Efficacy of Statins on BMB or Fracture Risk in Postmenopausal Women

스타틴이 폐경기 여성의 골밀도 혹은 골절위험에 미치는 효과 -보고된 임상연구결과 분석을 중심으로-

There are 3 different hypotheses on how statins may affect bones, through promoting bone formation, inhibiting bone resorption or through anti-inflammatory effect. In the 3 cross-sectional studies above, one showed increase BMD at hip and spine, one showed increase BMD only at mid-forearm and one showed that the risk reduction in fractures is not explained by the changes in BMD however, all 3 studies showed a decrease in risk of fracture associated with statins. In the 2 prospective cohort studies, one showed the use of statins was not associated with BMD at any skeletal site or decreasing the risk of fracture, and the other showed statins except pravastatin decreased in risk of vertebrate fracture but not affecting lumbar spine BMD. All of case-control studies indicated reduction in fracture risk but did not provide any data regarding BMD. 2 of the randomized, controlled studies showed no significant reduction in fracture risk as well as statins' effects on BMD. Finally, one longitudinal study showed statin use reduced fracture risk and increased BMD. Among the conflicting results shown above, even when statin use was shown to increase BMD, it does not seem to account for the reduction in fracture risk. There may be different ways that statins affect bone other than those hypotheses proposed above. Many studies seem to agree that pravastatin does not have any effect on bone. Some studies suggested that the reason statins did not achieve clinically significant increases in BMD in some studies, is due to the low affinity of statins on bone; statins are designed to act in the liver therefore their effective concentration in extrahepatic tissue is low. The limitations to those studies discussed above. Many studies did not account for the change of lifestyle while subjects' were on statins. Increases in weight bearing exercise and changes in diet might affect BMD and thus reduce risk of fractures. Mental alertness and vision acuity might prevent falls from occurring; many statin-users in the studies were young so the risk of fractures from falls would be decreased. Almost all of the studies failed exclude patients with neurological problems. During study periods, many subjects may have been started on drugs for diseases that usually occur with aging which could cause drowsiness and lead to falls. The sample sizes used in some of the trials were small and the duration of treatment and follow up might not have been long enough to see clinically relevant results.

스타틴이 골형성을 자극하며 골밀도를 개선한다는 다수의 동물실험과 임상보고에 의해, 스타틴을 폐경기 이후 노령의 여성 고지혈증 환자에게 골다공증의 예방 혹은 치료적 용도로 사용할 수 있는가에 대한 관심이 고조되어 왔다. 하지만, 보고된 문헌들이 예방 혹은 치료효과를 제시하거나 해석됨에는 아직도 실험결과가 상이하거나 의견이 상충되고 있다. 본 연구는 폐경기 이후의 고지혈증을 지닌 골다공증 환자에게 처방된 스타틴이 실질적으로 골다공증 혹은 골절위험을 경감시키는 예방적 또는 치료적 효과를 지니는지 규명하고자, 1990년부터 2005년 사이에 MEDLINE에 등재된 데이터베이스 중에서 6개의 키워드를 사용하여 인체대상 연구보고서를 cross-sectional study, prospective cohort study 및 case-control study의 연구유형별로 수집, 분류하여 각각의 결과를 비교, 평가하였다. 각 연구결과들은 골다공증 평가에 이용하는 다수의 측정지표들에 대하여 공히 인정될 만한 수준의 유의성 여부를 제공하기에는 곤란했는데, 이는 연구디자인이 부적절했거나 실험대상 환자들이 보유한 각종 질병요소들과 치료상황이 복잡한 상호관계를 지녔기 때문이다. 따라서 대규모의 잘 계획된 이중맹검형 다국가 임상시험을 통해서 임상적 효과 유무가 입증되기 전에는 스타틴을 고지혈증을 보유한 폐경기 이후 노령 여성의 골다공증의 예방 혹은 치료적 용도로 사용하는 것은 아직 시기상조로 사료된다.