case scenario : hypertension

Case Information

CC/HPI: A 37 year old white male with an otherwise unremarkable past medical history presents to his doctor for routine physical. He presents with no complaints.
Past Medical History: None
Medication History: None
Vaccination History: up to date.
Adherence/Medication Use Behaviors: Patient was on time to doctor's appointment.
Drug Allergies/Adverse Effects: NKDA
Pharmacy/Medical Payment: Employer Insurance
Medications Administered by: Self
Family Medical History:
Father/Mother: unremarkable
Siblings: unremarkable
Children: none
Other: none

Social History:
Residence: single apartment
Occupation: office worker
Smoking: none
Diet: fast food
EtOH: none
Education: Masters degree
Illicit Drugs: none
Family/Social Environment: lives alone

Symptom Analysis:
Head, Eyes, Neck, Throat: Denies blurriness or change of vision, confusion, speech and cognition disorders.
Heart: Denies chest pain and palpitations.
Lung: Denies shortness of breath.
Gastrointestinal: Denies abnormalities of frequency, color, and consistency of stool. Denies bowel pain or cramping.
Gennitourinal: Denies abnormalities of frequency, color, and consistency of urination.
Musculoskeletal: Denies weakness, cramping, pain or paralysis.
Extremities: Denies numbness, tingling, coldness, or color abnormalities.
Neuro/Psych: Denies anxiety, depression, sleep disorders.

Physical Exam:
Head, Eyes, Neck, Throat: Patient presents with no facial asymmetries or drooping. No abnormal venous pulsations. Fundoscopy not performed.
Heart: S1 and S2 heart sounds present. No murmurs. No S3 or S4 sounds present.
Lung: Lungs clear to auscultation. No wheezing, crackles or ronchi. Percussion produces neither dull or hyperresonant sounds.
Abdominal: Normal active bowel sounds present. Non-tender and non-distended. No bruits over aortic, renal or illiac positions.
Extremities: Bilateral pulses present that are regularly regular rhythm. Hair symmetrically present. No nail clubbing present.
Neuro/Psych: Patient is amiable and cooperative. Responsive to questions and commands.

Vital Signs:
Temp: 98.6 F
Heart Rate (right arm): 74 (regularly regular)
Blood Pressure (right arm, sitting): 152/94
Respiratory Rate: 16 breaths/minute
Height/Weight: 5'11'' 190 lbs (BMI: 26.5)

Discussion

Most will consider this discussion overdone especially in this patient who presents with an unremarkable presentation. However, the thoroughness of our discussion here will set the stage for further cases that have relevant presentations of hypertensive complications. This discussion will first establish a diagnosis followed by rationale for how that diagnosis was derived. Following diagnosis, we will establish a likely prognostic course in this patient if left without intervention. Finally, we will discuss the best interventions to take in this patient to promote the best prognostic outcome.

Diagnosis
With a single first measurement of blood pressure, in this patient, it is not appropriate to jump to a diagnosis of hypertension. Academically, guidelines recommend three separate measurements of an elevated blood pressure (>140/90) within a six month period prior to a hypertension diagnosis[1]. Acquiring patient specific medical and social history is vital in directing a relevant diagnosis. Hypertension is a "silent" disease that presents with no symptoms. However, complications of organ damage secondary to hypertension have symptoms that are useful in providing a sense of how serious this patient's hypertensive status, if any, presents.
We first need to evaluate any acute causes of an elevated blood pressure reading. The first might be an error in reading. Academically, guidelines recommend a 5 minute period of resting with no consumption of caffeine or nicotine products prior to the exam. It is usually difficult and impractical in a real clinical setting to follow this. There are also cases of "white coat hypertension" that occur when a patient's presence in a clinical setting cause acute increases in blood pressure.
Acute causes may also be drug or substance related, notably caffeine, nicotine, non-steroidal anti-inflammatory drugs (NSAIDs), and illicit substances such as cocaine and amphetamine. This patient denied any use of illicit drugs or medication history.
We may rule out other improbable causes such as sleep apnea. Patient denies sleep disorders. Chronic kidney disease is unlikely. Patient denies abnormalities in urination. Primary aldosteronism is unlikely as this patient denies muscle weakness or fatigue. Thyroid disease is unlikely as this patient denies mood, energy, appetite or weight change abnormalities. Patient also presents with no other abnormal cardiovascular findings, typical of thyroid disease.
Next turning to risk factors we clearly see an elevated weight (BMI: 26.5) and a regular diet of fast food. This patient does not smoke, use illicit drugs, or excess alcohol. We are not certain of his family history of blood pressure, though he does not admit to remarkable family medical problems.
Prognosis
Even if we assume this patient has hypertension, we are not certain of this patient's cholesterol levels to accurately determine his future risk of cardiovascular disease. Considering worst and best case scenarios of at goal and not-at-goal cholesterol levels, we can estimate this patient's 10 year risk of cardiovascular disease at 1% to 6%[2]. This means that if his blood pressure remains unchanged we have the following best and worst case scenarios. If his cholesterol is at goal (HDL is 40 and Total Cholesterol is 160) his risk of having a myocardial infarction, ischemic stroke, peripheral arterial disease, heart failure or death from cardiovascular causes is 1%. On the contrary, if his HDL is 30 and Total Cholesterol is 290, it is 6% likely for the aforementioned to occur.
Intervention Options
Despite no diagnosis, the lack of presenting end-organ damage complications make candidate interventions in this patient simple. He would clearly benefit from a reduction in his weight, increase in exercise activity and modification of his diet whether or not he has hypertension. Antihypertensive medications might not be helpful at this time as we do not have a formal diagnosis. While they would most likely not harm the patient, their benefit in preventing cardiovascular events in this patient would be questionable. Finally, it would be important to get a laboratory reading of this patient's cholesterol levels to make a formal prognostic risk assessment of future cardiovascular events.


