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BackgroundVaso-occlusive crisis (VOC), hallmark of sickle-cell disease (SCD), is the first cause of patients' Emergency-Room admissions and hospitalizations. Acute chest syndrome (ACS), a life-threatening complication, can occur during VOC, be fatal and prolong hospitalization. No predictive factor identifies VOC patients who will develop secondary ACS.MethodsThis prospective, monocenter, observational study on SS/S-β0thalassemia SCD adults aimed to identify parameters predicting ACS at Emergency-Department arrival. The primary endpoint was ACS onset within 15 days of admission. Secondary endpoints were hospitalization duration, morphine consumption, pain evaluation, blood transfusion(s) (BT(s)), requiring intensive care and mortality.FindingsAmong 250 VOCs included, 247 were analyzed. Forty-four (17.8%) ACSs occurred within 15 (median [IQR] 3 [2, 3]) days post-admission based on auscultation abnormalities; missing chest radiographs excluded three patients. Comparing ACS to VOC, respectively, median hospital stay was longer 9 [7–11] vs 4 [3–7] days (p < 0.0001), 7/41 (17%) vs 1/203 (0.5%) required intensive care (p < 0.0001), and 20/41 (48.7%) vs 6/203 (3%) required BTs (p < 0.0001). No patient died. The multivariate model retained reticulocyte and leukocyte counts, and spine and/or pelvis pain as being independently associated with ACS; the resulting ACS-predictive score's area under the ROC was 0.840 [95% CI 0.780–0.900], 98.8% negative-predictive value and 39.5% positive-predictive value for the real ACS incidence.InterpretationThe ACS-predictive score is simple, easily applied and could change VOC management and therapeutic perspectives. Assessed ACS risk could lead to earlier discharges or close monitoring and rapid medical intensification to prevent ACS.

Purpose Although strenuous exercise may expose sickle cell disease (SCD) patients to risks of vaso-occlusive crisis, evidence suggests that regular endurance exercise may be beneficial. This study aimed to test (i) the safety and usefulness of a submaximal incremental exercise in evaluating physical ability of SCD patients and identify a marker for the management of endurance exercise and (ii) the feasibility of endurance exercise sessions in SCD patients. Methods Twenty adults with SCD (12 men and 8 women) performed a submaximal incremental exercise used to determine the first lactate threshold (LT1) and stopped as soon as blood lactate concentration ([lactate]b) reached ≥4 mmol·L−1. Fifteen of those patients (8 men and 7 women) also performed three 30-min endurance exercise sessions at ~2.5 mmol·L−1 of [lactate]b on separate occasions. Results LT1 occurred at 47 ± 3 and 33 ± 3 W for men and women, respectively, demonstrating the extreme deconditioning and, thus, low physical ability of adult SCD patients. During endurance exercise, peripheral oxygen saturation and [lactate]b most often remained stable and within acceptable ranges. Conclusions The proposed strategy of submaximal incremental exercise allowed safe determination of LT1, an important parameter of patients’ physical ability. The study also demonstrated the feasibility and safety of individually tailored endurance exercises at ~2.5 mmol·L−1 of [lactate]b. These latter results suggest that endurance training programs may be considered for adult SCD patients and that the method proposed here may be helpful in that regard.

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