Severity of Sickle Cell Disease in Yemeni Children

Homozygous sickle cell disease (SCD) is characterized by a highly variable clinical course, and marked individual variation in disease severity [1]. Quantitative severity assessment could provide a useful tool for patient selection for therapeutic and preventive interventions [2]. In children, severity assessment is more difficult than adults due to age-related clinical, haematological and immunological changes [3]. We assessed quantitatively SCD severity in Yemeni children. The study was conducted at Al-Wahda Hospital, Aden. Children (<16 years) with confirmed Hb SS by electrophoresis were included, as previously described [4]. A Severity Index (SI) was calculated based on frequency of painful crises, hospitalization, blood transfusion, infection and specific complications, during the previous year. Children were grouped into mild (≤6) and severe (>6) score categories [5]. One hundred and two children (56 males) were enrolled, (mean age 7.2 years). Sixty-five children (63.7%) categorized as severe and 37 (36.3%) as mild. Severe symptoms were more frequent in females, and increased with age from 5 years (p < 0.01) (Fig. 1). Females had a higher rate of painful crisis (crises/child/year) than males (3.16 vs 2.0, p < 0.05). Painful crisis, hospital admission and blood transfusions were more frequent in the severe category (all p < 0.001) (Table 1). Stroke (4.9%) and gallbladder stone (4.9%) occurred only in children with severe disease. Malaria was diagnosed in 21 children (16 in the severe and 5 in the mild group). Percentage of Hb F was lower in severe cases (p < 0.01). Polymorphonuclear leucocytes, total and direct bilirubin were higher in severe cases (all p < 0.05). There were no significant differences for Hb, serum total protein, albumin, liver transaminases, BUN and creatinine. Child age category by gender and severity index of homozygous SCD. Clinical events, complications and relevant haematological and biochemical parameters by SI category Values are given as n (%), mean ± SD, median (Interquartile range, IQR). *p < 0.05, **p < 0.01, ***p < 0.001 (t-test, or Mann–Whitney U test). Clinical events, complications and relevant haematological and biochemical parameters by SI category Values are given as n (%), mean ± SD, median (Interquartile range, IQR). *p < 0.05, **p < 0.01, ***p < 0.001 (t-test, or Mann–Whitney U test). This is the first reports of two forms of SCD in Yemen. Clinical variation in Saudi patients has been related to different levels of Hb F and the presence of African and Arab-Indian βs haplotypes [6]. In Yemen βs haplotype is unknown, although the diverse clinical manifestations suggest mixed polymorphisms. We used the SI proposed by El-Hazmi [5], which had been validated in previous studies from Saudi Arabia [5,7–9] and Africa [10]. The average SI in Yemeni children was 7.8, with 63.7% scored as severe, which compares to 73.8% in Saudi Arabia [7], and 51.7% in Senegal [10]. A severe SI was more frequent in females. Previous studies have reported higher incidence of painful crisis in females during the first decade of life [8], and in males after 15 years [9]. The reasons for these age and sex differences remain unclear. The low mean Hb F% (4.0 ± 3.9) was comparable to reports from Riyadh (3.6 ± 2.9) and Qunfuda (5.0 ± 3.9) in Saudi Arabia [10]. Even with low Hb F% small increments may ameliorate painful crises, a core component of the severity scoring system [9]. There was a higher frequency of malaria in severe SCD. These children will more frequently be symptomatic, and have different haematological and immunological responses. This report on SCD severity from the Yemen highlights disease variability in this region. The use of SI could facilitate comparison between geographically diverse study groups.