Vitamin A status, other risk factors and acute respiratory infection morbidity in children

Abstract

Objective: This study evaluated the association between vitamin A status and the severity of acute respiratory infections (ARIs) in children, controlling for the influence of other known ARI risk factors.

Design: Case control study.

Setting: Ambulatory and hospital-based study.

Patients: Severe cases (N = 35) were children with ARI who were admitted to hospital for inpatient treatment, while mild cases (N = 32) were children with ARI who were treated as outpatients. The control group (N = 54) was selected from children with non-infectious diseases attending the outpatient department. Cases and controls were matched for age and area of residence.

Main outcome measures: Serum vitamin A levels and analysis of ARI risk factors.

Results: The mean (SD) vitamin A levels were 22.09 (7.27) micrograms/dl for the controls, 20.27 (11.11) micrograms/dl for the mild cases and 13.79 (7.60) micrograms/dl for the severe cases. All pairwise comparisons of levels of the three patient groups achieved statistical significance-severe and mild (P < 0.01), severe and control (P < 0.001) and mild and control (P = 0.03). After vitamin A levels were dichotomised, the odds ratios (and 95% confidence intervals) for severe versus mild cases were 2.1 (0.8-5.6), for mild versus controls 2.9 (0.8-10.5) and for severe versus controls 6.0 (2.0-19.4). A chi 2 for trend across the three groups was 13.2 (P = 0.001). Risk factors significantly associated with disease status included a history of hospital admission in the preceding 6 months, absence of a clinic card, poor housing and lack of electricity for indoor fuel use. Factors associated with poor vitamin A status included low weight for age, previous diarrhoeal disease and poor housing. Vitamin A status was independently associated with disease status in logistic regression modelling.

Conclusion: Vitamin A status has a strong association with severity of infection. The gradient of that association suggests a dose-response effect. The multifactorial nature of ARI severity and vitamin A status highlights the need for a comprehensive approach to public health programmes to address ARI. The role of vitamin A supplementation for at-risk groups is supported by this study, but needs to be clearly defined within a broader approach to health.