Prevalence and factors associated with asthma among children with sickle cell disease aged 6-17 years attending the Sickle Cell Clinic at Mulago national Referral Hospital

Abstract

Sub-Saharan Africa harbours more than three quarters of the world Sickle cell disease (SCD) burden, coinciding with a rapidly growing asthma prevalence in the region. Murine studies have demonstrated the classical inflammatory markers of asthma in mice with SCD. The Cooperative study of SCD revealed a 17% occurrence of asthma among children with SCD. Literature on this comorbidity is limited especially in Africa, with precarious diagnostic and treatment approaches to asthma among this special population. Objective: To determine the prevalence and factors associated with asthma among children with SCD aged 6-17 years attending the sickle cell clinic at Mulago national referral hospital also called the Mulago Hospital Sickle cell clinic (MHSCC). Methods: A cross-sectional study was conducted at the MHSCC between November 2024 and February 2025. A total of 305 children were systematically sampled on each of the clinic days and successfully enrolled into the study. Data on key variables was collected using a pre-tested ISAACguided questionnaire that included a review of participants’ clinic records, physical examination, and laboratory workup. Spirometry was performed in participants with characteristic asthma symptoms to confirm asthma diagnosis. STATA v18.0 was used for analysis, participant characteristics were described, and the prevalence of asthma was then established as a proportion of children with SCD found to have the characteristic asthma symptoms with a post-bronchodilator increase in FEV1 of  10% predicted on spirometry. Logistic regression was carried out to establish factors associated with the SCD-asthma comorbidity. Results: The prevalence of asthma among children with SCD in this study was 4.3% (13/305) with a female preponderance (7/13). The mean age of children enrolled was 10.7 years (SD 3.3), with a nearly equal male (51.1%) to female participation. Hospitalization in the past year was reported in 111 (36.4%) children. Having been a preterm at birth was associated with a 30-fold increase in the risk for asthma aOR 30.74 (95% CI; 3.31 – 285.69, p=0.003). The SCD-Asthma comorbidity was associated with a 6 times higher likelihood of having been hospitalized in the past year aOR 5.78 (95% CI; 1.71 – 19.52, p= 0.005). Conclusion: This study highlights the occurrence of asthma in SCD in our clinical setting and the need for meticulous assessments to avoid any missed opportunities for asthma diagnosis