Cardiovascular Risk Factors in Airline Pilots

Abstract

The health of an airline pilot is imperative to the safe travels of millions of people worldwide. Medical providers evaluate the cardiovascular risks for airline pilots and the medical requirements to obtain and maintain licensure as an airline pilot. It is the role of the occupational health nurse practitioner to evaluate and reduce the risk of cardiovascular disease in this population.

Introduction

The U.S. Department of Transportation’s Bureau of Transportation Statistics reports that in the year 2015, U.S. airlines and foreign airlines servicing the U.S. carried 895.5 million passengers (U.S. Bureau of Transportation Statistics, 2016). The data show that the number of U.S. passengers continues to rise each year for domestic and international flights. The Federal Aviation Administration (FAA) is charged with providing safe and efficient flights for U.S. travelers. Their role in safety includes regulation of civil aviation; issuing and enforcing regulations and standards in manufacturing and maintenance of aircraft; operating the air traffic control system; developing new aviation technology; and certification of U.S. pilots (FAA, 2014).

A large part of the FAA safety initiatives includes the licensure of pilots, ensuring that licensed pilots are competent in their occupation. Included in the basic competence of licensure is a comprehensive medical examination performed by an Aviation Medical Examiner (AME). Cardiovascular diseases are an important medical condition requiring careful evaluation due to the risk of sudden incapacitation of a pilot during a cardiac event. Evaluating the risk factors specific to airline pilots and implementing heart healthy programs to mitigate modifiable risk factors are an important part of the occupational health nurse practitioner role.

Background and Epidemiology

Cardiovascular disease is the number one killer of both men and women, with more than 600,000 people dying from the disease in the U.S. every year (National Center for Chronic Disease Prevention & Health Promotion, Division for Heart Disease & Stroke Prevention, 2015). Forty-seven percent of Americans have major risk factors for heart disease, including a smoking history, hypertension, or hypercholesterolemia (National Center for Chronic Disease Prevention & Health Promotion, Division for Heart Disease & Stroke Prevention, 2015). There are many contributing factors to the development of cardiovascular disease, including an unhealthy diet, physical inactivity, alcohol, tobacco use, genetics, family history, increased stress, and medical conditions such as diabetes and hypertension. Often, cardiovascular disease is insidious, with many people having a sudden cardiac event prior to knowledge of having heart disease.

Airline pilots have a responsibility to their passengers and crew to ensure their safety while flying. According to the FAA, pilots must meet medical standards to obtain or maintain their license (FAA, 2011). Airline pilots are at an increased risk of heart disease related to the requirements of their occupation, such as extended flights, shift work, irregular meal times, stress, and biorhythm disturbances with changing time zones and increased light exposure (Choi & Kim, 2013). With the insidious nature of cardiovascular disease and the risk of a sudden cardiac event occurring mid-flight, it becomes increasingly important to analyze the risk factors of airline pilots and attempt to mitigate those risks.

Review of the Literature

Risk factors of Cardiovascular Disease

There are two types of risk factors involved in cardiovascular disease: modifiable and non-modifiable. Modifiable risk factors include poor diet, physical inactivity, smoking, excessive alcohol consumption, stress, and obesity. Non-modifiable factors include family history, genetics, gender, race, and increasing age (American Heart Association [AHA], 2016).

Ekstrand, Bostrom, Arborelius, Nilsson, and Lindell (1996) examined the differences in risk factors between pilots and the general population. They found that pilots exhibited an increased incidence of left ventricular hypertrophy (LVH) on electrocardiogram (ECG), 29.2%, as compared with 10.9% in the control group. It was also discovered that pilots had a systolic blood pressure (SBP) >145 mm Hg, more frequently than the control group, 11.5% and 4.4% respectively. Serum cholesterol was higher among the pilots, 5.83 mmol/L, with the control group results of 5.54 mmol/L (Ekstrand et al., 1996). These factors, hypertension, hypercholesterolemia, and LVH, are independent risk factors for cardiovascular disease (Mayo Clinic, 2015). It is hypothesized by the authors that pilots have an increased risk due to their occupational exposures, such as increased level of stress, flight schedules, nutritional factors, noise levels, shift work, and time zone changes that disrupt circadian rhythm.

Evaluation of Risk Factors

There is increased importance of identifying those pilots who have a higher risk of cardiovascular disease as many pilots with cardiovascular disease are asymptomatic until they have a sudden cardiac event.

