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

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Diagnosing possible hypertension when emergency department blood pressure is high

Diagnosing Possible Hypertension When Emergency Department Blood Pressure is High

Richard W. Niska, MD, MPH, FACEP

CAPT, US Public Health Service


Introduction
Introduction Blood Pressure is High

  • Emergency 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 objective
Hypothesis and objective Blood Pressure is High

  • Hypothesis:

    • High BP readings would trigger a diagnosis of possible hypertension, to facilitate outpatient referral to:

      • establish a formal diagnosis and begin treatment

      • alter management of poorly controlled hypertensive patients

  • Objective:

    • To examine factors associated with diagnosing possible hypertension in ED patients with high BP


Methods Blood Pressure is High


Inclusion criteria
Inclusion criteria Blood Pressure is High

  • Data 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 diastolic

    • BP missing for 4.5% - not statistically different among years


Exclusion criteria diagnoses excluded in acep clinical policy
Exclusion criteria: Blood Pressure is HighDiagnoses excluded in ACEP clinical policy

  • Acute hypertensive emergencies

  • Acute myocardial infarction

  • Intracranial hemorrhage

  • Hypertensive encephalopathy

  • Cerebral aneurysm

  • Ischemic stroke

  • Aortic aneurysm

  • Acute renal failure


Exclusion criteria dispositions precluding outpatient referral
Exclusion criteria: Blood Pressure is HighDispositions precluding outpatient referral

  • Admission to hospital, intensive care, coronary care or observation units

  • Transfer to different hospital

  • Death in the ED

  • Dead on arrival

  • Leaving without being seen (before or after medical screening exam)

  • Leaving against medical advice


Dependent variable
Dependent variable Blood Pressure is High

  • Whether or not hypertension was recorded as a diagnosis at the ED visit

  • ICD-9 codes:

  • 401: essential hypertension

  • 402: hypertensive heart disease

  • 403: hypertensive chronic kidney disease

  • 404: hypertensive heart and chronic kidney disease

  • 405: secondary hypertension

  • Diagnoses could be coded as:

    • Probable

    • Questionable

    • Rule-out

    • Definitive diagnoses not so coded

  • Three diagnoses possible on data abstraction instrument


Independent variables jnc 7 stage of bp elevation
Independent variables: Blood Pressure is HighJNC-7 stage of BP elevation

  • Systolic BP criteria

    • Systolic BP 140-159 (stage 1 systolic BP elevation)

    • Systolic BP 160 or greater (stage 2 systolic BP elevation)

  • Diastolic BP criteria

    • Diastolic 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 age
Independent variables: Blood Pressure is HighAge

  • High 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 years

    • 31-45 years

    • 46-60 years

    • 60 years or older

  • Cutoffs chosen to include about ¼ 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 sex
Independent variables: Blood Pressure is HighSex

  • Male

  • Female


Independent variables race ethnicity
Independent variables: Blood Pressure is HighRace-ethnicity

  • Non-Hispanic white

  • Non-Hispanic black

  • Hispanic (white or black)

  • Other (collapsed due to small sample sizes)

    • Asian

    • Native Hawaiian or other Pacific Islander

    • American Indian or Alaska Native

    • Multiracial


Independent variables primary payment source
Independent variables: Blood Pressure is HighPrimary payment source

  • Ability to make phone appointments with primary care providers in Washington, DC, differed by payment source:

    • 71 % of hypothetical privately insured patients

    • 37% of hypothetical Medicaid patients

    • 13% of hypothetical uninsured patients

      Blanchard 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 full

    • 34% of research assistants claiming Medicaid

    • 25% of research assistants claiming being uninsured

      Asplin 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 insurance

    • Medicare

    • Medicaid

    • Worker’s compensation

    • No insurance (self-pay, no charge, charity)

    • Other

    • Unknown


Independent variables survey year
Independent variables: Blood Pressure is HighSurvey year

  • 2003-2006

    • Baseline period before publication of ACEP policy

  • 2007

  • 2008


Independent variables pain severity
Independent variables: Blood Pressure is HighPain severity

  • Tanabe et al. also found that:

    • High ED BP was slightly correlated with increased pain scores

    • Most patients without a history of hypertension who had high BP in ED also had high home BPs.

