P1422: prevalence and risk factors for retinopathy in sickle cell disease

Topic: 26. Sickle cell disease Background: The UK “natural history study” is a real-world multi-site study of adults with sickle cell disease (SCD) in the UK collecting all standard-of-care clinical data. After12 months, 241 individuals have been recruited: mean age 40.5 (std dev 13.9, range 8-79) with 149 (61.8%) female, and with sickle genotype: 156 HbSS (64.7%), 73 (30.3%) HbSC, 11 (4.6%) HbSB+ thal and 1 (0.4%) HbSHPFH. Retinopathy is one of the commonest sites of end organ damage in SCD but little is known about factors increasing the risk of developing retinopathy. All patients are offered annual retinal screening in specialist eye clinics: 183/241 have been screened. Aims: To investigate the prevalence and risk factors for development of sickle retinopathy. Methods: Clinical history, treatment history, admission rate, laboratory variables, steady state observations were assessed in univariate logistic analysis (with age and sex as cofactors), and significant results compared in a multivariate logistic analysis. Prior to assessment, non-normal data were transformed to a normal distribution for analysis. Results: 111 of 183 individuals assessed (60.7%) had evidence of retinopathy. Univariate analysis results are in the table. Risk of retinopathy is increased in: HbSC (49/61) compared to HbSS (61/115) (p<0.001), males (51/68) compared to females (59/108). Rising age was associated with increased risk of retinopathy. When analysing by age groups, there were similar prevalence rates in the 30-50 and >50 age groups. Increased risk of retinopathy was also associated with lower HbF% and lower transferrin saturations. Notably, there was no association with BMI, oxygen saturations, full blood counts, renal function markers, haemolytic markers, diabetes mellitus, hypertension, markers of disease severity. Multivariate analysis: Only HbF%, age, sex remained significant in multivariate analysis, see table. Summary/Conclusion: Male sex, rising age and low HbF% genotype are all associated with increased risk of sickle retinopathy in a multivariate analysis. Age analysis but subgroups suggested that, if individuals acquire retinopathy, then this is typically done by age 30-50 years rather than having an ongoing risk in later years. Low HbF% is much more commonly seen in HbSC than HbSS genotypes and raises the question that, in HbSC, it is the absence of HbF%, not a higher total Hb or the presence of HbC%, which gives rise to increased risk of retinopathy. HbF% results are steady-state results including both patients with high native HbF% and those with higher HbF% induced by hydroxycarbamide. It also provides some observational evidence that hydroxycarbamide could be considered to prevent/treat sickle retinal change. These data remind clinicians to promote retinal screening to otherwise seemingly “mild” patients with SCD.Keywords: Sickle cell disease, Sickle