Strengths and limitations
The strengths of this study are inclusion of a large cohort of pregnancies with retrospective application of the FMF algorithm. This allowed for the input of actual data, such as physician compliance with aspirin prophylaxis, into the model structure and probabilities for the cost analysis.
Due to the retrospective application of the FMF algorithm, a proportion of those who were screen positive using the FMF algorithm received aspirin. Therefore, a limitation of this study was that the input data had to be estimated in this group adjusting for the possible effect of aspirin. However, as we have only considered the effect of the intervention on preterm, rather than total PE, of which a possible benefit has been demonstrated22, our estimates of cost-savings can only represent an under-estimate.
Finally, neither PLGF or UtA-PI were incorporated into the FMF algorithm in our study. Through clinical effectiveness studies, incorporation of these biomarkers would only improve the performance of the screening method and, therefore, an even greater reduction in the rate of preterm PE could be anticipated. Again, this emphasises the conservative approach adopted in this study to avoid an inflation in the expected cost-savings.8, 23