Longitudinal Analysis of Serial Liver Biopsies in Chronically Transfused Sickle Cell Disease

Chronic red cell transfusions are commonly used for the treatment and prevention of complications in sickle cell disease (SCD). Liver injury from transfusional iron overload is a recognized morbidity of chronic transfusion therapy, but little is known about the progression of liver injury over time in SCD.

We conducted a retrospective cohort study of all chronically transfused people with SCD who had 2 or more serial liver biopsies at a single academic hospital. Subjects with viral hepatitis were excluded. Serum ferritin, serum ALT, chelation status, and transfusion volumes were extracted from the electronic record and validated against paper records in all subjects. Quantitative liver iron concentration (LIC) was determined at the time of biopsy by inductively coupled plasma-mass spectrometry. Core liver biopsy slides stained for iron and fibrosis were retrieved and scored in a blinded fashion by a hepatopathologist (RA) for total iron score (TIS, Deugnier, 2007) and fibrosis score (Ishak, 1995). Analyses evaluated how liver fibrosis changed over the first 2 biopsies and how changes in biomarkers correlated with changes in fibrosis. Cross sectional analyses assessed the relationship of biomarkers to the presence or absence of fibrosis. Ferritin was analyzed as an average of the 3 closest values ± 6 weeks of liver biopsy. Area under receiver operator characteristic curve (AUC) analysis, likelihood ratios for positive tests (LR+), and summary statistics were calculated using Stata v11.2.

26 people had at least 2 serial core liver biopsies for evaluation (n=70 biopsies total, range 2–7 biopsies per subject). Fibrosis was Ishak grade 0 or 1 in all biopsies. Median age at first biopsy was 13.3 years and median total transfusion duration was 9.4 years. The first 2 biopsies were obtained a median of 2.3 years apart. Evaluation of the first 2 biopsies showed that fibrosis was present in 7/26 initial biopsies and 3/26 second biopsies: fibrosis regressed in 6 subjects, developed in 2 subjects and persisted in 1 subject. Among non-chelated subjects at the time of first biopsy, 2/11 had fibrosis, as compared to 5/15 subjects who had received a mean of 3.7 years of chelation at the time of first biopsy (18% vs 33%, P=0.6). Eleven subjects had 3 or more serial biopsies performed during a median of 9.2 years of chronic transfusion. There was no consistent pattern of fibrosis development, nor was there an apparent association of fibrosis with LIC over time (Figure, asterisks indicate presence of fibrosis). On a cross-sectional basis, ALT performed better than ferritin in classifying fibrosis, with ALT having an AUC of 0.80 (95% CI 0.66–0.94) and ferritin having an AUC of 0.63 (95% CI 0.38–0.87). LIC performed poorly at discriminating fibrosis from no fibrosis (AUC 0.30; 95%CI 0.0–0.82). The highest positive likelihood ratios for fibrosis were for a ferritin cutoff of 5000 ng/mL (LR+ 5.7) and an ALT cutoff of 65 U/L (LR+ 5.2). Longitudinal analysis did not reveal any statistically significant relationship between changes in fibrosis status and changes in ferritin, ALT, LIC, TIS, and cumulative red cell transfusion volume.

Among chronically transfused people with SCD, liver fibrosis most often does not persist or progress, as detected by serial core liver biopsies. On a cross-sectional basis, serum ALT >65 U/L and serum ferritin >5000 ng/mL are cutoffs associated with the highest likelihood of liver fibrosis. Cross-sectional or longitudinal measurements of LIC are not associated with fibrosis.

The progression of liver fibrosis is minimal among people with SCD who receive chronic red cell transfusions for up to 17 years. Serum biomarkers may be used to inform when investigations for fibrosis are warranted.

No relevant conflicts of interest to declare.