Advice

Clinical and technical evidence

Clinical and technical evidence

A literature search was carried out for this briefing in accordance with the interim process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting mibs@nice.org.uk.

Published evidence

Six studies are summarised in this briefing, including a total of 487 people.

Three studies used the Novii Wireless Patch System and 3 studies used the AN24 device by Monica Healthcare. The Novii Wireless Patch System is a different product to AN24 but is based on the same technology and uses the same number and positioning of electrodes. Novii Wireless Patch System has an improved design that makes it easier to use, wireless and more comfortable, and gives greater control over electrode positioning. The Novii Wireless Patch System also features additional monitoring channels and improved monitoring of fetal heart rate (FHR), maternal heart rate (MHR) and uterine contractions.

Two studies were reported in abstract format only and so are limited in detail. One study is a randomised controlled trial (RCT) comparing Novii with doppler standard external monitoring (SEM), with 2 secondary analyses after this RCT. Two studies are non-comparative single arm studies and 1 study compared AN24 with a diffuse electrode array. Three of the studies included women with body mass indexes (BMIs) over 30 kg/m2 and the results support the company's claim that the technology is effective in these women. There are further studies not summarised here: 3 published studies and 2 conference abstracts on AN24 (Cohen et al. 2012; Hayes-Gill et al. 2012; Hayes-Gill et al. 2019; Durosier et al. 2013; Geraldes et al. 2015). One study concluded that electrohysterographic technique (AN24) was more reliable and similar in accuracy to tocodynamometry in detecting intrapartum uterine contractions (Hayes-Gill et al. 2012).

The clinical evidence and its strengths and limitations is summarised in the overall assessment of the evidence.

Overall assessment of the evidence

The evidence for the technology is of low to moderate methodological quality, and most of the studies are small in terms of patient numbers. One study was partially done in the UK, but it is not clear if it was an NHS setting. The comparators chosen for the studies represent standard care in the NHS. The evidence shows that the technology is at least equivalent to standard care, is more effective in people with high BMIs (over 30 kg/m2) and reduces MHR and FHR confusion during second stage labour.

Monson et al. (2020a)

Study size, design and location

RCT of 218 women in labour in the US.

Intervention and comparator

Novii Wireless Patch System compared with FHR SEM.

Key outcomes

Device setup failure occurred more often in the fetal electrocardiography (fECG) group (8 of 107 [7.5%] compared with 0 of 109 [0%] for SEM). There was no difference in the percentage of interpretable tracing between the 2 groups. However, fECG produced more interpretable FHR tracing in subjects with a BMI of 30 kg/m2 or more. When considering the percentage of interpretable minutes of FHR tracing while on study device only, fECG outperformed SEM for all subjects, regardless of maternal BMI. Maternal demographics and clinical outcomes were similar between arms. In the fECG group, there were more device changes compared with SEM (51% compared with 39%), but there were fewer nursing device adjustments (2.9 compared with 6.2 mean adjustments intrapartum; p<0.01). There were no differences in physician device satisfaction scores between groups, but fECG generated higher patient satisfaction scores.

Strengths and limitations

This study adds to the very limited data available on comparing new FHR monitoring to SEM using a RCT design. It shows that fECG performed similarly to SEM, generated higher patient satisfaction rates and may be particularly useful in patients with a BMI over 30 kg/m2. Obvious differences in the devices' appearances limited blinding, which may have led to provider, nurse and patient bias.

Monson et al. (2020b)

Intervention and comparator

Novii Wireless Patch System compared with standard external FHR monitoring.

Key outcomes

A regression model Akaike information criteria (AIC) plot identified 31 kg/m2 as the ideal BMI cut-off point for fECG device performance. At this point, fECG gave consistently more interpretable 10‑minute FHR tracing segments compared with SEM. For the 1‑minute FHR tracing analysis, an even lower BMI cut-off point of 25 kg/m2 was identified based on AIC estimates. At a BMI of 25 kg/m2, fECG gave a higher proportion of interpretable minutes of FHR tracing compared with SEM.

