Leukocytosis is a risk factor for lung function deterioration in children with sickle cell disease

The decline in lung volumes associated with sickle cell disease (SCD) may begin in childhood. Risk factors for early restrictive lung disease may include SCD severity markers such as leukocytosis.

We examined the relationship between early alteration of lung function and extra-pulmonary markers of SCD severity.

We analyzed pulmonary function test results for 184 SCD children (mean age 12.6 y) enrolled in a pediatric cohort.

Total lung capacity (TLC) and vital capacity (VC) were not associated with a history of acute chest syndrome. Lower TLC values were significantly associated with three independent factors: older age, previous acute episodes of anemia <6 g/dl, and higher baseline white blood cell counts. Only the baseline WBC count and age were independent risk factors for lower VC. Relative risks to have a TLC or a VC lower than the mediane value in our population were significantly associated to the baseline leukocytosis (per 10(9) G/L), after adjustment on age, sex, genotype, baseline Hb, and treatment (RR (95% CI) =1.16 (1.04-1.29) p<0.009, and 1.17 (1.06-1.29) p<0.002, respectively). The obstructive pattern, defined by FEV1/FVC ratio, was not significantly associated to biological parameters.

Hemolysis and leukocytosis were independent risk factors for an early decline in lung volumes in this pediatric SCD cohort.