  • Pain severity categories:

    • No pain

    • Mild

    • Moderate

    • Severe

    • Unknown


Independent variables metropolitan statistical area
Independent variables: Blood Pressure is HighMetropolitan statistical area

  • Metropolitan (urban)

  • Non-metropolitan (rural)


Statistical Methods Blood Pressure is High


Bivariate analysis
Bivariate analysis Blood Pressure is High

  • Associations between dependent variable and all independent variables

  • Chi-squares in SUDAAN 9.1

    • PROC CROSSTAB

    • Alpha < 0.05


Multivariate analysis
Multivariate analysis Blood Pressure is High

  • Logistic 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)


Results Blood Pressure is High


Analysis of adults with high bp
Analysis of adults with high BP Blood Pressure is High

  • Number of adult ED visits in 2003-2008 at which BP was high:

    • 50,444 unweighted visits

    • Represents weighted national estimate of about 167 million visits

  • 5.5% diagnosed with possible hypertension

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


Bivariate analysis1
Bivariate analysis Blood Pressure is High

  • Significant associations (all p<0.01)

    • BP elevation stage

    • Age

    • Sex

    • Race-ethnicity

    • Pain severity

    • Payment source

  • Payment source:

    • Dropped out of multivariate model after adjustment for all other covariates

    • Replicates Tillman (2007): no differences by insurance status in addressing high BP


Hypertension diagnosis more likely increasing stage of high bp
Hypertension diagnosis more likely: Blood Pressure is HighIncreasing stage of high BP

  • Stage 2

    • OR 4.96 (95% CI 4.31–5.71)

    • P<0.01

  • Stage 1

    • Reference group


Hypertension diagnosis more likely increasing age
Hypertension diagnosis more likely: Blood Pressure is HighIncreasing age

  • 18-30 years

    • Reference group

  • 31-45 years

    • OR 1.77 (95% CI 1.40–2.23)

    • P<0.01

  • 46-60 years

    • OR 2.52 (95% CI 2.00–3.16)

    • P<0.01

  • Over 60 years

    • OR 2.53 (95% CI 1.98–3.25)

    • P<0.01


Hypertension diagnosis more likely female sex
Hypertension diagnosis more likely: Blood Pressure is HighFemale sex

  • Female

    • OR 1.17 (95% CI 1.06–1.28)

    • P<0.01

  • Male

    • Reference group


Hypertension diagnosis more likely minority ethnic groups
Hypertension diagnosis more likely: Blood Pressure is HighMinority ethnic groups

  • Non-Hispanic white

    • Reference group

  • Non-Hispanic black

    • OR 2.39(95% CI 2.05–2.78)

    • P<0.01

  • Hispanic (white or black)

    • OR 1.52 (95% CI 1.25–1.83)

    • P<0.01

  • Other

    • OR 1.61 (95% CI 1.24–2.09)

    • P<0.01


Hypertension diagnosis more likely decreasing pain level
Hypertension diagnosis more likely: Blood Pressure is HighDecreasing pain level

  • No pain

    • OR 2.18 (95% CI 1.86–2.55)

    • P<0.01

  • Mild pain

    • OR 1.27 (95% CI 1.06–1.52)

    • P=0.01

  • Moderate pain

    • OR 1.13 (95% CI 0.96–1.32)

    • Not significant

  • Severe pain

    • Reference group

  • Unknown

    • OR 1.45 (95% CI 1.21–1.75)

    • P<0.01

    • Does this category really mean “no pain?”

    • Less likely to record pain when not an issue?


Limitations Blood Pressure is High


  • Evaluating the effect of a clinical policy on referral would be more precisely done by studying referral directly.

  • But survey referral variables not tied to a specific diagnosis.

  • Results should be interpreted with caution since we do not know whether diagnosing hypertension would actually lead to referral.


  • Survey allows abstraction of up to 3 diagnoses be more precisely done by studying referral directly.

  • Possible that hypertension diagnosis not abstracted if there were 3 or more higher-priority diagnoses

  • However, we found blank entries in:

    • 84.8% of 3rd diagnosis fields

    • 56.8% of 2nd diagnosis fields

    • 0.6% of 1st diagnosis fields

    • These blank fields were available to abstract a hypertension diagnosis if one existed in the medical record.


Conclusions be more precisely done by studying referral directly.


Survey year
Survey year be more precisely done by studying referral directly.

