Evidence-based medicine for treatment: an in vitro fertilization trial

Evidence-based evaluation of treatment is a pivotal component of an effective and satisfying clinical practice. When the best evidence has been identified, it can be efficiently assessed on three levels: Are the methods valid? Is the effect sufficiently large to be meaningful to patients? Are the patients, intervention(s), and outcomes studied applicable to our own patients? These criteria were applied to a multicenter trial that evaluated whether intracytoplasmic sperm injection (ICSI) was superior to in vitro fertilization (IVF) among infertile couples with no known male factor who were on a waiting list for IVF. The study was a well-designed randomized controlled trial that effectively concealed the randomization list and took reasonable steps to exclude bias. The results seemed important because the number needed to treat (13) was relatively low and significant, but the primary outcome (implantation rate) was not clinically meaningful. The trial results would have been relevant to most infertile couples with no known male factor if it had been powered to evaluate a difference in a more relevant clinical outcome, such as live birth. Thus, it has not been shown definitively that ICSI is inferior to IVF among couples with no known male factor, and clinical demand for ICSI may continue to rise.