Wirawan, Larsen, Aldington, Griffiths, and Ellis (2012) studied the effectiveness in using the Framingham risk chart to predict cardiovascular events of airline pilots. This study found that 60% of those with cardiovascular disease were not detected with screening and initially presented with a sudden cardiac event. Only 13.3% had an increased cardiovascular risk score and 26.7% of pilots’ cardiovascular disease were discovered during other routine screening, such as laboratory studies (Wirawan et al., 2012). They concluded that the risk assessment tool had low sensitivity and that a more comprehensive cardiovascular workup is required for airline pilots.

Wirawan, Aldington, Griffiths, Ellis, and Larsen (2013) performed another study to research the topic of pilots with excessive cardiovascular risk, this time studying the cardiac examinations performed when a pilot is determined to have an increased risk. They compared the cardiovascular disease risk factors between high-risk groups and low-risk groups of pilots. They found that the high-risk group had higher total cholesterol, increased blood pressure, higher incidence of diabetes, and a higher incidence of smoking. They emphasized the importance of prevention programs focused on decreasing these specific risk factors. They discovered that there is difficulty in accurately predicting a cardiovascular event based on utilization of risk models available. Forty-seven percent of those who had a cardiovascular event had lower risk levels, never achieving a 10% 5-year risk level. ECGs were unreliable, with half of the pilots with a positive ECG showing normal or trivial disease with coronary angiogram. Three pilots with normal ECG readings, but high-risk scores, had significant disease on coronary angiogram (Wirawan et al., 2013). The current approach relies on ECG as the diagnostic tool to investigate risk, which may not detect disease and may place the pilot at unnecessary risk with invasive coronary angiography as follow-up testing. This study shows that a comprehensive cardiac examination and view of the patient is required to fully evaluate for cardiovascular disease.

Wirawan, Wu, Abernethy, Aldington, and Larsen (2014) studied a specific approach in the use of coronary artery calcium score (CACS) to improve prediction of cardiovascular disease in asymptomatic pilots. It was noted that high calcium scores (>400) place a pilot at a higher risk for coronary heart disease (CHD) and can identify pilots at high risk for cardiovascular disease. Coronary artery calcium score can be utilized in addition to current risk assessments of Framingham risk score and exercise stress test to assist in classifying asymptomatic pilots into cardiovascular risk categories and initiating primary prevention programs to reduce their risk factors.

Strategies for Risk Reduction

Choi and Kim (2013) conducted a study to evaluate the influence of physical examination and dietary consultation in the reduction of risk factors associated with cardiovascular disease. They examined the various modifiable risk factors, such as smoking, physical exercise, obesity, and alcohol. They specifically studied the impact of dietary counseling, combined with an exercise program, on the reduction of these risk factors. The group who received counseling and exercise intervention significantly decreased their total cholesterol and body mass index (BMI) and increased their high density lipoprotein (HDL). Viewing the patient as an individual, providing an exercise program and nutritional counseling specific to the individual, will have an impact in reducing the modifiable risk factors associated with cardiovascular disease.

Implications for the Occupational Health Nurse Practitioner

Aviation Medical Examiner

A comprehensive medical evaluation is required by the FAA for airmen to obtain or maintain medical certificates for licensure. It is the responsibility of the AME to issue or deny medical certificates or, in certain circumstances, defer to the FAA for review (FAA, 2011). Airmen applying for medical certification are divided into three classes. First-class certification holds an airline transport license and must be renewed every 12 months for pilots less than 40 years of age; second-class airmen hold a commercial pilot license and must renew every 12 months regardless of age; third-class airmen hold a private pilot license and must renew every 60 months if less than 40 years of age and every 24 months if older than 40 (FAA, 2011). The cardiovascular requirements for all classes are to have no history or diagnosis of myocardial infarction (MI), angina pectoris, cardiovascular heart disease that has required treatment, cardiac valve replacement, permanent cardiac pacemaker, or heart transplant. In addition to this requirement, first-class airmen must also demonstrate a normal ECG with their first application after age 35, and on an annual basis after age 40 (Electronic Code of Federal Regulations, 2017). The AME must document a thorough cardiac assessment and take into consideration the demands of flight, such as increases in heart rate with takeoff and landing or G-forces associated with aerobatic or agricultural flights (FAA, 2011).

