One more time CNAMTS boys have crunched the numbers from the reimbursement data bases.
They previously had done this exercise in real life for the mediator and they had found cardiac side effects. This time they investigated a new category of blood thinner the NACOs (Nouveaux Anti Coagulants). Unlike the mediator they have concluded that in the short term (3 months) no evidence of any adverse side effects such as bleeding or thrombosis could be found.
The mediator study:
The NACOS study of the risk associated with the initiation of treatment with the new blood thinner in anticoagulant treatment naive patients (3 months of follow up):
The NACOS study of the risk associated with the change in treatment consisting in replacing Warfarin by the new blood thinner in anticoagulant treatment experienced patients (4 months of follow up):
Historic cohort study, generally means to take a look back at events that already have taken place.
database (Photo credit: Sean MacEntee)
With the huge data bases containing Millions of lines of historic of several years of reimbursements of health care and health conditions now at the disposal of nation wide health care insurances like CNAMTS or RSI in France or Kaiser Permanente or Veteran Affairs in the USA , historical cohorts such as the one that is described in the article referenced below are very easy to implement provided that researchers have access to the data base and use the appropriate software to extract accurately the information to transform rough data in a relevant medical information. Personally I am a fan of SAS enterprise guide (no funding by SAS to disclose for this Blog).
But nothing being perfect in this world the weakness of such historical cohorts retrospectively rebuilt is that they can only put in evidence associations without absolutely no hint but the possible causation process involved in the association. Their force is of course the number of subjects analyzed (usually huge) and the provenance of the subjects (community and real life subjects as opposed as the carefully selected subjects of the controlled randomized trials).
But at the end of the day, to conclude like the study referenced below does, that high doses of ACE treatment causes a lowering of the mortality rate and the readmission rate is obviously going beyond the proper results of the study. Indeed no observational historic cohort, whatever the size of the analysed sample is, has the power to demonstrate a causality link. One possible explanation of the association unveiled by the study is that prescribers could be more reluctant to give high doses of ACE to the more fragile groups and comorbidity incurring groups of the studied population.
More content and referenced study:
ARCH INTERN MED PUBLISHED ONLINE JULY 2, 2012 WWW.ARCHINTERNMED.COM
Improved Outcomes in Heart Failure Treated With High-Dose ACE Inhibitors and ARBs: A Population-Based Study: full text research letter