A prospective national study of acute fatty liver of pregnancy in the UK
- 1National Perinatal Epidemiology Unit, University of Oxford, UK
- 2Guys and St Thomas’ Hospitals NHS Foundation Trust, London, UK
- Dr M Knight, National Perinatal Epidemiology Unit, University of Oxford, Old Road Campus, Oxford OX3 7LF, UK;
- Revised 25 February 2008
- Accepted 29 February 2008
- Published Online First 10 March 2008
Objectives: To identify a national, population-based cohort of women with acute fatty liver of pregnancy (AFLP), to evaluate proposed diagnostic criteria and to document accurately the incidence, management and outcomes of the condition.
Subjects and methods: This was a population-based descriptive study using the UK Obstetric Surveillance System, carried out in all 229 hospitals with consultant-led maternity units in the UK. The participants comprised 57 women in the UK diagnosed with AFLP between February 2005 and August 2006 in an estimated cohort of 1 132 964 maternities (women delivering).
Results: The estimated incidence of AFLP was 5.0 cases per 100 000 maternities (95% CI 3.8 to 6.5 per 100 000). Fifty-five cases (90%) were confirmed by diagnostic criteria and clinical assessment, two (3%) by clinical assessment alone, representing 97% agreement (kappa statistic = 0.78). 18% of women had twin pregnancies and 20% were underweight (body mass index (BMI) <20). 60% of women were admitted to intensive care and 15% to a specialist liver unit. One woman received a liver transplant. One woman died (case fatality rate 1.8%, 95% CI 0% to 9.4%). There were seven deaths among 67 infants (perinatal mortality rate 104 per 1000 births, 95% CI 43 to 203).
Conclusions: The largest population-based cohort of women with AFLP to date has been identified. Diagnostic criteria previously proposed agree substantially with clinical diagnosis. The incidence estimate from this study is lower than documented by earlier hospital-based studies, but maternal and neonatal outcomes are better than previously reported, possibly related to improved ascertainment. Women with twin pregnancies appear to be at higher risk, but further studies are needed to investigate the risk associated with low BMI.
MK designed the study, coordinated data collection, coded the data, carried out the analysis and wrote the first draft of the paper. CNP provided clinical input to the study and contributed to the analysis and writing of the paper. JJK assisted with the design of the study, supervised the data collection and analysis, and contributed to writing the paper. PS assisted with data coding, and conducted validation of the data and some analysis. PB had the original idea for the surveillance system, provided advice at every stage of the study and contributed to the writing and editing of the paper. PB will act as study guarantor.
Funding: MK is funded by the National Coordinating Centre for Research Capacity Development of the Department of Health. JJK was partially funded by a National Public Health Career Scientist Award from the Department of Health and NHS R&D (PHCS022). The National Perinatal Epidemiology Unit is funded by the Department of Health in England. The views expressed in this paper are those of the authors and do not necessarily reflect the views of the Department of Health
Competing interests: None.
The UKOSS general methodology (04/MRE02/45) and this study (04/MRE02/71) were approved by the London Multicentre Research Ethics Committee.