Comparison between Adult Patients with Sickle Cell Disease of Sub-Saharan African Origin Born in Metropolitan France and in Sub-Saharan Africa

Abstract

Sickle cell disease (SCD) prevalence has increased rapidly in Europe as a result of an increase in the life expectancy of these patients and the arrival of SCD migrants from Africa. The aim of our study was to compare the phenotypes of adult patients born in Sub-Saharan Africa (SSA) who migrated to France with those of patients with the same origin who were born in France. This single-center observational study compared the demographic, clinical and biological characteristics of SCD adult patients of SSA origin who were born in France or SSA. Data were collected from computerized medical charts. Groups were compared using multivariate logistic regression with adjustment for age, gender and type of SCD. Of the 323 SCD patients followed in our center, 235 were enrolled, including 111 patients born in France and 124 patients born in SSA. SCD genotypes were balanced between groups. Patients born in Africa were older (median age 32.1 (24.4–39) vs. 25.6 (22.1–30.5) years, p < 0.001) and more often women (n = 75 (60.5%) vs. 48 (43.2%), p = 0.008). The median age at arrival in France was 18 years (13–23). The median height was lower among patients born in SSA (169 (163–175) vs. 174.5 cm (168–179), p < 0.001). Over their lifetimes, patients born in France had more acute chest syndromes (median number 2 (1–4) vs. 1 (0–3), p = 0.002), with the first episode occurring earlier (19 (11.6–22.3) vs. 24 (18.4–29.5) years, p < 0.007), and were admitted to intensive care units more often (53.3% vs. 34.9%, p = 0.006). This difference was more pronounced in the SS/Sβ0 population. Conversely, patients born in SSA had more skin ulcers (19.4% vs. 6.3%, p = 0.03). No significant differences were found in social and occupational insertion or other complications between the two groups. Patients born in SSA had a less severe disease phenotype regardless of their age than those born in France. This difference could be related to a survival bias occurring in Africa during childhood and migration to Europe that selected the least severe phenotypes.

Epidemiology and disease burden of sickle cell disease in France: A descriptive study based on a French nationwide claim database

“…Additionally, it is likely that some patients with SC and Sβ + (SCD genotypes), which can present with less severe symptoms, and so lower rates of inpatient stays, have been excluded from group 2 by the >1 inpatient stay cut-off. The SC and Sβ + genotypes could represent up to 20–30% of SCD patients in France [ 12 , 13 , 21 , 22 ]. Therefore, while group 1 probably includes sickle cell traits, it is likely that group 2 excludes some SC and Sβ + patients, leaving the SCD prevalence and results somewhere in the middle between groups 1 and 2.…”

“…This might also explain why the median age observed is slightly higher than previous published studies [ 25 , 26 ]. Similarly, given the high prevalence of SCD in immigration from sub-Saharan Africa [ 12 , 13 , 27 ], and with sub-Saharan Africa representing 43% of the beneficiaries of AME [ 28 ]. a specific health insurance scheme for immigrants not covered by NHI, prevalence is further underestimated by this exclusion.…”

“…Group 2 (G2) was more strictly defined as patients with at least two inpatient stays having an associated ICD diagnosis code of D57x (excluding D573 for sickle cell traits) between 2006 and 2016, or ALD status with an associated ICD diagnosis code of D57 until 2016 or at least one hydroxyurea reimbursement between 2006 and 2016. It was assumed that this second group would include fewer misclassified patients as it required at least two inpatient stays associated with sickle cell disease, assuming that SCT patients are rarely rehospitalized compared to SCD [ 13 , 18 ].…”

“…However, it is not possible to determine the prevalence of SCD patients in France by extrapolating newborn screening data. Indeed, a significant proportion of patients are of immigrant origin [11][12][13]. The recent increase in survival [14][15][16] due to earlier and better management also makes it difficult to extrapolate the prevalence from birth incidence as increased survival leads to more prevalence.…”

Bibliometric analysis of global sickle cell disease research from 1997 to 2017

“…However, it is noteworthy that Brazil (South America), France (Europe) and Nigeria (Africa) retain the highest sickle cell disease burden in their continents. 17 , 32 , 33 This could partly explain the seeming research interest of the duo of Brazil and Nigeria in sickle cell disease research (in relation to other medical research) amidst their limited resources, as compared to other economically advanced countries on the list, such as France. Moreover, the low comparative participation index of Germany in SCD research, in relation to general research in medicine, was also remarkable.…”