Table 2.

Performance of the resistant hypertension (RHTN) computable phenotype algorithms

CP	Presumptive RHTN, n	Subset of charts reviewed, n	Confirmed RHTN, n (%)	PPV (95% CI)
Algorithm 1*	27,978	25	21 (84.0)	84.0 (63.9–95.5)
Algorithm 2**	25,933	37	33 (89.2)	89.2 (74.6–97.0)
Final Algorithm***	24,926	113	112 (99.1)	99.1 (95.2–99.9)

RHTN: Resistant Hypertension, PPV: Positive predictive value, CI: confidence interval

^*Algorithm 1: RHTN algorithm based on the 2008 AHA statement on resistant hypertension and the eMERGE RHTN algorithm (RHTN)

^**Algorithm 2: Algorithm 1 + CPT codes algorithm added CPT codes to identify patients with routine outpatient encounters, and only use blood pressure readings from routine outpatient encounters (RHTN + CPT codes)

^***Final Algorithm: Algorithm 2 + drug counting algorithm added additional consideration for patients switching between single pill and combination pill preparations of the same antihypertensive drug class (RHTN + CPT codes + drug counting)