The Effect Of Microalbuminuria On Duration Of Hospitalization In Adult Sickle Cell Disease Patients With Pain Crisis

Sickle cell disease (SCD) is a genetic blood disorder of hemoglobin resulting in severe morbidity and early mortality. The prevalence of microalbuminuria and/or proteinuria in children with SCD varies from 18 to 28% and increases with age. However, the exact prevalence in adults in not known. In the general population, the presence of albuminuria has been shown to be associated with all cause mortality. The urine microalbumin to creatinine ratio (MA) is considered to be an early sign of impending sickle cell nephropathy. We sought to investigate the association of MA with various SCD genotypes (HbSS, HbSC, HbS/β-thalassemia) in our clinic and also the length of stay (LOS) in hospitalized SCD patients with acute pain crisis.

Twenty-eight consecutive SCD patients diagnosed in our clinic by hemoglobin electrophoresis were included in our study. The patients (pts) age, gender, hemoglobin electrophoresis, and baseline MA were obtained. Based on their MA level they were divided into two groups, abnormal MA (MA ≥ 30 mg/g creatinine) or normal MA (< 30 mg/g creatinine). Eleven of these 28 patients were eventually hospitalized for a sickle cell related pain crisis. Their MA level was obtained within 24-hours of hospital admission and their hospitalization length of stay (LOS) was also recorded. We analyzed the association between the two groups of patients, those with normal or abnormal MA, with the different genetic variants of SCD in both our clinic and hospitalized pts. Furthermore, for hospitalized pts we also assessed an association of MA with their mean LOS. The Chi-square test/Fisher’s exact test was used for categorical variables and the T-test/Mann-Whitney test was used for numerical variables.

All twenty-eight patients were African American without significant renal impairment, with 11, 10, and 7 pts with SS, SC and S β-thalassemia (Sβ), respectively. Fifteen of these pts had abnormal MA, 12 pts were female. The median age was 35.5 yrs (range, 19 - 59), median LOS was 3.5 days (range, 2-8). The SS pts had higher abnormal MA levels followed by SC and then Sβ (p=0.03) (Table 1). There was no significant difference in gender between the two groups (p=0.2). SCD pts admitted to the hospital for pain crisis with an abnormal MA within 24-hours of admission had a significantly higher mean LOS when compared to pts with normal MA (p=0.0089) (Table 1).

Microalbuminuria is more prevalent in the severe genotypes of SCD disease such as SS and SC vs. Sβ pts. Thereby, MA might be a useful biomarker of generalized SCD vasculopathy, in addition to a known marker of progressive nephropathy. Furthermore, MA has a significant impact on length of hospitalization. An abnormal MA obtained within the first 24-hrs of hospitalization of a SCD pt in pain crisis was predictive of prolonged hospital duration. Early and more aggressive supportive care symptom management for those patients might be a reasonable option but requires more study. Further large prospective clinical trials are needed to validate our findings.

No relevant conflicts of interest to declare.