Mortality, Asthma, Smoking and Acute Chest Syndrome in Young Adults with Sickle Cell Disease

Abstract

Sickle cell disease (SCD) patients with asthma have an increased risk of death. Acute chest syndrome (ACS) is a major cause of mortality in patients with SCD, and ACS may be more common in SCD patients who smoke. The purpose of this study was to test the hypothesis that mortality in young adults with SCD would be greater than that of controls during a 10-year period and to determine whether asthma, reduced lung function, ACS episodes, and/or smoking predicted mortality during the follow-up period. The outcomes during a 10-year period were ascertained of SCD patients and race-matched controls who had taken part in a pulmonary function study when they were between age 19 and 27 years. Smoking and asthma status and whether they had had ACS episodes were determined, and lung function was measured at the initial assessment. Seventy-five subjects with SCD were followed for 683 patient years. There were 11 deaths with a mortality rate of 1.6 deaths per 100 patient years, which was higher than that of the controls; one death in 47 controls was observed for 469 patient years with a mortality rate of 0.2 per 100 patient years (p = 0.03). There were no significant associations of body mass index, recurrent episodes of acute chest, steady state haemoglobin, or gender with mortality. Adjusting for baseline lung function in SCD patients, "current" asthma [hazard ratio (HR) 11.2; 95 % confidence interval (CI) 2.5-50.6; p = 0.002] and smoking [HR 2.7; (95 % CI 1.3-5.5); p = 0.006] were significantly associated with mortality during the 10-year period. Our results indicate that young adults with SCD should be discouraged from smoking and their asthma aggressively treated.