Ondansetron and metoclopramide as second-line antiemetics in women with nausea and vomiting in pregnancy: the EMPOWER pilot factorial RCT

Robson, Stephen, McParlin, Catherine, Mossop, Helen, Lie, Mabel, Fernandez-Garcia, Cristina, Howel, Denise, Graham, Ruth, Ternent, Laura, Steel, Alison, Goudie, Nicola, Nadeem, Afnan, Phillipson, Julia, Shehmar, Manjeet, Simpson, Nigel, Tuffnell, Derek, Campbell, Ian, Williams, Rew, O’Hara, Margaret E, McColl, Elaine and Nelson-Piercy, Catherine (2021) Ondansetron and metoclopramide as second-line antiemetics in women with nausea and vomiting in pregnancy: the EMPOWER pilot factorial RCT. Health Technology Assessment, 25 (63). pp. 1-116. ISSN 1366-5278

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Abstract

Background
Around one-third of pregnant women suffer from moderate to severe nausea and vomiting, causing physical and emotional distress and reducing their quality of life. There is no cure for nausea and vomiting in pregnancy. Management focuses on relieving symptoms and preventing morbidity, and often requires antiemetic therapy. National guidelines make recommendations about first-, second- and third-line antiemetic therapies, although care varies in different hospitals and women report feeling unsupported, dissatisfied and depressed.

Objectives
To determine whether or not, in addition to intravenous rehydration, ondansetron compared with no ondansetron and metoclopramide compared with no metoclopramide reduced the rate of treatment failure up to 10 days after drug initiation; improved symptom severity at 2, 5 and 10 days after drug initiation; improved quality of life at 10 days after drug initiation; and had an acceptable side effect and safety profile. To estimate the incremental cost per treatment failure avoided and the net monetary benefits from the perspectives of the NHS and women.

Design
This was a multicentre, double-dummy, randomised, double-blinded, dummy-controlled 2 × 2 factorial trial (with an internal pilot phase), with qualitative and health economic evaluations.

Participants
Thirty-three patients (who were < 17 weeks pregnant and who attended hospital with nausea and vomiting after little or no improvement with first-line antiemetic medication) who attended 12 secondary care NHS trusts in England, 22 health-care professionals and 21 women participated in the qualitative evaluation.

Interventions
Participants were randomly allocated to one of four treatment groups (1 : 1 : 1: 1 ratio): (1) metoclopramide and dummy ondansetron; (2) ondansetron and dummy metoclopramide; (3) metoclopramide and ondansetron; or (4) double dummy. Trial medication was initially given intravenously and then continued orally once women were able to tolerate oral fluids for a maximum of 10 days of treatment.

Main outcome measures
The primary end point was the number of participants who experienced treatment failure, which was defined as the need for further treatment because symptoms had worsened between 12 hours and 10 days post treatment. The main economic outcomes were incremental cost per additional successful treatment and incremental net benefit.

Results
Of the 592 patients screened, 122 were considered eligible and 33 were recruited into the internal pilot (metoclopramide and dummy ondansetron, n = 8; ondansetron and dummy metoclopramide, n = 8; metoclopramide and ondansetron, n = 8; double dummy, n = 9). Owing to slow recruitment, the trial did not progress beyond the pilot. Fifteen out of 30 evaluable participants experienced treatment failure. No statistical analyses were performed. The main reason for ineligibility was prior treatment with trial drugs, reflecting an unpredicted change in prescribing practice at several points along the care pathway. The qualitative evaluation identified the requirements of the study protocol, in relation to guidelines on anti-sickness drugs, and the diversity of pathways to care as key hurdles to recruitment while the role of research staff was a key enabler. No important adverse events or side effects were reported.

Limitations
The pilot trial failed to achieve the recruitment target owing to unforeseen changes in the provision of care.

Conclusions
The trial was unable to provide evidence to support clinician decisions about the best choice of second-line antiemetic for nausea and vomiting in pregnancy.

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