Clinical
Practice Guideline
for
OSTEOPOROSIS
Developed for the
Aerospace Medical Association
by their constituent organization
American Society of Aerospace Medicine Specialists
Overview: Osteoporosis is the most
prevalent disease of bone, affecting an estimated 10 million Americans. It is a “disease characterized by low bone
mass and microarchitectural deterioration of bone tissue, leading to enhanced
bone fragility and an increase in fracture risk.” Osteoporosis is caused by a combination of
increased bone resorption and inadequate bone formation which result in
deterioration of trabeculae. Although it
may be of clinical significance in men, osteoporosis is four times as common in
women and is especially active in the first ten post-menopausal years.
The
initial clinical presentation of osteoporosis typically is a fracture which may
be symptomatic or occult. In the latter
case, the typical finding is one or more spinal compression fractures on
radiographs taken for other reasons.
Fractures (especially hip, forearm, and spine fractures) also account
for most of the morbidity of the disease, which is further complicated in many
cases by subsequent poor healing.
Consequently, patients may have chronic pain, postural/skeletal
deformities, and in advanced cases restricted respiratory function from
thoracic deformities. In the elderly
population, osteoporotic fracture of the hip is frequently a pre-terminal
event. With occasional exceptions, most
of these problems will occur after a normal flying career has ended, but the
rapidity of bone loss immediately after menopause in women predisposed to
osteoporosis means that prophylaxis concerns will routinely arise during a
flying career.
|
Table 1. Risk factors for osteoporosis |
|
Personal history of
adulthood fracture First-degree
relative with history of adulthood fragility
fracture Current cigarette
smoking Low body weight
(less than 58 kg [127 lb]) Corticosteroid
therapy greater than 3 months. Female sex Estrogen deficiency
(menopause [especially before age 45 years], bilateral oophorectomy,
prolonged premenopausal amenorrhea [greater than one year]) Caucasian or Asian
race Age Lifelong low
calcium intake Alcoholism Inadequate physical
activity |
The
commonest form of osteoporosis appears to be caused by low estrogen state
(e.g., postmenopausal, bilateral oophorectomy); additional risk factors which
increase the likelihood or severity are listed in Table 1. Osteoporosis may also be secondary to a
variety of other medical conditions.
Certain diseases like hyperthyroidism, hyperparathyroidism,
hypogonadism, and Paget’s disease, any of which might reasonably be encountered
in an aviator, can cause or mimic osteoporosis.
A number of other diseases are in the broader differential diagnosis,
including acromegaly, Cushing’s syndrome, osteomalacia, and malignancies such
as lymphoma and multiple myeloma.
Furthermore, the use of certain medications such as heparin,
glucocorticoids, vitamin A, and chemotherapeutic agents may occasionally be
complicated by bone loss.
To
identify osteoporosis before fractures occur, screening for this disease is
important. Current guidelines from the
National Osteoporosis Foundation, the American Association of Clinical
Endocrinologists, the National Institutes of Health, the U.S. Preventive
Services Task Force and others agree that women greater than 65 years old,
women with a history of postmenopausal fracture, or any adult with a fracture
occurring in the absence of sufficient trauma should be screened for
osteoporosis. Recently revised
guidelines also recommend that postmenopausal women with risk factors for
fracture be considered candidates for screening. To clarify the important risk factors in
postmenopausal women, the Osteoporosis Risk Assessment Instrument (ORAI) (based
on age, weight and estrogen use) and the Simple Calculate Osteoporosis Risk
Estimation (SCORE) (based on race, fracture history, rheumatoid arthritis
comorbidity, age, weight and estrogen use) surveys have been developed and
validated for yielding good indications for screening bone density measurement.
In
the military aviator population, one is most likely to encounter perimenopausal
women with concerns driven by a family history of postmenopausal
osteoporosis. Consensus on how to
proceed in this population has not been reached. However, a 43-year-old, Caucasian female
weighing 120 pounds with irregular menstrual cycle and a family history of
osteoporosis may benefit from screening and, if appropriate, treatment. The health care provider must exercise
clinical judgment on individual assessments.