Occupational Health Nurse Practitioner

Although the AME is responsible for performing the physical examination required to issue a medical certificate for a pilot, they can delegate portions of the testing, laboratory workup, and history taking to a nurse practitioner (FAA, 2011). AMEs are also in practice as physicians in family medicine, internal medicine, and occupational health clinics. The occupational health nurse practitioner working with an AME plays a crucial role in the reduction of modifiable risk factors and management of cardiovascular disease in an airline pilot. The occupational health nurse practitioner’s role as counselor, with a holistic or all-inclusive approach to patient care, will be an asset in the implementation of a more comprehensive cardiac investigation, which may include Framingham Risk Scores, CACS, ECG, nutrition counseling, implementing a fitness program, stress reduction techniques, evaluating cholesterol levels, and monitoring blood pressure. It is the responsibility of the occupational health nurse practitioner to have knowledge of the requirements of the FAA with regard to treatment of a cardiovascular disorder in this population. The FAA does allow medical certificates to be issued under strict guidelines to fully evaluate the disorder with a focus on the degree of functional recovery and prognosis (FAA, 2011). The occupational health nurse practitioner should also be aware of immediate disqualifiers that must be reviewed by the FAA, such as a medical history of coronary artery bypass surgery, permanent cardiac pacemakers, and artificial heart valves (FAA, 2011).

The occupational health nurse practitioner may be responsible for routine care of these pilots and must be aware of FAA guidelines for each system of the body and treatments allowable for an airline pilot. The Guide for Aviation Medical Examiners provides information for exam techniques of each system, treatments allowed, and medical dispositions depending on the results of the exam (FAA, 2011).

One common diagnosis that leads to cardiovascular disease is hypertension. The occupational health nurse practitioner should be aware of current practice guidelines to treat hypertension, while still taking into consideration the FAA requirements of treatment of hypertension. The American College of Cardiology (ACC) and AHA’s 2017 practice guideline begins with stressing lifestyle modifications for every patient with hypertension (ACC, 2017). The ACC/AHA guidelines also classify Stage 1 hypertension as having an SBP > 130 mm Hg or a diastolic blood pressure > 80 mm Hg, and Stage 2 hypertension as having an SBP > 140 mm Hg or diastolic blood pressure > 90 mm Hg (ACC, 2017). Treatment with medications for Stage 1 hypertension begins if the patient has a high risk for a cardiovascular event or a history of a cardiovascular event (ACC, 2017). There are medications that the FAA states are acceptable and medications that are unacceptable. If initiating medication therapy for hypertension, the occupational health nurse practitioner should advise the pilot of the FAA’s no fly rule of seven trial days to ensure no adverse side effects from the medications (FAA, 2015).

Coronary heart disease is another diagnosis with strict FAA guidelines. Coronary heart disease follows a very specific protocol for medical certification that often requires the AME to defer to the FAA for a decision. There are four categories of CHD per the FAA, which include the following:

• Open revascularization of any coronary artery and left main coronary artery stenting, with or without MI

• Percutaneous intervention with or without MI

• MI without open or percutaneous intervention

• MI from non-coronary artery diseases

It is important for the occupational health nurse practitioner to keep in mind the required recovery time for open revascularization of coronary artery and left main coronary artery stenting is 6 months, while the other three categories have a required recovery time of 3 months (FAA, 2011).

The occupational health nurse practitioner should be aware of the resources and requirements of the FAA for medical certification when evaluating a pilot at any point, even when they are not being seen for initial certification or renewal. The FAA requires the AME to report a thorough history and physical, test results each time a pilot is seen for certification, and any time there are changes in a pilot’s condition that may affect their medical certification and ability to fly (FAA, 2011). Access to these records is important for the occupational health nurse practitioner to provide continuity of care, considering the mobility of this career. The Guide for Aviation Medical Examiners is an invaluable resource on the FAA website that provides information on the evaluation and treatment of various conditions, enabling the airline pilot to continue to fly safely (FAA, 2011).

Summary

Cardiovascular disease has been identified as a leading cause for airline pilot grounding and denial of a medical certificate (Choi & Kim, 2013). The importance of conducting a thorough cardiovascular evaluation for airline pilots cannot be overstated. A sudden cardiovascular event mid-flight can have a significant impact on the safety of both crew and passengers, not to mention the delay in care for the pilot. It is important to identify the cardiovascular risk score of the pilot, identify specific risk factors that may be modifiable, and implement programs to mitigate these risks. The occupational health nurse practitioner plays a significant role in the health and safety of this worker population. The occupational health nurse practitioner has a unique perspective of the patient as a whole and can provide appropriate individualized interventions to reduce the risk factors specific to this population.