Can the New Zealand antenatal scoring system be applied in the United Kingdom?

Abstract

We aimed to assess the sensitivity and predictive values of using Knox scoring in the United Kingdom, in order to reduce unnecessary hospital referral. One hundred and sixty-six pregnant women were assessed at booking by the current antenatal scoring as well as by Knox scoring and then the same women were reassessed at 36 weeks' gestation. At booking Knox scored 11.7% of women as high risk while the current antenatal system scored 48.9%. At 36 weeks' gestation Knox scored 1.4% of the same pregnant women as high-risk when our scoring system identified 37.9% as high-risk women. We had one case of perinatal death and nine cases of perinatal morbidity. Knox scoring showed a higher positive predictive value (17.6% vs. 12.1%) but less sensitivity (30% vs. 90%) than the current scoring system. That will lead to dramatic reduction of hospital referral at the booking visit from 48.9% to 11.7% and late in pregnancy from 37.9% to 1.4%.

High-risk pregnancies and their association with severe maternal morbidity in Nepal: A prospective cohort study

“…A study conducted in 2002 in the United Kingdom compared the Knox scoring system to the Chard et al risk scoring system. The prevalence of high-risk pregnancies on admission for the Knox scoring system was 11.7% vs. 48.9% for the Chard et al risk scoring system, and at 36 weeks' gestation, the prevalence using the same two systems was 1.4% vs. 38%, respectively [39]. The prevalence of high-risk pregnancies in New Zealand was 16% in 1993 [40] and 37% in 1990 [41]; the first study used the Knox scoring system while the second used a self-developed scoring system.…”

“…First, the diagnostic criteria are sensitive to the presence of even a single risk factor, which affects the overall sensitivity of the tools. Second, the predictive accuracy of the scoring system depends on the burden of outcomes, such as very high fertility rates in the population [39].…”