Effective prevention of cardiovascular disease and diabetes-related events with atorvastatin in Japanese elderly patients with type 2 diabetes mellitus: Adjusting for treatment changes using a marginal structural proportional hazards model and a rank-preserving structural failure time model

Geriatrics and Gerontology International, 03/26/2012

Shinozaki T et al. - The use of atorvastatin to lower cholesterol levels in elderly Japanese patients with type 2 diabetes mellitus appears to reduce the risk of cardiovascular and diabetes-related events.

Methods

  • Data were obtained from 1173 patients aged 65–84 years who were enrolled in the J–EDIT.
  • Patients were followed prospectively for 6 years to determine the effects of atorvastatin on serum cholesterol levels, and cardiovascular and diabetes–related events.
  • Because the study protocol allowed atorvastatin to be prescribed according to the clinical needs of each patient, the authors regarded the J–EDIT data as if they came from a cohort study.
  • The authors adjusted for clinical characteristics during the study as time–dependent confounders using two methods, inverse–probability–of–treatment (IPT) weighting and g–estimation method.
  • The total follow–up period was 5310.8 person–years (5.7 years of median follow up), during which 202 patients received atorvastatin treatment.
  • Atorvastatin was associated with moderate reductions in cholesterol levels: 24.2 mg/dL for total cholesterol, 22.9 mg/dL for low–density lipoprotein (LDL) cholesterol and 24.3 mg/dL for non–high–density lipoprotein cholesterol at the first post–treatment year.

Results

  • As a result, the proportion of patients who achieved targeted levels of LDL cholesterol clearly increased after atorvastatin treatment.
  • Eight patients in 476.6 person–years among atorvastatin–treated and 113 untreated patients in 4721.4 person–years had cardiovascular events (the composite end–point of fatal/non–fatal myocardial infarction, angina pectoris, coronary intervention, and fatal/non–fatal cerebrovascular disease); hazard ratio (HR) = 0.48, 95% confidence interval (CI) = 0.19–1.16, P = 0.10, and HR = 0.32, 95% CI = 0.05–1.87, P = 0.21 from IPT weighting and g–estimation method, respectively.
  • Furthermore, seven in 475.0 person–years among atorvastatin–treated and 149 untreated patients in 4682.4 person–years had diabetes–related events (the composite end–point of sudden death, renal failure death, death as a result of hyperglycemia or hypoglycemia, diabetic gangrene and congestive heart failure in addition to cardiovascular event); HR = 0.30, 95% CI = 0.12–0.77, P = 0.01, and HR = 0.40, 95% CI = 0.09–0.89, P = 0.03 from IPT weighting and g–estimation method, respectively.
  • When cardiovascular events were further differentiated into coronary vascular and cerebrovascular events, atorvastatin especially decreased the cerebrovascular risk.

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