Strengths and limitations

This study shows that fECG consistently generated more interpretable 10‑minute and 1‑minute FHR tracing segments compared with SEM in women with BMIs over 31 kg/m2 and 25 kg/m2, respectively. Women with BMIs over 31 kg/m2 may benefit from fECG device in labour. This study is based on the same group of patients included in Monson et al. (2020a). This study is reported in abstract form only and therefore is limited in detail.

Monson et al. (2020c)

Intervention and comparator

Novii Wireless Patch System compared with SEM.

Key outcomes

Maternal demographics and clinical outcomes were similar between arms. fECG generated significantly more interpretable 10‑minute segment FHR data in the second stage of labour. fECG use resulted in almost double the amount of interpretable 10‑minute FHR tracing segments compared with SEM. Similar findings were noted in the 1‑minute segment FHR tracing analysis.

Strengths and limitations

This study highlights the clinical utility of fECG, particularly during the second stage of labour, when FHR tracing signal quality is often compromised. This study is based on the same group of women included in Monson et al. (2020a). This study is reported in abstract form only and so is limited in detail.

Graatsma et al. (2010)

Intervention and comparator

AN24 (Monica Healthcare).

Key outcomes

Participants' BMI ranged from 16.0 kg/m2 to 50.7 kg/m2 (median 26.9 kg/m2). The correlation coefficient between BMI and recording quality was -0.35 (95% confidence interval [CI] -0.60 to -0.03) for the gestational age group 20 weeks to 25 weeks plus 6 days, -0.08 (95% CI -0.28 to 0.13) for the 26 weeks to 33 weeks plus 6 days group, and -0.20 (95% CI -0.40 to 0.03) for the 34 weeks or more group. Median recording quality in participants with BMIs of 30 kg/m2 or more in each gestational age group was 97.4%, 98.9%, and 100%, respectively. BMI has no clinically significant influence on FHR recording quality using fECG. It can therefore be considered a good method for monitoring the condition of the baby in pregnancies of women who are obese.

Strengths and limitations

AN24 is a previous version of Novii Wireless Patch System. This study shows that AN24 is effective for monitoring in pregnant women with a range of BMIs, including those with a BMI of 30 kg/m2 and over who would be classified as obese or severely obese. The evidence is based on pregnant women who were not in labour. The results should be interpreted with caution and further research is needed to determine the effect on women in labour.

Hill et al. (2014)

Intervention and comparator

AN24 (Monica Healthcare) and a diffuse electrode array.

Key outcomes

Success rates for AN24 and the comparator were nearly identical (98.5% plus or minus 1.9% compared with 98.4% plus or minus 1.9%, respectively; p=0.879). The overall positive percent agreement of AN24 and the comparator was 94.7% plus or minus 3.8%. AN24 was as accurate as the comparator. The overall root-mean-square error of the Bland-Altman regression line was 5.5 beats per minute (bpm) plus or minus 2.4 bpm. Mean overall bias was near 0 (-0.004 bpm plus or minus 0.416 bpm). No measurements were affected by labour stage or BMI.

Strengths and limitations

AN24 is a previous version of the Novii Wireless Patch System. Part of the study was done in the UK so the setting may be more representative of NHS practice. This study shows that the AN24 is equivalent to a diffuse electrode array. One of the authors of the study is an employee of Monica Healthcare.

Stampalija et al. (2012)

Intervention and comparator

AN24 (Monica Healthcare) and doppler telemetry.

Key outcomes

The overall success rate for FHR monitoring was similar between trans-abdominal ECG and doppler telemetry (88.5% plus or minus 16.7% compared with 89.4% plus or minus 7.6%), except for the second stage of labour. A significantly higher rate of FHR and MHR confusion (p<0.001) was found for doppler telemetry (4.5% plus or minus 4.5%) compared with trans-abdominal ECG (1.3% plus or minus 1.9%), especially in the second stage of labour and during maternal movements.

Strengths and limitations

AN24 is a previous version of Novii Wireless Patch System. This study shows that trans-abdominal ECG monitoring is feasible, with comparable success rate to traditional doppler telemetry, without interfering with maternal mobility or requiring midwife intervention. Furthermore, the reduction in MHR and FHR confusion from trans-abdominal ECG could reduce obstetric interpretation errors.

Recent and ongoing studies