Therapeutic Intervention
The most outcome benefiting intervention at this time would be to counsel this patient on lifestyle modifications as well as laboratory assessment of his cholesterol. The "Dash Diet" has been the lifestyle recommendation of choice for patients with hypertension[3]. For this patient, it recommends four servings each of fruits and vegetables daily, seven servings of whole grains, with limits of 2.5, 1.5, 0.5, 2, and 0.5 servings of dairy, meat, nuts/beans, fats, and sweets respectively. Also, the American College of Sports Medicine recommends 20 to 30 minutes three times weekly of endurance exercise training to drop systolic blood pressure by 10 mmHg[4].

Follow-Up and Monitoring
This patient should return in less than sixth months for a repeat measurement of his blood pressure and follow-up on results from his cholesterol testing.

Economic Analysis
The goal of economic analysis is to determine the value of certain health interventions or the burden of not intervening to aid in decision making. No precedence exists for the health economic evaluation on a patient level. This section follows the common taxonomy of economic analysis for decision making as well as the author's introduction of Real Options Analysis (What is this?). Our economic analysis will involve a population of 100 individuals that match the same characteristics of the patient here. Our application of Real Options Analysis will allow for evaluation on a patient level.

Preliminaries
Economic analysis requires the development of models which require assumptions and parameters. We will evaluate a horizon of 10 years under the following assumptions:
Diastolic blood pressure and the related pulse pressure will have no prediction on 10 year cardiovascular disease risk.
The mean and variance of all inputed values does not change throughout the horizon.
The only therapeutic options available are diet and exercise.
There is no difference in cost between patients' existing diet and the DASH diet.
DASH low sodium diet will reduce systolic blood pressure a mean -8.9 mmHg (95% confidence interval: -6.7 to –11.1) over 30 days[5].
Exercise as recommended will reduce systolic blood pressure a mean -10 mmHg (95% confidence interval: -7.5 to -12.5) over 30 days[4].
No additional blood pressure improvements will accrue after the initial benefit.
The blood pressure never worsens over the horizon.

Model
Figure 1 shows the model to be employed. The decision to be evaluated is comparing the impact of DASH diet and exercise versus doing nothing. The 'M' is a Markov Model (see introduction to Markov Modeling here) of which we evaluate shown in Figure 2. The markov model assumes a single change in blood pressure with a subsequent influence on cardiovascular disease outcomes over the 10 year horizon. At study initiation the blood pressure may stay the same, or drop to within 120-139 or <120. This blood pressure state has a corresponding impact on cardiovascular disease risk.
Table 1 shows the probabilities of these transition states. These were calculated from the mean and standard deviations of the studied outcome of diet[5] and exercise[4]. Instead of modeling a continuous blood pressure change, this allows for the modeling of states which may more accurately reflect the systolic pressure variability throughout the horizon.
Calculating such involved first combining the mean and standard deviations of the two interventions assuming independence in both of their outcomes. Then, we calculate the distributions based on the new mean and standard deviation. Finally we calculate the cumulate distribution of patients at different states.
The combined mean of -8.9 mmHg from [5] and -10 from [4] is a simple sum to -18.9 mmHg mean change. The standard deviations of 2.2 and 2.5 respectively were calculated from the formula . Thus the combined standard deviation was calculated to be 3.3.
Calculating the distributions involving using a statistical package, in this case R Cran, using the "rnorm" function with the inputs of mean=-18.9 and sd=3.3. The syntax is data <- rnorm(10000,18.9,3.3).
To calculate the percentage of patients transitioning to normotensive state we calculate the cumulative distribution of those that had >=20 mmHg. The syntax for this calculation in R is length(data[data>=20])/10000. To calculate the percentage of patients transitioning to a normotensive state we calculate the cumulative distribution of those that had <=10 mmHg. The syntax for this calculation in R is length(data[data<=10])/10000. Finally, calculating the cumulative distribution of patients transitioning to the prehypertensive state was simply the remaining. Table 1 shows the probabilities of these transition state calculations.
Table 2 shows the 10 year probabilities of cardiovascular risk given our uncertainty of patients' cholesterol levels. These were calculated using the framingham risk calculator. The two different transition probabilities take into account the uncertainty of the patients' cholesterol values. The lower and upper value correspond to Total and HDL inputs of 160, 40 and 280, 35, respectively. The other inputs were male 37 years old, non-smoker, and not on blood pressure therapy. The SBPs were inputed as 150, 135 and 118, respectively.

Figure 1. Decision Model for Economic Analysis (Case # s1htn.m.37)


Figure 2. Markov Model for Outcomes of Blood Pressure Lowering (Case # s1htn.m.37)

Table 1. Transition Probabilities of Blood Pressure States

Ending
State With Treatment Without
Treatment
140-159 1% 100%
120-139 60% 0%
<120 39% 0%

Table 2. Transition Probabilities of CVD States

SBP State p (CVD)
140-159 1% to 6%
120-139 1% to 4%
<120 1% to 3%

Budget Impact Analysis

Table 3. Input Parameters


Cost Effectiveness Analysis

Disclaimer: Patient information in this case is fictional and for educational purposes only. Any similarity to real persons or events is coincidental. Information contained in this knol is not to replace medical advice from a licensed health care provider. The author of this knol does not produce or endorse content from advertisements on this page.