Cardiorenal risk prevalence in sickle cell hemoglobinopathy

The spectrum of kidney functional and structural alterations in sickle cell hemoglobinopathy (SCH) is broad. Also, morbidity and mortality from end organ dysfunction, especially cardiorenal dysfunction, are substantial. Consequently, screening an SCH population prospectively for surrogate markers of cardiorenal risk such as albuminuria and intima-media thickness (IMT) was the aim of this cross-sectional study.

We screened 165 patients with SCH over 4 months at the Primary Care Department, King Abdulaziz Armed Forces Hospital, Saudi Arabia. The 133 who fulfilled the inclusion criteria have been referred for further investigations. Anthropometric evaluation of body mass index (BMI) and blood pressure (BP), determination of 24-hour urine albuminuria, fasting lipids, computed atherogenic risk ratio (ARR), estimated glomerular filtration rate (eGFR), common carotid artery (CCA) IMT measurements, and hemoglobin (Hb) electrophoresis were done.

Increased urinary albumin excretion (UAE) rate [380 (272.2-489.6) mg/day; mean and 95% confidence interval (95% CI) of mean] was detected in 24% of SCH patients (6 males and 26 females). Microalbuminuria (168.8 +/- 59.7 mg/day) was noted in the majority (63.6%) while macroalbuminuria (752.7 +/- 205.4 mg/day) was detected in a smaller percentage (36.4%). Patients with sickle cell disease (SCD) contributed about 66.6% of subjects with microalbuminuria and 100% of those with macroalbuminuria, while most individuals with sickle cell trait (89%) were normoalbuminuric (p < 0.0001). Preclinical atherosclerosis (increased CCA IMT and/or atheromatous plaques) was noticed in 68.8% of SCH individuals with increased UAE (ANOVA p = 0.003). The microalbuminuric and macroalbuminuric patients had comparable BMI, BP values and lipid profiles. However, the microalbuminuric sicklers were significantly younger (28.4 +/- 6.7 vs. 34.0 +/- 7.2 years, p = 0.04), less anemic (Hb: 9.13 +/- 2 vs. 7.47 +/- 0.8 g/dl, p = 0.015), with lesser atherosclerosis (IMT; 0.68 +/- 0.1 vs. 0.78 +/- 0.1 mm, p = 0.004) and higher eGFR (83.3 +/- 17.2 vs. 61 +/- 10.7 ml/min/1.73 m(2), p = 0.0004) compared to those with macroalbuminuria. UAE correlated positively with age (r = 0.591, p = 0.0001), systolic BP (r = 0.483, p = 0.005), IMT (r = 0.399, p = 0.024) and negatively with Hb (r = -0.409, p = 0.02), and eGFR (r = -0.620, p = 0.0001). By univariate analysis, the significant indicators of UAE in SCH patients were age (p = 0.05), BMI (p = 0.041), IMT (p = 0.018) and eGFR (p = 0.016). Also, increased risk (odds ratio) of albuminuria was noted with SCD, age, anemia, abnormal eGFR, obesity, and ARR.

Markers of cardiorenal risk such as albuminuria and IMT are common findings in SCH patients of Arabic descent and could be useful screening tools to identify sicklers at risk for cardiovascular and renal events.