Objectives: To identify a national, population-based cohort of women with AFLP, to evaluate proposed diagnostic criteria and to document accurately the incidence, management and outcomes of the condition.
Design: A population-based descriptive study using the UK Obstetric Surveillance System.
Setting: All 229 hospitals with consultant-led maternity units in the UK.
Participants: 57 women in the UK diagnosed with AFLP between February 2005 and August 2006 in an estimated cohort of 1,132,964 maternities.
Main outcome measures: Rates with 95% confidence intervals (95%CI).
Results: The estimated incidence of AFLP was 5.0 cases per 100,000 maternities (95%CI 3.8-6.5/100,000). Fifty-five cases (90%) were confirmed by diagnostic criteria and clinical assessment, 2 (3%) by clinical assessment alone, representing 97% agreement (kappa statistic=0.78). 18% of women had twin pregnancies and 20% were underweight (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 0-9.4%). There were seven deaths among 67 infants (perinatal mortality rate 104 per 1000 births, 95%CI 43-203).
Conclusions: We have identified the largest population-based cohort of women with AFLP to date. 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.