  • No improvement in diagnosing possible hypertension in 2007 or 2008 compared to the years before, during, and immediately after the clinical policy on referral was published.

  • Lehrmann et al. Knowledge translation of the ACEP clinical policy on hypertension. Acad Emerg Med. 2007; 14(11):1090-6.

    • Studied referral rates of patients with high BP by emergency physicians at 2 centers before and after dissemination of the ACEP clinical guideline

      • 13% referred before policy dissemination

      • 7% afterwards

  • More research needed for later years, since this policy is on the 2009 Lifelong Learning & Self Assessment reading list of the American Board of Emergency Medicine

    • Passing tests on readings are required to maintain emergency medicine certification

    • Improvement expected as more ED physicians become sensitized to the need for referral


Stage of bp elevation
Stage of BP elevation be more precisely done by studying referral directly.

  • Five-fold increased likelihood of possible hypertension diagnosis when BP is stage 2 compared to stage 1

  • Baumann et al. Provider self-report and practice: reassessment and referral of ED patients with elevated BP. Am J Hypertens. 2009; 22(6):604-10.

    • Mean threshold at which providers would refer patients was 150/93

    • Mean BP of adult ED patients who actually received a referral for outpatient management was 170/97.


Age be more precisely done by studying referral directly.

  • All groups older than 30 years more likely to be diagnosed with hypertension than those 18-30 years old

    • Different from Tillman (2007): no difference by age in addressing high BP.

  • But younger patients might stand to benefit from early management of their hypertension, even though it is less prevalent in that age group.

  • Ostchega et al. Hypertension awareness, treatment, and control – continued disparities in adults: US, 2005-2006. NCHS data brief no. 3. Hyattsville, MD: National Center for Health Statistics. 2008.

    • Significant differences in the prevalence of hypertension among adults:

      • age 18-39 years (7%)

      • age 40-59 (about 1/3)

      • age 60 and older (67 %)

    • 5% age 18-59 years and 12% age 60 and older had hypertension and had never been told by a health care provider that they had it.

  • Not referring ED patients of any age with a high BP reading may represent a significant missed opportunity in controlling hypertension.


Race ethnicity
Race-ethnicity be more precisely done by studying referral directly.

  • In contrast to a priori expectation that disparities would be demonstrated for minority patients, our findings strongly predicted:

    • increased likelihood of diagnosis for non-Hispanic black & Hispanic (p<0.01)

    • less strongly predictive but still significant (p=0.02) for other ethnicities

    • Different from Tillman (2007): no differences by race in addressing high BP

  • Ostchega et al. found that U.S. prevalence of hypertension was:

    • highest among non-Hispanic black persons (41 percent)

    • lower in Mexican-American persons (22 percent)

    • Both groups significantly different from non-Hispanic white (28%)

  • More research is needed on the impact of race-ethnicity on diagnostic sensitivity, especially if disparities do not apply universally to all minority groups


Pain be more precisely done by studying referral directly.

  • Controversial tendency to view high BP as a manifestation of pain, rather than indicative of possible hypertension

  • The finding that possible hypertension is more often diagnosed when pain is absent or mild is consistent with this belief.

  • Svenson & Repplinger. Hypertension in the ED: still an unrecognized problem. Am J Emerg Med. 2008; 26(8):913-7.

    • No correlation between high BP and pain scores in either adults or children

    • Follow-up for high BP only recommended for 4% of patients in their ED

  • Fleming et al. Detection of hypertension in the ED. Emerg Med J. 2005; 22(9):636-40.

    • No correlation between pain scores and mean BP in their ED

    • 62% of subjects with pain scores >5 of 10 still had high BPs on follow-up when pain scores no longer elevated

  • More research is needed to determine whether high BP readings are a manifestation of underlying hypertension, regardless of pain severity.


Sex be more precisely done by studying referral directly.

  • Being female was a predictor of receiving a diagnosis of possible hypertension:

    • Association not as strong as other factors in the model

    • Different from Tilman (2007): no differences by sex in addressing high BP

  • More research needed to replicate findings


What does it mean
What does it mean? be more precisely done by studying referral directly.

  • Increased referral of patients with high BPs could have significant public health benefits in the prevention of cardiovascular complications from chronic hypertension.

  • Increased vigilance to diagnose and refer patients with high BP readings is indicated for:

    • Younger patients

    • Men

    • Patients in moderate to severe pain


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