Dudley L, Hussey G, Huskissen J, Kessow G
Department of Community Health, University of Cape Town.
S Afr Med J. 1997 Jan;87(1):65-70.
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.
Case control study.
Ambulatory and hospital-based study.
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.
Serum vitamin A levels and analysis of ARI risk factors.
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.
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.
本研究评估了儿童维生素A状况与急性呼吸道感染（ARI）严重程度之间的关联，并控制了其他已知ARI危险因素的影响。
病例对照研究。
门诊和住院研究。
重症病例（N = 35）为因ARI住院接受治疗的儿童，轻症病例（N = 32）为接受门诊治疗的ARI儿童。对照组（N = 54）选自门诊就诊的非感染性疾病儿童。病例和对照按年龄和居住地区进行匹配。
血清维生素A水平及ARI危险因素分析。
对照组维生素A水平的均值（标准差）为22.09（7.27）微克/分升，轻症病例为20.27（11.11）微克/分升，重症病例为13.79（7.60）微克/分升。三组患者水平的所有两两比较均具有统计学意义——重症与轻症（P < 0.01）、重症与对照组（P < 0.001）、轻症与对照组（P = 0.03）。将维生素A水平二分法划分后，重症与轻症病例的比值比（及95%置信区间）为2.1（0.8 - 5.6），轻症与对照组为2.9（0.8 - 10.5），重症与对照组为6.0（2.0 - 19.4）。三组间趋势的卡方值为13.2（P = 0.001）。与疾病状态显著相关的危险因素包括前6个月有住院史、无门诊病历、住房条件差以及室内燃料使用无电。与维生素A状况不佳相关的因素包括年龄别体重低、既往腹泻病和住房条件差。在逻辑回归模型中，维生素A状况与疾病状态独立相关。
维生素A状况与感染严重程度密切相关。这种关联的梯度表明存在剂量反应效应。ARI严重程度和维生素A状况的多因素性质凸显了对公共卫生项目采取综合方法来应对ARI的必要性。本研究支持对高危人群补充维生素A的作用，但需要在更广泛的健康方法中明确界定。