Dual-energy
x-ray absorptiometry (DEXA or DXA Scan) is the most popular method of
densitometry and is readily available in most medical communities for
osteoporosis screening. DEXA scan
results have been well-correlated with fracture risk. The results of a DEXA scan are reported using
T-scores and Z-scores. T-scores are
standard deviations from a normal young healthy population mean. Z-scores are standard deviations from an
age-matched, sex-matched, and sometimes race-matched population mean. Women with a T-score of -2.5 or lower (i.e.,
a larger negative number) are said to have osteoporosis, and those with a
T-score between -1.0 and -2.5 are said to have osteopenia. Osteopenia should not be thought of as a
separate disease, but an early form of osteoporosis, with the significant
caveat that some women in the osteopenic range may not progress to
osteoporosis.
In
addition to bone densitometry, laboratory screening for underlying causes of
osteopenia and osteoporosis has also been widely supported, although a precise
algorithm has not been uniformly endorsed.
The utility of a workup depends on the clinical scenario. For instance, it makes little sense to pursue
an exhaustive evaluation to identify a secondary cause of early-stage
osteopenia in a 45-year-old perimenopausal female who was screened because of a
positive family history; after all, it was the patient’s underlying risk that
prompted the screening in the first place.
On the other hand, a fragility fracture which leads to the
identification of osteoporosis in a male or premenopausal female should be
thoroughly evaluated. A reasonable
approach would be to evaluate individuals initially diagnosed with osteoporosis
with a complete blood count, serum chemistries (electrolytes, blood urea
nitrogen, creatinine, calcium, phosphorous, total protein, albumin, liver
transaminases and alkaline phosphatase), 25-hydroxyvitamin D levels,
urinalysis, and 24-hour urine for calcium excretion and creatinine. Additional studies should be driven by
history and clinical exam and may include thyroid function tests, parathyroid
hormone, serum testosterone (men), serum estradiol, urine free cortisol, or
others. For individuals who fail to respond
to alendronate therapy, biochemical markers of bone metabolism (specifically
urinary N-telopeptide crosslinks) should be evaluated.
Current
strategies in osteoporosis treatment are increasingly focusing on preventing
and mitigating the loss of bone in the post-menopausal women, and therapy is
generally tailored to the bone density as determined by DEXA scan. All women can probably benefit from a healthy
diet high in calcium, supplementation with calcium and with vitamin D, smoking
cessation (when applicable), moderation of alcohol (if consumed), and regular
weight-bearing exercise of any intensity.
As
noted earlier, osteopenia and osteoporosis are best viewed as a continuum. Rather than distinguishing between the two
entities, prophylaxis recommendations are based on a T-score of -2.0 or worse,
though a score of -1.5 may be used as a treatment threshold if multiple risk
factors are present. Both hormone
replacement therapy (HRT), with estrogen alone or combined with a progestin,
and bisphosphonates have been considered first-line therapies for the
management and treatment of osteoporosis.
However, recent results from the Women’s Health Initiative have raised
concerns about breast cancer and cardiovascular risks due to HRT. For this reason, bisphosphonate therapy is
the preferred first-line therapy in most cases.
Alendronate is a
bisphosphonate approved by the US Food and Drug Administration (FDA) for the
prevention and treatment of osteoporosis in postmenopausal women and is on the
Official Air Force Approved Aircrew Medication List. Common side effects of alendronate for which
aircrew should be monitored when using this medication include thoracic and
abdominal pain (due to esophageal or gastric ulcerations), nonspecific
gastrointestinal symptoms (nausea, vomiting, diarrhea, constipation), melena,
hematochezia, musculoskeletal pain, headache, and allergic reaction. These risks are minimized by technique of
administration, which is outlined below.
