The Korean Journal of Medicine

The Korean Association of Internal Medicine (대한내과학회)
권호 표지

LDL cholesterols levels after statin treatment: A comparison of measured vs. estimated values

Statin 치료시 LDL 콜레스테롤의 직접 측정값과 계산값의 비교

  • Kim, Hyeon-Jin (Department of Internal Medicine, Maryknoll Medical Center) ;
  • Suk, Ji-Hye (Department of Internal Medicine, Maryknoll Medical Center) ;
  • Kang, Ji-Hyun (Department of Internal Medicine, Maryknoll Medical Center) ;
  • Kwon, Hyuk-Yong (Department of Internal Medicine, Maryknoll Medical Center) ;
  • Hwang, Chi-Sung (Department of Internal Medicine, Maryknoll Medical Center) ;
  • Kim, Myoung-Joon (Department of Internal Medicine, Maryknoll Medical Center) ;
  • Kim, Mi-Kyung (Department of Internal Medicine, Maryknoll Medical Center) ;
  • Kim, Tae-Ik (Department of Internal Medicine, Maryknoll Medical Center) ;
  • Kim, In-Joo (Department of Internal Medicine, Pusan National University School of Medicine)
  • Received : 2010.05.04
  • Accepted : 2010.07.07
  • Published : 2010.09.01
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Abstract

Background/Aims: Lowering low-density lipoprotein cholesterol (LDL-C) is the primary target for the prevention of cardiovascular disease. Previous studies have shown that estimated LDL-C levels calculated using Friedewald's formula (FLDL-C) are closely correlated with directly measured LDL-C levels (DLDL-C). However, because statins not only reduce LDL-C, but also alter the levels of parameters used to calculate FLDL-C (i.e., total cholesterol, triglycerides, and high-density lipoprotein cholesterol), whether calculated LDL-C levels remain a reliable estimate of actual levels after statin treatment is unclear. Methods: Subjects included 985 patients at high risk of cardiovascular disease who had taken statins for more than 6 months. FLDL-C data were compared to DLDL-C data. Results: A strong correlation was observed between DLDL-C and FLDL-C data ($R^2$=0.879). However, the absolute values for FLDL-C and DLDL-C differed significantly according to a paired t-test, and 42.3% of patients showed a difference of greater than 10% between these two values. Among patients with diabetes, the percentage of patients deemed to have achieved target LDL-C levels differed significantly according to the method of LDL-C determination (p=0.007). Conclusions: FLDL-C and DLDL-C data remained well correlated after statin treatment, although the absolute values differed significantly according to the LDL-C determination method. Furthermore, the percentage of subjects deemed to achieve target LDL-C levels differed significantly according to the method of determination among patients with diabetes.

목적: LDL 콜레스테롤의 수치를 적정 수준으로 조절하는 것이 고지혈증에 의한 심혈관계 질환의 1차적 혹은 2차적 예방에 매우 효과적이다. Statin의 사용은 일차적으로 LDL 콜레스테롤의 감소를 목표로 하지만, Friedewald 공식에 이용되는 세 가지 변수인 총 콜레스테롤, 중성지방과 HDL 콜레스테롤의 변화도 관찰된다. 이제까지 직접측정법과 Friedewald 공식에 의한 계산법을 비교한 연구들에서는 statin 치료를 고려해서 분석하지 않았으므로 기존의 연구 결과가 statin을 사용한 후에도 적용될 수 있을지는 아직 알 수 없다. 이에 우리는 statin 치료 후에 Friedewald 공식에 따른 계산값을 직접 측정법으로 측정한 LDL 콜레스테롤 결과와 비교하여 그 차이를 분석하고자 하였다. 방법: 메리놀병원 내분비내과와 심장내과 진료를 받고 있는 환자들 중에서 적어도 6개월 이상 statin을 복용한 985명의 심혈관 질환 고위험군인 환자들을 대상으로 연구하였다. 총 콜레스테롤, 중성지방, HDL 콜레스테롤 측정치를 이용한 Friedewald 공식으로 계산된 LDL 콜레스테롤 수치를 직접 측정한 LDL 콜레스테롤 수치와 비교하였다. 결과: Statin 치료 후 DLDL-C은 $80.5{\pm}21.3$ mg/dL이었고, FLDL-C은 $82.1{\pm}23.3$ mg/dL이었다. 두 수치를 비교하였을 때, 전반적인 상관관계는 양호하였으나($R^2$=0.879) paired t-test 상에서 두 값의 차이는 통계적으로 유의하였고, 실제 42% 이상의 환자에서 $%{\Delta}LDL$이 ${\pm}10%$ 이상이었다. 계산값과 직접 측정값을 당뇨병 환자의 LDL 콜레스테롤의 치료 목표인 100 mg/dL을 기준으로 목표 도달률을 비교하였을 때, 비당뇨병군에서는 통계학적으로 유의한 차이가 없었지만(p=0.132), 당뇨병군에서는 통계학적으로 유의한 차이가 있었다(p=0.007). 결론: Statin 치료 후 Friedewald 공식으로 계산한 LDL 콜레스테롤과 직접 측정한 LDL 콜레스테롤 수치는 비교적 좋은 연관성을 보였으나, 각각의 수치의 비교에서는 의미 있는 차이를 보였다. 특히 당뇨병군의 치료효과 판정에서는 유의한 차이가 있었다. 향후 statin 치료의 적정성을 평가하거나 치료 변경 여부를 결정하는 경우에 Friedewald 공식에 의한 계산값과 LDL 콜레스테롤의 직접측정법의 비교에 대해서 추가적인 연구가 뒷받침되어야 할 것으로 생각된다.

Keywords

References

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