Focus on Alternative and Complementary Therapies
www.pharmpress.com/fact
Focus Alternat Complement Ther©2005 Pharmaceutical Press
Focus Altern Complement Ther 2003; 8: 157
Iscador, a standardised mistletoe extract, is used as complementary medicine in the treatment of cancer. To prove efficacy and safety in the treatment of early stage breast cancer, a retrolective pharmacoepidemiological cohort study was performed. The concept of retrolective cohort studies and the adjustment for inhomogeneities between treatment groups with propensity score are explained and demonstrated with the data of the study.
In 16 centres the postoperative data of a cohort of more than 1442 patients with primary breast cancer, treated either with Iscador as the complementary medicine or without complementary medicine, were extracted from the patient files on CRFs and analysed for efficacy and safety. The data quality was supervised by independent monitors and checked by audits. The main problem in efficacy analysis is the inhomogeneity of treatment groups in centres and baseline characteristics. To evaluate the influence of these characteristics on treatment assignment, the propensity score (i.e. the probability of complementary treatment as a function of the characteristics) was calculated. This score was used to adjust the outcome (overall survival, disease-free survival) to comparable conditions and to obtain an unbiased treatment comparison.
Characteristics of the centres showed the most relevant influence on complementary treatment in the study. The outcome also differed highly between centres. By adjustment to homogeneous conditions, an unbiased treatment comparison was possible and showed efficacy of the complementary treatment.
Retrolective cohort studies and adjustment with the propensity score enable valid treatment comparisons of therapeutic efficacy and safety for complementary medicine.
