Vitamin D, calcium or a combination of vitamin D and calcium for the treatment of nutritional rickets in children.

BACKGROUND Nutritional rickets is a disease which affects children, especially in low- and middle-income countries. It causes problems such as skeletal deformities and impaired growth. The most common cause of nutritional rickets is vitamin D deficiency. Vitamin D administered with or without calcium is commonly regarded as the mainstay of treatment. In some sunny countries, however, where children are believed to have adequate vitamin D production from exposure to ultraviolet light, but who are deficient in calcium due to low dietary intake, calcium alone has also been used in the treatment of nutritional rickets. Therefore, it is important to compare the effects of vitamin D, calcium or a combination of vitamin D and calcium for the treatment of nutritional rickets in children living in different settings. OBJECTIVES To assess the effects of vitamin D, calcium or a combination of vitamin D and calcium for the treatment of nutritional rickets in children. SEARCH METHODS We searched CENTRAL, MEDLINE, LILACS, WHO ICTRP Search Portal and ClinicalTrials.gov. The date of the last search of all databases was 25 July 2019. We applied no language restrictions. SELECTION CRITERIA We included randomised controlled trials (RCT) involving children aged 0 to 18 years with nutritional rickets which compared treatment with vitamin D, calcium or a combination of vitamin D and calcium. DATA COLLECTION AND ANALYSIS Two review authors independently screened the title and abstracts of all studies, extracted data and assessed the risk of bias of included studies. We resolved any disagreements by consensus or recourse to a third review author. We conducted meta-analyses for the outcomes reported by study authors. For dichotomous outcomes, we calculated the risk ratio (RR) and 95% confidence interval (CI) and, for continuous outcomes, we calculated mean differences (MD) with 95% CIs. We assessed the certainty of the evidence of the included studies using GRADE. MAIN RESULTS We identified 4562 studies; of these, we included four RCTs with 286 participants. The studies compared two or more of the following: vitamin D, calcium or vitamin D plus calcium. The number of participants randomised to receive vitamin D was 64, calcium was 102 and vitamin D plus calcium was 120. Two studies were conducted in India and two were conducted in Nigeria. None of the included studies had a low risk of bias in all domains. Three studies had a high risk of bias in at least one domain. The age of the participants ranged between six months and 14 years. The duration of follow-up ranged between 12 weeks and 24 weeks. Two studies compared vitamin D to calcium. There is low-certainty evidence that, at 24 weeks' follow-up, calcium alone improved the healing of rickets compared to vitamin D alone (RR 3.26, 95% CI 1.59 to 6.69; P = 0.001; 1 study, 71 participants). Comparing vitamin D to calcium showed no firm evidence of an advantage or disadvantage in reducing morbidity (fractures) (RR 0.27, 95% CI 0.03 to 2.32; P = 0.23; 1 study, 71 participants; very low-certainty evidence). Adverse events were not reported. Two studies compared vitamin D plus calcium to vitamin D at 12 or 24 weeks. Vitamin D plus calcium improved healing of rickets compared to vitamin D alone at 24 weeks' follow-up (RR 3.06, 95% CI 1.49 to 6.29; P = 0.002; 1 study, 75 participants; low-certainty evidence). There is no conclusive evidence in favour of either intervention for reducing morbidity (fractures) (RR 0.24, 95% CI 0.03 to 2.08; P = 0.20; 1 study, 71 participants; very low-certainty evidence) or adverse events (RR 4.76, 95% CI 0.24 to 93.19; P = 0.30; 1 study, 39 participants; very low-certainty evidence). All four included studies compared vitamin D plus calcium to calcium at different follow-up times. There is no conclusive evidence on whether vitamin D plus calcium in comparison to calcium alone improved healing of rickets at 24 weeks' follow-up (RR 1.17, 95% CI 0.72 to 1.90; P = 0.53; 2 studies, 140 participants; very low-certainty evidence). Evidence is also inconclusive for morbidity (fractures) (RR 0.89, 95% CI 0.06 to 13.76; P = 0.94; 1 study, 72 participants; very low-certainty evidence) and adverse events (RR 4.29, 0.22 to 83.57; P = 0.34; 1 study, 37 participants; very low-certainty evidence). Most of the evidence in the review is low or very low certainty due to risk of bias, imprecision or both. None of the included studies assessed all-cause mortality, health-related quality of life or socioeconomic effects. One study assessed growth pattern but this was not measured at the time-point stipulated in the protocol of our review (one or more years after commencement of therapy). AUTHORS' CONCLUSIONS This review provides low-certainty evidence that vitamin D plus calcium or calcium alone improve healing in children with nutritional rickets compared to vitamin D alone. We are unable to make conclusions on the effects of the interventions on adverse events or morbidity (fractures).