Teriparatide (Forteo®), a recombinant parathyroid hormone, is also
available; unlike bisphosphonate therapy, this agent consistently induces
regrowth of bone. Major disadvantages of
parathyroid hormone, besides expense and the necessity for refrigeration,
include consistent elevations of serum calcium (with excursions into the
abnormal range about 11% of the time), and the risk of inducing
osteosarcoma. This agent is usually
reserved for those with progressive failure of bisphosphonates, and for those
with extreme levels of osteoporosis, and as such is rarely indicated. Therapy with teriparatide is not waiverable
in the military. Calcitonin therapy is
very rarely employed; the usual indication is pain control in the face of
recurrent fragility fractures, and thus neither the condition nor the therapy
would be waiverable.
Monitoring
the efficacy of osteoporosis treatment is medically and aeromedically
important, though there is some disagreement on how to monitor
appropriately. The commonly accepted
method to monitor sufficiency of treatment is to repeat bone densitometry at
two year intervals. Some patients will
experience an increase in bone density on bisphosphonate therapy, but in
general treatment is considered satisfactory if it results in arrest of bone
loss. DEXA scanning should include the
lumbar spine and bilateral hips. While
bone density measurement of the left hip can be acceptable for making the
diagnosis of osteoporosis, assessment of therapy requires serial measurement of
lumbar spine and total hip scores. The
lumbar spine value is based on AP lumbar spine, not the lateral. (The same is true for initial diagnosis;
unlike the left hip T-score, the lateral spine T-score is not useful for
diagnosis either.) Absolute BMD, rather
than T-score, is assessed for response to therapy; a loss of 4% of hip density,
and/or 5% of spine density, is considered significant. If this happens despite alendronate therapy,
work-up should address poor absorption of the drug, and include re-evaluation
of vitamin D levels.
Aeromedical Concerns: While certain
aviation career fields, such as loadmaster or aeromedical evacuation
crewmembers, routinely involve weight bearing labor, any aircrew member may be
called upon for physical exertion. All
aircrew have the potential need to quickly egress their aircraft, and help
others do so as well. In many cases the
egress route may involve climbing up or down, with drops or falls of several
feet, and may necessitate the rapid movement of heavy objects or assistance to
other crew members. These conditions
would further increase the likelihood of pathologic fractures in an
osteoporotic aviator. Furthermore, a
fracture while egressing emergently would pose an additional threat to the
safety of the injured aviator and other aircrew by delaying evacuation.
In
high-performance aircraft, aviators have a known, increased risk of cervical
and lumbar injury due to the large forces experience in high “G”
maneuvers. No body of data exists
regarding the response of osteopenic/osteoporotic aviators in this environment
due to a paucity of affected individuals who have been exposed, although
anecdotal cases have certainly occurred (e.g., symptomatic vertebral fracture
during initial centrifuge training in an osteoporotic male). It is almost certain that acceleration
stresses on bone tissue weakened by osteoporosis would result in a higher
incidence of these types of injuries. A
fragility fracture occurring under high-G conditions could even result in a
catastrophic mishap.
Alendronate
is a reasonably effective drug, and the risk of side effects is minor as long
as proper technique of administration is followed. It should be taken on a fasting stomach with
water only, and no other food or beverage should be consumed for an hour after
medicating to prevent inactivation of the drug.
To avoid esophageal damage, an upright posture needs to be maintained
for at least an hour after ingestion.
(The drug’s inactivation by food can be useful; to further avoid the
risk of esophageal ulceration, and the need to continue remaining upright, individuals
are typically advised to eat a snack or meal an hour after taking the
drug.) In high-performance aircraft some
concern exists about the risk of inducing regurgitation of gastric contents due
to G-suit abdominal compression, negative Gz forces, and reclined seating. In order to minimize this risk, it is
recommended that high-performance aviators dose alendronate on a day when no
flying is planned. If conflict with the
flying schedule is unavoidable, the aviator should medicate at least 30-60 minutes
prior to flying, and should eat a snack just before taking off, which will
effectively neutralize any remaining drug.
