measurements at an office visit while the patient was seated and after 5 minutes of quiet rest; the measurements were made with the use of an automated measurement system (Model 907, Omron Healthcare). Lifestyle modification was encouraged as part of the management strategy. Retention in the study and adherence to treatment were monitored prospectively and routinely throughout the trial.^{26 (link)}

For measuring hospital inpatient utilization, we used DRG-based quantity measures that are designed to reflect “true” medical inputs. (DRG prices are set to reflect the average of patients' hospital-borne costs within a large sample of hospitals.) We included outlier payments, which constitute 3.7 percent of total payments to short-stay hospitals, in our measure of utilization because they represent real resources spent for patients with unusually high health care costs.
For payments to physicians under the Medicare Part B (physician services) program, we relied primarily on relative value units, which Medicare uses as a measure of the amount of time spent on an office visit, for example. In practice, Medicare reimburses physicians in New York more for an office visit than for an identical office visit in Wisconsin by paying more per relative value unit. Our method “undoes” this differential by recreating Part B spending using the same dollar payment per relative value unit whether the doctor is in Wisconsin or New York. Thus, if Part B spending is higher in New York, it's because more services are provided, and not because prices are higher.
Other Medicare spending categories were calculated to measure, indirectly, the actual service provided to the patient. These adjustments relied in turn on the CMS regional wage index as the primary mechanism to adjust Medicare expenditures. The wage index is particularly useful when the price-adjustment mechanism used by Medicare to reimburse providers is too complex to unravel or requires additional data sets (such as nursing home risk-adjustment assessments). This index is the primary means to adjust expenditures for the variety of Medicare spending components exclusive of Part A inpatient and Part B physician payments.
For Medicare outpatient payments, only 60 percent of the base payment is eligible for adjustment by the local wage index. Medicare assumes that 60 percent of expenses represent local purchases (and hence local prices) for employees, rents, and other input costs. The remaining 40 percent of Medicare outpatient payments are assumed to not require local price adjustment because they are bought on a national market.10
A similar logic was used for other categories of Medicare expenditures, although we assumed a 75/25 mix—a rough average among the different categories of expenditures such as nursing homes—rather than the 60/40 mix described above.11 –13 The adjustment factors for these smaller components of overall Medicare spending may be imperfect. But these imperfections have little impact on our overall estimates of Medicare spending because they are small relative to inpatient and physician charges that rely on DRGs and RVUs, respectively.