Correspondence (letter to the editor): Helpful or Harmful?

I would like to thank the authors for this very important study (1). Nevertheless, I see the results less positively than the authors, as the screening guidelines are not followed in about one-third of participants who need further testing. Of the women who were given the pre-test, 12.7% also underwent the diagnostic test (i.e., oGTT) in case of a result defined as pathological—according to the guideline of the screening program. Yet 4.8% only received the diagnostic test. Thus, one-third of women needing further testing do not receive the care defined in the guideline (4.8% of 17.5% woman with further testing). But screenings are designed in a way that a defined optimum between harm and benefit will be achieved when following a predetermined diagnostic test. In this case, stepwise testing is required: first, the pre-test; then, if the results are abnormal, the diagnostic test. Not adhering to this process, and only performing the diagnostic test, can lead to incalculable shifts between benefit and harm—and this happened for almost one-third of pregnant women who were defined as having gestational diabetes.

Now, it could be argued that it does not matter anyway as the screening is not based on evidence from clinical studies (2)—which is always expected for screenings today; rather, all knowledge about thresholds of test-values or benefits stem from only five, mostly very small therapy-studies. Thus, the question about the thresholds, and therefore who should or should not be treated, cannot be answered based on screening-studies. Nevertheless, mistakes that have already been made, and that are potentially dangerous for pregnant women, should not be further complimented by arbitrary performing. This is especially true for a screening for which the benefit, which cannot be clearly put into numbers, but—unlike in women with manifest diabetes—has to be extremely small (3, 4).