Chronic Kidney Disease and Mild Elevations in Pulmonary Arterial Systolic Pressure Are Associated with Increased Mortality in Adult Patients with Sickle Cell Disease.

Pulmonary arterial hypertension (PAH) has recently been shown to be an important predictor of prognosis in sickle cell disease (SCD). We studied this association in a large population of adults with SCD.

215 patients with sickle cell syndromes in whom echoes had been performed, 113 as outpatients and 102 as inpatients, were identified from our database. Clinical characteristics were analyzed, and survival data were extracted from a national mortality registry. At the time of examination, subjects were 39 ± 14 years old, with hematocrits (Hcts) of 23.6 ± 4.4. 78 out of 213 patients who had undergone echoes had PAH (PASP ≥ 40 mmHg) on echocardiogram. Those patients were older (41 ± 15 vs 37 ± 13 years, p=0.03), had higher creatinine values (1.3 vs 0.9 mg/dL, p=0.01) higher serum alkaline phosphatase levels (172.2 ± 23.2 vs 104.5 ± 5.5 U/L, p=.0058), and were more often taking anti-hypertensive medications (38 vs 17%, p<0.001). During a median follow-up of 7.8 years [interquartile range (IR); 3.9, 10.0] there were 30 deaths. In a multivariate Cox proportional hazards model, PAH (hazard ratio (HR) 11.3; 95% CI 2.7, 47.9), chronic kidney disease (CKD) (HR 17.0; 95% CI 3.7, 79.1, defined as an estimated glomerular filtration rate, eGFR, of <60 cc/min/1.73 m²) and hyperbilirubinemia (HR 13.1; 95% CI 2.0, 83.9) independently predicted mortality after adjustment for inpatient/outpatient status, age, sex, blood counts, measurement of chamber size and ventricular function on echocardiogram, oxygen saturation, history of transfusion and background medical therapy. The association of PAH and mortality was not modified by inpatient/outpatient status (p=0.6).

In a community-based academic center, we found that mild elevation in PASP on echocardiogram, whenever obtained (see figure), depressions in eGFR (see figure), and hyperbilirubinemia were highly predictive for mortality in sickle cell disease. It is unclear whether these relationships are causal or an epiphenomenon of severe underlying disease. Hemolysis (lower Hcts, higher Lactate dehydrogenase levels), implicated in other studies, was not prominent in the PAH cohort.

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No relevant conflicts of interest to declare.