Volume 4 · Nº 1 Supl · March 2012
History: Osteoporosis is characterised by a deterioration in bone microarchitecture which puts the bone at risk of suffering fractures. Bazedoxifene is a third generation selective estrogen receptor modulator which has been approved for the treatment of postmenopausal osteoporosis.
Objectives: To evaluate the efficacy of bazedoxifene in the primary and secondary prevention of osteoporotic fractures in postmenopausal women.
Search strategy: Searches were carried out on MEDLINE, Cochrane Central, registers of clinical trials and books of summaries to find random controlled trials published between 2000 and 2011.
Selection criteria: Randomised clinical trials aimed both at the primary and secondary prevention of osteoporosis were selected. Studies were chosen which compared women who received bazedoxifene with those given other drugs for osteoporosis or a placebo.
Compilation and data analysis: The selection of studies and the extraction of data was carried out by two researchers working together. A meta-analysis of the results of fracture and the secondary effects was carried out, establishing the relative risk. The quality of the studies was evaluated on the basis of the criteria proposed by the Cochrane collaboration.
Principal results: Five trials were included in the review (13,543 patients): 3 were concerned with primary prevention (5,622) and two with secondary prevention (7,921). Only those studies of secondary prevention evaluated the fractures as principal objective.
Compared with the placebo bazedoxifene reduced the number of new vertebral fractures detected in the follow up at three years in women with osteoporosis: with a dose of 20 mg the number of patients necessary to treat (NNT) was 56 (CI 95%, 34-146), and at a dose of 40 mg the NNT was 63 (CI 95%, 37-231). In the meta-analysis the relative risk compared with the placebo was 0.59 (CI 95%, 0.44-0.79). There was no difference in the number of symptomatic vertebral fractures or in the number of non-vertebral fractures in the analyses predicted at the start of the study. We found no data on the effect of bazedoxifene on the number of fractures in primary prophylaxis.
For the adverse effects, the meta-analysis did not confirm an increase in the risk of deep vein thrombosis which was seen in the reference study (RR: 8.53). There was an increase in episodes of hot flushes (RR:1.88) or muscular cramps (RR:1.32). No reduction in the incidence of breast cancer was observed, nor in endometrial cancer or endometrial hyperplasia with treatment with bazedoxifene compared with the placebo.
Authors’ conclusions: Bazedoxifene is an efficacious drug in the reduction in the risk of asymptomatic vertebral fractures in primary prophylaxis. In addition, it has been shown to reduce the loss of bone mineral density and to slow bone remodelling in the primary and secondary prevention of osteoporosis. New studies which analyse the risk of non-vertebral fractures and compare the drug with others in the first line of treatment of osteoporosis are necessary in order to understand the true power of their antifractural effect.
Osteoporosis (OP) is a common disease, responsible for a great number of the fractures occurring in people over 50 years of age. Through various pathogenic mechanisms a reduction in bone mass occurs, which is accompanied by an increase in bone fragility. Osteoporotic fractures in the vertebrae, the hip, the forearm and the humerus are the most frequent. They are a massive health problem due to their repercussions, not only on the health and quality of life of the patients, but also due to the economic and social costs of their treatment and aftercare.
Form a conceptual point of view, it is necessary to distinguish between OP as a clinical entity and densitometric OP. With respect to the former, this consists of a systematic bone disorder characterised by a deterioration in bone resistance which predisposes it to fracture, in the light of the fact that bone resistance is the result of an integration of bone density and bone quality . The cause may have an influence on the loss of bone mass or on other elements, such as the bone’s microarchitecture, on which the quality of the tissue depends. On the other hand, the latter is an operative definition proposed by the working group of the World Health Organisation (WHO) meeting in 1992 . This took into account a number of levels or cut-off points of bone mineral density (BMD) for postmenopausal white women. Thus, considered as normal are those values of BMD above -1 standard deviation (SD) in relation to the average for young adults (T-score > than -1); osteopenia corresponds to values of BMD between -1 and -2.5 SD (T-score between -1 and 2.5); OP, values of BMD lower than -2.5 SD (T-score lower than -2.5); and established OP, when in addition to the above conditions are combined with one or more osteoporotic fractures . This definition is mainly useful as a epidemiological and diagnostic classification criterion, but should not be used in isolation, with other circumstances having to be taken into account such as age, rapidity of bone loss or the frequency of falls , since BMD only explains 70% of bone fragility .
Introduction. Osteoporosis. Its importance
La Osteoporosis is a disease which does not have a totally satisfactory definition . Since the 50s, when Fuller Albright defined it as “too little bone” , an incomplete concept, since it only recognises the quantitative, and not the qualitative aspect of the disease, it has been succeeded by other definitions, such as that of the American National Institute of Health (NIH) which in 1988 referred to osteoporosis as “a condition in which bone mass is reduced, increasing the bone’s susceptibility to suffer fractures” [2,3], or that agreed by the Hong Kong Consensus in 1993 . In spite of it not being totally satisfactory, nowadays we accept the definition published by the NIH in the year 2001, an update of the 1988 version, which considers osteoporosis to be “a disease of the whole skeleton characterised by low bone mass and an alteration in bone microarchitecture which causes bone fragility, with a consequent increase in the risk of fractures” .