Interventions for the prevention of nutritional rickets in term born children

Although only a few studies with different results exist, preventive measures against nutritional rickets appear reasonable in high risk groups until new data become available.

Rickets is a disease which affects the bone of growing children. Calcium and phosphate are important elements which form the bone. In nutritional rickets, initially the availability of calcium is diminished, later disturbances in phosphate occur. The shortage of calcium may be caused by limited intake or limited resorption in the gut. The latter is highly regulated by vitamin D, which can be synthesised from the skin after sun exposure or can be acquired from dietary sources, for example cod liver. Therefore, shortage of calcium, vitamin D or both may lead to nutritional rickets, which is mainly characterized by deformed bones, bone pain, convulsions or delayed development. Since the 1930s supplementation of vitamin D is used for the prevention of rickets in children, mainly in high-income countries; several other measures like supplementation of calcium or longer exposure of the skin to sunlight are also used. Over the time many factors have changed, for example nutrition, which provides calcium, air pollution, through which sun light is absorbed leading to a diminished synthesis of vitamin D in the skin, or social issues, for example child labour, again leading to limited sun exposure. Because of these changes we looked for studies conducted in the last 50 years which investigated patient-relevant outcomes. As patient-relevant outcomes we defined the occurrence of rickets, adverse effects of the intervention, mortality, health-related quality of life and costs.
Four trials enrolled approximately 1700 participants and lasted between nine months and two years. Study participants were aged from one month to 15 years. There were different results on the occurrence of nutritional rickets in different settings. Adverse effects were investigated in one study only.
Considering the partial high frequency of nutritional rickets, the obvious way of action of supplementation of vitamin D or calcium and the favourable risk-benefit ratio, preventive measures are reasonable in high risk groups like infants and toddlers. New studies investigating main and side effects of preventive measures against nutritional rickets in different age groups and in different countries are indicated.

Authors' conclusions: 

There a only few studies on the prevention of nutritional rickets in term born children. Until new data become available, it appears sound to offer preventive measures (vitamin D or calcium) to groups of high risk, like infants and toddlers; children living in Africa, Asia or the Middle East or migrated children from these regions into areas where rickets is not frequent. Due to a marked clinical heterogeneity and the scarcity of data, the main and adverse effects of preventive measures against nutritional rickets should be investigated in different countries, different age groups and in children of different ethnic origin.

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Background: 

Nutritional rickets is a disease of growing children leading to bone deformities, bone pain, convulsions or delayed motor development. Today, high-incidence of nutritional rickets is mainly found in low-income countries.

Objectives: 

To assess the effects of various interventions on the prevention of nutritional rickets in term born children.

Search strategy: 

Studies were obtained from computerised searches of The Cochrane Library, MEDLINE, EMBASE, LILACS and reference lists of relevant articles. We contacted authors of studies or reviews to obtain further studies.

Selection criteria: 

Studies were included if they were randomised controlled clinical trials, controlled clinical trials or prospective cohort studies comparing any intervention for the prevention of nutritional rickets in term born children with placebo or no intervention. Minimum duration of the intervention was three months for children under 12 months or six months for children over 12 months.

Data collection and analysis: 

Two authors independently extracted data and assessed study quality. Authors of studies were contacted to obtain missing information.

Main results: 

Four studies enrolled approximately 1700 participants. Trials lasted between nine months to two years. Three studies were randomised controlled trials, two of which showed a cluster randomised design; one trial probably was a controlled trial with researcher controlled group assignment. In children up to three years of age in Turkey, Vitamin D compared to no intervention showed a relative risk of 0.04 (95% confidence interval (CI) 0 to 0.71). Despite a marked non-compliance, a Chinese trial in children up to three years of age comparing a combined intervention of supplementation of vitamin D, calcium and nutritional counselling showed a relative risk of 0.76 (95% CI 0.61 to 0.95) compared to no intervention. In two studies conducted in older children in China and in France no rickets occurred in both the intervention and control group.

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