Acuerdos comerciales entre el Ecuador y sus países socios

Osteoporosis is a major global health issue which is becoming increasingly important as the population ages. The World Health Organisation (WHO) estimates that 70 million people worldwide have osteoporosis. Hip fractures are the most severe consequence of osteoporosis and are associated with lengthy hospital admissions, difficulty in performing activities in daily life, nursing home placement and a high rate of mortality. The annual worldwide incidence of hip fracture is 1.5 million, a number projected to grow to 2.6 million by 2025 and to 4.5 million by 2050 (Gueldner, Grabo, Newman, & Cooper, 2008). Estimates from the Australian Bureau of Statistics 2004- 2005 National Health Survey suggest that about 600,000 Australians (3% of the population) have doctor-diagnosed osteoporosis. Of these, 85% are women and 15% are men (A picture of osteoporosis, 2008). Osteoporosis is a condition where the bones become fragile and brittle and fracture more easily than a normal bone (Figure 2.5). Even a minor bump or fall can cause serious fracture. In Australia, half of all women and one third of men over 60 will have a fracture due to osteoporosis (Calcium, Vitamin D and Osteoporosis - A guide for consumers, 2008).

Osteoporosis is a skeletal disorder characterised by compromised bone strength, which predisposes the sufferer to increased risk of fractures (Camacho & Miller, 2007). To understand osteoporosis, it is important to appreciate the dynamic nature of bones. Bone is a tissue composed of a solid, thick outer layer known as cortical bone and an internal honeycomb-like structure called trabecular bone. The bone tissue is in a continual process of breakdown and rebuilding, ensuring that bones are repaired and remain strong (A picture of osteoporosis, 2008). Bone strength is a product of both bone density and bone quality. Bones gives shape and form to the body, support the body’s weight, protect vital organs, serve as a storage area for minerals such as calcium and phosphorus, provide stem cells from bone marrow for healing and cell growth, and work in conjunction with the muscular system to assist the body with movement (Gueldner, Grabo, Newman, & Cooper, 2008). Because of its hard texture, bone is commonly thought of as an inactive tissue. However, it is a dynamic tissue in which the cells are involved in extensive interactions with one another, and with hematopoietic (blood forming) and stromal (connective tissue) cells in the bone marrow. These interactions are prominent in maintaining bone mass (Gueldner, Grabo, Newman, & Cooper, 2008).

Bone density is expressed as grams of mineral per area or volume; bone quality refers to factors such as architecture, turnover, damage accumulation and mineralisation (Camacho & Miller, 2007). Bone density can be measured by various methods but bone quality is not readily quantifiable (Camacho & Miller, 2007).

Figure 2.5 – Normal versus osteoporotic bone

(Source: Osteoporosis Australia)

2.9.1 Diagnosis of osteoporosis

Osteoporosis is most commonly diagnosed using bone densitometry. Various techniques are available to quantify bone mass such as DXA (dual-energy X-ray absorptiometry), Q-CT (quantitative computed tomography), p-DXA (peripheral dual- energy X-ray absorptiometry). The most accurate and precise technique is the central dual-energy X-ray absorptiometry (DXA) scan (Camacho & Miller, 2007).

The basic principle of the DXA scan is that two beams of X-rays are generated and allowed to pass through the area of interest, usually the spine or the hip. The density of the bone, usually determined by its calcium content, causes different attenuation of these X-ray beams. As the beams pass through the bone and soft tissues, two photoelectric peaks are quantified, and the device is able to subtract the contribution of the soft tissue to the measured density. BMD is expressed as an area measurement in grams per square centimetre (Camacho & Miller, 2007).

Normal Bone Osteoporotic Bone

2.9.2 Fracture risk

Fracture risk increases significantly with age, and the incidence rises sharply after the menopausal years. Hip fractures occur about a decade later, with a sharp increase in incidence around the age of 70. A strong correlation exists between fracture risk and bone density, and this relationship is even stronger than that between cholesterol and heart disease (Figure 2.6).

Figure 2.6 – Relationship of fracture risk with age and bone density

2.9.3 T-Scores and Z-Scores

The T-score is the number of standard deviations that the BMD falls below or above the mean of a young healthy adult. This score is used for diagnosing osteoporosis. Z-scores compare the BMD with age and sex-matched controls and give an idea of the age appropriateness of bone loss (Camacho & Miller, 2007). The World Health Organisation (WHO) criteria are the widely accepted basis for osteoporosis diagnosis, based on the T-score. Osteoporosis is defined by a T-score equal to or less than -2.5. T- scores above this cut-off but below 1.0 define osteopenia or low bone mass. Normal BMD is 1 SD above or below the mean (T-score of -1 to + 1). An individual who has a T-score of -2.5 or less and has suffered from an osteoporotic fracture is considered to have severe or established osteoporosis (Camacho & Miller, 2007).

2.9.4 Risk factors for osteoporosis

The risk of getting osteoporosis can be reduced by paying attention to certain risk factors. Some risk factors are modifiable because changes in lifestyle or behaviours can reduce risk. The fixed risk factors are those people are born with and cannot be modified. People with fixed risk factors can substantially reduce their risk of getting osteoporosis by focusing on improving their modifiable risks factors (Table 2.2).

Table 2.2 – Risk factors for osteoporosis

(Extracted from (A picture of osteoporosis, 2008))

Modifiable Risk Factors Fixed Risk factors

Physical inactivity Family history and genetics

Low calcium and vitamin intake Physical disability

Vitamin D deficiency Old age

Tobacco smoking Female sex

Excessive alcohol consumption Previous minimal trauma fracture

Low body mass index Other medical conditions