Prevalence of anemia and its association with asthma control in school-aged children: a cross-sectional study in Karachi, Pakistan (2025)

Asthma is a frequently encountered paediatric health problem, with various factors influencing disease control, including anemia. Anemia, regardless of the cause, is as an independent risk factor for lower respiratory tract infections but its association with asthma has not been thoroughly explored. Hence, we conducted this study to determine the frequency of anemia in asthmatic children and its effect, if any, on asthma control. We conducted a cross-sectional study in children of 6–15 years attending public or private schools in Karachi from February to March 2025. A non-probability convenience sampling technique was used to include the schools and asthmatic children. Asthmatic children were identified through physician-based diagnosis or self/parent-reported symptoms of asthma. Control of asthma was assessed using the GINA symptom control assessment. Anemia was identified using the HemoCue device with age appropriate haemoglobin cut-offs. Among 198 asthmatic children studied, anemia was present in 46.0% of participants. Male asthmatics were associated with lower odds of anemia (aOR = 0.41, 95% CI: 0.23–0.75, p = 0.003) and partly controlled asthma (aOR = 2.43, 95% CI: 1.25–4.70, p = 0.009) was significantly associated with higher odds of anemia. Children exposed to cigarette smoke were over twice as likely to be anemic (aOR = 2.05, 95% CI: 1.03–4.10, p = 0.042). No significant associations were found between anemia and clinical symptoms of asthma, school category, or maternal education level. We found a high prevalence of anemia in asthmatic children and the study highlights a notable association with anemic children who are more likely to have partly controlled asthma. These findings suggest that anemia may be an under-recognized factor associated with asthma control, prompting routine screening and management of anemia in asthmatic children.