Sullivan TR, Yelland LN, Gibson RA, Thakkar SK, Huang F, Best KP, Devaraj S, Zolezzi IS, Makrides M. Predictors of compliance with higher dose omega-3 fatty acid supplementation during pregnancy and implications for the risk of prematurity: exploratory analysis of the ORIP randomised trial.
BMJ Open 2023;
13:e076507. [PMID:
37739459 PMCID:
PMC10533701 DOI:
10.1136/bmjopen-2023-076507]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/05/2023] [Indexed: 09/24/2023] Open
Abstract
BACKGROUND
Intention-to-treat analyses of the Omega-3 to Reduce the Incidence of Prematurity (ORIP) trial found that omega-3 (n-3) fatty acid supplementation reduces the risk of prematurity in the subgroup of women with a singleton pregnancy and low n-3 status early in pregnancy, but not overall. However, results may have been influenced by less-than-optimal compliance.
OBJECTIVES
To identify predictors of compliance with n-3 supplementation and determine treatment effects among compliers.
DESIGN
Exploratory analyses of a multicentre-blinded randomised trial.
SETTING
6 tertiary care centres in Australia.
PARTICIPANTS
5328 singleton pregnancies.
INTERVENTIONS
Daily capsules containing 900 mg n-3 long-chain polyunsaturated fatty acids or vegetable oil, consumed from before 20 weeks gestation until 34 weeks gestation.
OUTCOME MEASURES
Early preterm (<34 weeks gestation) and preterm birth (<37 weeks gestation). Women were considered compliant if they reported missing less than a third of their allocated capsules in the previous week during a mid-pregnancy appointment.
RESULTS
Among 2654 singleton pregnancies in the n-3 intervention group, 1727 (65%) were deemed compliant with supplementation. Maternal characteristics associated with compliance included age, years of full-time education, consuming alcohol but not smoking in the 3 months leading up to pregnancy, fewer previous births and taking dietary supplements at enrolment. Based on complier average causal effects, n-3 supplementation reduced the risk of preterm birth in compliers (relative risk=0.76; 95% CI 0.60 to 0.97), but not early preterm birth (relative risk=0.80; 95% CI 0.44 to 1.46). Consistent with intention-to-treat analyses, the lack of an overall effect on early preterm birth in compliers appeared to be due to beneficial effects in women with low n-3 status at enrolment but not women with replete status.
CONCLUSIONS
Results in compliers were similar to those from intention-to-treat analyses, suggesting that non-compliance was not a major factor in explaining outcomes from the ORIP trial.
TRIAL REGISTRATION NUMBER
ACTRN12613001142729.
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