Outpatient Referral for High Blood Pressure in Emergency Departments

Diagnosing Possible Hypertension When Emergency Department Blood Pressure is HighRichard W. Niska, MD, MPH, FACEPCAPT, US Public Health ServiceIntroductionEmergency physicians refer to primary care specialists for follow-up of conditions identified in the emergency department (ED).

The American College of Emergency Physicians (ACEP) recommends that patients with high blood pressure (BP) be referred for possible hypertension.Decker et al. Clinical policy: critical issues in the evaluation and management of adult patients with asymptomatic hypertension in the ED. Ann Emerg Med. 2006; 47(3):237-49.

Tilman et al. Recognizing asymptomatic elevated BP in ED patients: how good (bad) are we? Am J Emerg Med. 2007; 25(3):313-7.7% of ED patients with asymptomatic high BP were diagnosed, treated, or referred for their BP. No differences were found by age, sex, race or insurance status between patients receiving attention for high BP and not receiving it.

Hypothesis and objectiveHypothesis:High BP readings would trigger a diagnosis of possible hypertension, to facilitate outpatient referral to:establish a formal diagnosis and begin treatmentalter management of poorly controlled hypertensive patients

Objective:To examine factors associated with diagnosing possible hypertension in ED patients with high BPMethodsInclusion criteriaData from the 2003-2008 National Hospital Ambulatory Medical Care Survey ED visit files

All visits by patients 18 years of age or older

BP > 139 mm Hg systolic or > 89 mm Hg diastolicBP missing for 4.5% - not statistically different among yearsExclusion criteria:Diagnoses excluded in ACEP clinical policyAcute hypertensive emergenciesAcute myocardial infarctionIntracranial hemorrhageHypertensive encephalopathyCerebral aneurysmIschemic strokeAortic aneurysmAcute renal failureExclusion criteria:Dispositions precluding outpatient referralAdmission to hospital, intensive care, coronary care or observation unitsTransfer to different hospitalDeath in the EDDead on arrivalLeaving without being seen (before or after medical screening exam)Leaving against medical adviceDependent variableWhether or not hypertension was recorded as a diagnosis at the ED visit

ICD-9 codes:401: essential hypertension402: hypertensive heart disease403: hypertensive chronic kidney disease404: hypertensive heart and chronic kidney disease405: secondary hypertension

Diagnoses could be coded as:ProbableQuestionableRule-outDefinitive diagnoses not so coded

Three diagnoses possible on data abstraction instrumentIndependent variables:JNC-7 stage of BP elevationSystolic BP criteriaSystolic BP 140-159 (stage 1 systolic BP elevation)Systolic BP 160 or greater (stage 2 systolic BP elevation)

Diastolic BP criteriaDiastolic BP 90-99 (stage 1 diastolic BP elevation)Diastolic BP 100 or greater(stage 2 diastolic BP elevation)

Final variable defined hierarchically (either systolic or diastolic BP at higher level)Either systolic or diastole BP at stage 2(stage 2 BP elevation)Then either systolic or diastolic BP at stage 1(stage 1 BP elevation)

Chobanian et al. Seventh report of the Joint National Committee (JNC-7) on Prevention, Detection, Evaluation, and Treatment of High BP. Hypertension. 2003; 42:1206-52.

Independent variables:AgeHigh home BP in patients with 2 hypertensive ED readings was associated with older age. Tanabe et al. Increased BP in the ED: pain, anxiety, or undiagnosed hypertension? Ann Emerg Med. 2008; 51(3):221-9.

Age groups:18-30 years31-45 years46-60 years60 years or older

Cutoffs chosen to include about of sample in each age group (close to median and 25th/75th percentiles)

Avoid potential collinearity with Medicare eligibility in multivariate analysis by not using age 65 as a cutoff

Independent variables:SexMale

FemaleIndependent variables:Race-ethnicityNon-Hispanic whiteNon-Hispanic blackHispanic (white or black)Other (collapsed due to small sample sizes)AsianNative Hawaiian or other Pacific IslanderAmerican Indian or Alaska NativeMultiracial

Independent variables:Primary payment sourceAbility to make phone appointments with primary care providers in Washington, DC, differed by payment source:71 % of hypothetical privately insured patients37% of hypothetical Medicaid patients13% of hypothetical uninsured patientsBlanchard et al. Access to appointments based on insurance status in Washington, D.C. J Health Care Poor Underserved. 2008; 19(3):687-96.

Ability to make phone appointments with clinics for urgent ED follow-up in 9 US cities differed by payment source:Two thirds of research assistants claiming private insurance No difference between privately insured and those offering cash payment in full34% of research assistants claiming Medicaid25% of research assistants claiming being uninsuredAsplin BR, Rhodes KV, Levy H, et al. Insurance status and access to urgent ambulatory care follow-up appointments. JAMA. 2005; 294(10):1248-54.

Primary payment source categories:Private insuranceMedicareMedicaidWorkers compensationNo insurance (self-pay, no charge, charity)OtherUnknownIndependent variables:Survey year2003-2006 Baseline period before publication of ACEP policy

2007

2008Independent variables:Pain severityTanabe et al. also found that:High ED BP was slightly correlated with increased pain scoresMost patients without a history of hypertension who had high BP in ED also had high home BPs.

Pain severity categories:No painMildModerateSevereUnknownIndependent variables:Metropolitan statistical areaMetropolitan (urban)

Non-metropolitan (rural)Statistical MethodsBivariate analysisAssociations between dependent variable and all independent variables

Chi-squares in SUDAAN 9.1 PROC CROSSTABAlpha < 0.05Multivariate analysisLogistic regression model to determine significant predictors of diagnosing possible hypertension

All independent variables included in initial model

Stepwise backward elimination according to highest Wald p-value till all p-values less than 0.05

Odds ratios (OR) with 95% confidence intervals (CI)ResultsAnalysis of adults with high BPNumber of adult ED visits in 2003-2008 at which BP was high:50,444 unweighted visitsRepresents weighted national estimate of about 167 million visits

5.5% diagnosed with possible hypertension

Similar to Tillman (2007): 7% diagnosed, treated or referred

Bivariate analysisSignificant associations (all p