Study Overview
Objective. To identify the prevalence and characteristics of patients identified with high blood pressure (BP) in nonprimary care compared with primary care visits.
Design. Longitudinal population-based study.
Setting and participants . This study was conducted at Kaiser Permanente Southern California (KPSC) after implementation of a system-wide change to improve hypertension care, which included comprehensive decision support tools embedded in the EHR system, including BP measurement flag alerts. Patient eligible for the study were normotensive members (BP < 140/90 mm Hg), older than 18 years, and enrolled in a KPSC health plan for at least 12 months on January of 2009. A gap of < 3 months in health care coverage in the year prior was allowed. Excluded were patients with a history of elevated BP during an outpatient visit, an inpatient or outpatient diagnosis code for hypertension, prescription for any antihypertensive medication within 24 months prior to 1 January 2009, missing BP information or whose only BP measurements were from a visit indicating fever or in preparation for a surgery or pain management. Pregnant patients, patients with missing sex information, and missing visit specialty information were also excluded. The study period was from January 2009 to March 2011.
Measurement. BP was measured routinely at the beginning of almost every primary and nonprimary outpatient visit. Nurses and medical assistants were trained according to a standard KPSC protocol using automated sphygmomanometer digital devices. According to the study protocol, in cases in which BP was elevated (≥ 140/90 mm Hg), a second measurement was obtained. At KPSC, all staff members including those in primary and nonprimary care are certified in BP measurement during their initial staff orientation and recertified annually.
Main outcome measure . An initial BP ≥ 140/90 mm Hg during a primary or nonprimary care outpatient visit.
Results. The mean ages of patients at baseline and at end of follow-up for the primary outcome were 39.7 (SD, 13.9) and 41.5 (SD, 14.0) years, respectively. The total cohort ( n = 1,075,522) was nearly equally representative of both men (48.6%) and women (51.4%). The majority of the patients (91.7%) were younger than 60 years. A large proportion of the cohort belonged to racial/ethnic minorities with 33.1% Hispanic, 6.5% black, and 8.4% Asian/Pacific Islander.
The total cohort had 4,903,200 office visits, of which 3,996,190 were primary care visits, 901,275 nonprimary care visits, and 5735 visits of unknown specialty. During a mean follow-up of 1.6 years (SD, 0.8) 111,996 patients had a BP measurement ≥ 140/90 mm Hg. Of these, 92,577 (82.7%) were measured during primary care visits and 19,419 (17.3%) during nonprimary care visits. Of 15,356 patients with confirmed high BP, 12,587 (82%) were measured during primary care visits and 2769 (18.0%) patients during nonprimary care visits. Patients with a BP ≥ 140/90 mm Hg measured during nonprimary care visits were older, more likely to be male and non-Hispanic white, less likely to be obese, but more likely to smoke or have a Framingham risk score ≥ 20%. Ophthalmology/optometry, neurology, and dermatology were the main specialties to identify a first BP ≥ 140/90 mm Hg.
The follow-up after a first elevated BP was marginally higher in patients identified in nonprimary care than in primary care. Among patients with a first BP ≥ 140/90 mm Hg measured during a primary care visit, 60.6% had a follow-up BP within 3 months of the first high BP, 22.9% after 3 months or more, and 16.5% did not have a follow-up BP. Among individuals with a first BP ≥ 140/90 mm Hg measured during a nonprimary care visit, 64.7% had a follow-up BP within 3 months of the first high BP, 22.6% after 3 months or more, and 12.7% did not have a follow-up BP measurement.
The proportion of false-positives, defined as individuals with an initial BP ≥ 140/90 mm Hg who had a follow-up visit with a normal BP within 3 months, was the same for patients identified in primary and nonprimary care. False-positives were most frequent in individuals identified during visits in other specialty care, rheuma-tology, and neurology fields.
Conclusion. Expanding screening for hypertension to nonprimary care settings may improve the detection of hypertension and may contribute to better hypertension control. However, an effective system to ensure appropriate follow-up if high BP is detected is needed. Elderly, non-Hispanic, white male patients and those with very high BP are more likely to benefit from this screening.
Commentary
Hypertension is a common and costly health problem [1]. BP screening can identify adults with hypertension, who are at increased risk of cardiovascular and other diseases. Effective treatments are available to control high BP and reduce associated morbidity and mortality [2], but the first step is to identify patients with this largely asymptomatic disorder.
BP measurement is standard practice in primary care. However, many people do not regularly see a primary care clinician. In this study, researchers aimed to identify the prevalence and characteristics of patients identified with high BP in nonprimary care compared with primary care visits in a large integrated health care system that had implemented a system-level, multifaceted quality improvement program to improve hypertension care. Of the patients who were found to have high BP, 83% were diagnosed in a primary care setting and 17% in a specialty care setting, and the number of false-positive results were comparable.
In general, the study was well conducted and a strength of the study was the large sample size. Limitations included the fact that the study was conducted as part of a quality improvement project in an integrated health system, and there were no control clinics.
The authors noted that a high BP reading requires adequate follow-up, and nonprimary care detected elevated BP patients had lower follow-up rates. Also, some specialties had higher false-positive rates. Quality of measurement can be maximized with regular staff training.
Applications for Clinical Practice
Expanding routine screening for hypertension to non-primary care can potentially improve rates of detection, capturing patients who might otherwise have been missed. An effective system to ensure appropriate follow-up attention if high BP is detected is essential, and it is important that staff be well trained in using standard technique to minimize false-positives, which could lead to unnecessary resource use.
—Paloma Cesar de Sales, BN, RN, MS