In vitro fertilisation (IVF) or Intra-cytoplasmic sperm injection (ICSI) : Which is better?

Overview

In Vitro Fertilisation (IVF) and Intracytoplasmic Sperm Injection (ICSI) are two of the most common fertility treatments. The main difference between IVF and ICSI is how the sperm fertilises the egg. In IVF, the egg and sperm are left to fertilise on their own. In ICSI, one sperm is directly injected into the egg. Currently, ICSI is the treatment of choice for couples with male factor infertility or with previous low fertilisation rates. An “ICSI for all” approach has been suggested as the treatment of choice in all cases requiring assisted conception. However, previous studies comparing IVF and ICSI have shown inconsistent results. The well-known fertility clinical apprached us to provide them solid statistical evidence of which treatment is superior in different patient types

Challenges

• large dataset
• The statistical findings should be interpretable to lay-audience
• The assumption of statistical model needs to be met in order to provide unbiased, valid conclusion

Statistical approach

We used generalised linear model (GLM) with Poisson distributed errors to model the number of events (and rates). We reported results from both unadjusted(crude) and adjusted models. The models for live birth rate and clinical pregnancy rate were adjusted for age of female, number of embryos transferred and day of embryo transfer. The models for implantation rate and live birth per embryo transfer were only adjusted for number of live births and number of embryos transferred. The models for fertilisation rate and miscarriage rate were adjusted for age. The overdispersion in the model if present, has been corrected by estimating model parameters by quasi-likelihood. We used robust standard errors in each model. The goodness of fit of the model was assessed via residuals and fitted values plots and residual deviance test.

We have used linear regression model to evaluate whether success rate of both treatments was significantly different over time.

Outcome:

The project completed on time with detailed report explaining statistical methods and findings in non-technical language. Multivariate model after adjusting of covarites provided an evidence that ICSI ,compared to conventional IVF is associated with lower implantation, clinical pregnancy and live birth rates in women undergoing their first treatment cycle. These findings where consistent in cycles with and without male-infertility, across different age groups and different time periods.