Medical Work-up: The required work-up
and documentation for waiver consideration of osteoporosis includes a good
history to include any symptoms, family history, all medications, activity
level, and menopausal status. Necessary
labs include CBC, electrolytes, BUN, creatinine, phosphorus, calcium, total
protein, albumin, liver transaminases, and alkaline phosphatase. Bone density measurements are also important,
particularly of the hip and lumbar spine.
Aeromedical Disposition:
Air Force: Waiver will not be
considered for initial flying training in most cases. If an underlying cause for osteoporosis was
identified, the underlying disease must be eligible for waiver, and must be
treated effectively enough that the osteoporotic process is reversed. For trained aviators, the finding of
osteopenia or osteoporosis, whether or not of a degree that requires
prophylaxis, would not require airframe restriction, but the occurrence of a
fragility fracture would require restriction from high-performance and ejection
seat aircraft. For non-pilot aircrew,
the variety of duties requires individual consideration; for instance, severe
osteoporosis or the occurrence of a fragility fracture would contraindicate
parachute duty. For aviators requiring
alendronate therapy, response to therapy and waiver status should be reassessed
every two years. For those with
osteopenia not requiring therapy (e.g., T-score <2.0), BMD should be
initially reassessed at two years; if stable, recommend waiver duration of
three to five years.
Army: Osteoporosis has not proved to be very
significant in the Army aviation population.
It has no Army APL of its own, but is discussed in the Backache and
Osteoarthritis APL. Chronic medication
for back pain beyond acetaminophen and NSAIDs are rarely considered for waiver,
however waiver for chronic bisphosphonate therapy may be considered on an
individual basis.
Navy: The US Navy waiver guide does not
include protocol specific for osteoporosis.
However, the condition and medication usage has been waivered on a
case-by-case basis.
Civilian: Osteoporosis and its treatments are not
disqualifying unto themselves. An acute
fracture would be disqualifying until the fracture stabilizes and the pain can
be treated without narcotic analgesics. If
as a result of a fracture the airman is physically limited in any way the
airman may require a medical flight test and ultimately a Statement of
Demonstrated Ability. The medications
used, especially Alendronate, for the prophylaxis of osteoporosis is
acceptable. In the
Waiver Experience:
Air Force: A review of AIMWTS revealed
26 cases of osteoporosis/osteopenia, 2 FC I/IA, 12 FC II, and 12 FC III. Of the 26 cases, 7 were disqualified; 1 FC I
(history of cerebellar tumor) 2 FC II (1 for multiple medical problems and 1
for vertebral fracture with significant pain) and 4 FC III (2 for use of
unapproved medications, one for inadequate vision and 1 for bad headaches).
Both of the disapproved for medications were for drugs now approved.
Army: The Army’s Aeromedical Epidemiological
Data Registry was queried for the period of 1960 to 2009. This case series contains 160,000
individuals. The series included 10,200
females. This is a long span of time
during which aeromedical policy has evolved.
There were 4 cases of osteoporosis.
Of those, 3 were retained in aviation.
Of these 2 were rated aviators.
Note that flight applicants were included in the data set, but not
included as rated aviators.
Navy: No numbers to report at this time.
Civilian: The current Path Code system has the
same code for Lyme Disease and for Osteoporosis. Those numbers as of August 2009 are: 205 for
first class, 172 for second class and 666 for third class
|
ICD
9 Codes for Osteoporosis |
|
|
733.00 |
Osteoporosis, unspecified |
|
733.01 |
Osteoporosis, postmenopausal |
|
733.02 |
Idiopathic osteoporosis |
|
733.03 |
Disuse osteoporosis |
|
733.09 |
Other osteoporosis |
|
733.90 |
Osteopenia |
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Prepared by Drs. Glenn Donnelly, Jeb Pickard
and Karen Fox
12 Sep 09