During each clinic visit, BP was measured by nursing staff using the same validated oscillometric device (Welch Allyn, Skaneateles Falls, NY) after the patient had been resting quietly for 5 minutes as recommended by guidelines. BP measurement during a single visit was repeated three times separated by 1 minute and the values averaged. Serum levels of antihypertensive medications were assessed as part of our routine standard of care for new referral patients with apparent TRH since 2009. Screening for nonadherence was conducted at Compliance With Clinical Laboratory Improvement Act–certified laboratories as previously described. Patients with serum levels of one or more prescribed antihypertensive medications below the minimal detection limit were considered to be nonadherent. Medication nonadherence ratio was calculated as the number of undetectable antihypertensive medications divided by the total number of antihypertensive medications tested.