An update on osteoporosis from Associate Professor Louis Roller

Osteoporosis is defined as a disease characterised by low bone mass and micro-architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk.

It is diagnosed by bone density tests that measure the density at the hip and spine. The result is called a ‘T-score,’ and will be in the range of normal, osteopenia (sub-normally mineralised bone), or osteoporosis.

Some statistics with respect to osteoporosis:

  • 4.74 million Australians over 50 have osteoporosis or poor bone health.
  • There is one fracture every 3.6 minutes in Australia (2013). By 2022 there will be one fracture every 2.9 minutes.
  • 144,000 fractures occurred due to osteoporosis or osteopenia in 2013.
  • Over the next 10 years, the total cost of osteoporosis and associated fractures is estimated to be $33.6 billion.

 

Osteoporotic fractures usually result from a combination of decreased bone strength and injurious falls. Vertebral (spinal) fractures are the hallmark fracture of osteoporosis and occur with a higher incidence and earlier in life than any other types of minimal trauma fracture.

Only about a third of vertebral fractures are associated with falls and most are precipitated by routine activities such as bending or lifting. These fractures may often not be recognised by patients.

Non-vertebral fractures are more common than vertebral fractures and their incidence is generally less responsive to therapy. Fractures at these non-vertebral sites, including hip, distal forearm, humerus, shoulder, ankle, pelvis and tibia, are approximately twice as common in women as in men, and their incidence also rises with age.

Osteoporosis Australia states that about 50% of women and 30% of men older than 60 years will have an osteoporotic fracture in Australia.  

Osteoporosis affects both women and men, however women are at a greater risk of developing osteoporosis than men, mainly due to the rapid decline in oestrogen levels after menopause.

When oestrogen levels decrease, the bones lose calcium (and other minerals) at a much faster rate—bone loss is approximately 1–5% per year after menopause. Many people, both men and women, are undertreated in primary care. Prevention of osteoporosis is a major role for pharmacists to increase awareness.

Osteoporosis may be primary osteoporosis, which includes postmenopausal and age-related osteoporosis or secondary osteoporosis, caused by identifiable agents, such as corticosteroids, or disease, such as rheumatoid arthritis.

Some risk factors for osteoporosis include back pain, corticosteroid treatment, early menopause, a family history of osteoporosis, height loss, low body weight, coeliac disease and other chronic gut conditions, low calcium intake, low vitamin D levels, physical inactivity, high alcohol intake, hypogonadism, impotence, and lack of libido (in men), hyperthyroidism, hyperparathyroidism, menstrual history (eg early menopause), a history of low-trauma fracture and recurrent falls.

Secondary causes include rheumatoid arthritis, chronic renal or hepatic disease.

Some lifestyle issues that can be addressed include smoking, excessive alcohol consumption, a diet lacking in calcium, lack of sunlight exposure and sedentary life-style over many years.

Medicines which may increase the risk of fractures following falls include benzodiazepines, carbamazepine, corticosteroids, morphine, NSAIDS, phenytoin, PPIs (proton pump inhibitors), SSRIs (Selective Serotonin Reuptake Inhibitors), thiazolidinediones (pioglitazone, rosiglitazone) and tramadol.

For diagnosis, patients need a referral for dual-energy X-ray absorptiometry (DXA) bone densitometry of the hip and spine to determine bone mineral density (BMD). Additional tests can include: Plain X-rays—to check for spinal fractures, calcium and PTH—to help determine if the parathyroid gland is functioning normally, vitamin D (using the 25-hydroxyvitamin D radioimmunoassay) —to help determine if there is a deficiency.

A full blood examination; urea, electrolytes and renal function; liver function tests, thyroid function tests; inflammatory markers; serum testosterone.  Osteoporosis risk calculators are an extremely useful aid: www.shef.ac.uk/frax/tool.jsp or http://garvan.org.au/promotions/bone-fracture-risk/calculator.

Treatment options include: Calcium, vitamin D, bisphosphonates (alendronate, etidronate, risedronate, zoledronic acid), strontium ranelate (Protos), hormone replacement therapy, raloxifene (Evista)- a selective oestrogen receptor modulator (SERM), Denosumab (Prolia)- an inhibitor of RANKL (monoclonal antibody-receptor activator of nuclear factor-kβ ligand), Teriparatide (Forteo -a recombinant human parathyroid hormone that activates osteoblast mediated bone formation).

Length of treatment with bisphosphonates and denosumab is still a moot point. There is now evidence coming in that these medications can be used beyond the arbitrary five years.

Assessing the patient’s levels of calcium and vitamin D are essential aspects and if this mineral and vitamin are not being attained sufficiently from diet, supplementation would be required.

Falls prevention is a major area of education for people with reduced bone mineral density. Falls risk is increased by medicines such as anticonvulsants, antidepressants, antipsychotics, antihypertensives, anti-Parkinsonism drugs, diuretics, and sedatives.

The main role of the pharmacist is to encourage the patient to address their risk factors and if being treated, ensure that they take their medications appropriately. In the case of oral bisphosphonates, the dose should be taken sitting up with a glass of water (only water) at least half an hour before food.

Also, if a patient is about to commence on a bisphosphonate or denosumab therapy, they should be advised to visit their dentist for a full oral examination and treatment of ony invasive dental problems. This is to prevent the onset of bisphosphonate –related osteonecrosis of the jaw (BRONJ).

Associate Professor Louis Roller, from the Faculty of Pharmacy and Pharmaceutical Sciences Monash University, was the 2014 recipient of the PSA Lifetime Achievement Award.