Hello everyone! We are planning a study to determine the impact of the diagnosis of breast cancer on female sexual dysfunction. Estimated prevalence for sexual dysfunction among non-breast cancer Brazilian women is 40%. Estimated prevalence of sexual dysfunction among Brazilian breast cancer patients is 65%. We will evaluate prevalence in several different time points: T0, T6 months (m), T12m, T24m, T36m, T48m, and T60m. Applying STATA's two-sample paired-proportions test using alpha at 0.05 and power at 0.8, as well as the above mentioned estimated prevalences, we got n=37. However, we are planning to evaluate several different variables that might be associated with the expected decrement in sexual quality of life of these women through 5 years of follow-up. How can I adjust the n to keep the study power? We thought of adding another 37 patients for each of the expected 10 variables we expect to go on the multivariate analysis, giving us a total of 370 women. Does it make sense?