Cost-Effectiveness of Vitamin D Supplementation in Pregnant Woman and Young Children in Preventing Rickets: A Modeling Study

Abstract

Background: Literature on the cost of management of rickets and cost-effectiveness of vitamin D supplementation in preventing rickets is lacking. Methods: This study considered the cost-effectiveness of providing free vitamin D supplementation to pregnant women and children <4 years of age with varying degrees of skin pigmentation to prevent rickets in children. Estimates for the prevalence of rickets were calculated using all cases of rickets diagnosed in Central Manchester, UK and census data from the region. Cost of management of rickets were calculated using National Health Service, UK tariffs. The efficacy of vitamin D supplementation was based on a similar programme implemented in Birmingham. Quality of life was assessed using utility estimates derived from a systematic literature review. In this analysis the intervention was considered cost-effective if the incremental cost-effectiveness ratio (ICER) is below the National Institute for Health and Care Excellence, UK cost-effectiveness threshold of £20,000 per Quality-adjusted life year (QALY). Results: Fifty-seven patients (26 dark, 29 medium and 2 light skin tones) were managed for rickets and associated complications over 4-years. Rickets has an estimated annual incidence of 29·75 per 100,000 children <4 years of age. In the dark skin tone population vitamin D supplementation proved to be cost saving. In a medium skin tone population and light skin tone populations the ICER was £19,295 per QALY and £404,047 per QALY, respectively. Conclusion: Our study demonstrates that a vitamin D supplementation to prevent rickets is cost effective in dark and medium skin tone populations.

Keywords: cost-effectiveness; decision tree model; incremental cost-effectiveness ratio; prevention; quality adjusted life years; rickets.

Figure 1

The structure of the decision tree analytic model. The model consists of two arms—current and alternative practices. Stage 1 represents the first 4 years of life, if a child developed rickets they could recover completely or recover but experience lifelong complications, children could also die as a result of all-cause mortality. In Year 5 all alive children transition to stage 2, where they can be vitamin D deficient and in their latter life experience disutility and increased mortality risk, or not. Children would remain in the stage 2 for the remainder of their lifetime as the deficiency prevalence in the cohort is assumed to be constant.

Figure 2

Cost-effectiveness acceptability plane for the homogenous population subgroups (base-case analysis). Cost effectiveness acceptability plane was generated in the probabilistic sensitivity analysis and illustrates differences in costs and treatment outcomes between current and alternative practices, taking parameter uncertainty into account. Each dot represents a random probabilistic estimate of the incremental costs and quality adjusted life years (QALYs). Cost-effectiveness probabilities presented in the base case analysis are calculated as a proportion of these samples below the threshold values. The mean price per QALY value for the subgroup consisting of children with dark skin tone is below the “x” axis meaning the intervention is cheaper than the current practice; the price per QALY estimates for the subgroup consisting of children with medium skin tone are scattered in the upper quadrant around the threshold lines, illustrating uncertainty of intervention's cost-effectiveness. The price per QALY estimates for the subgroup consisting of children with light skin tones are concentrated along the “y” axis, well above budget threshold lines, illustrating minimal health gains and considerably higher costs.

Figure 3

(A–E) Univariate sensitivity analysis, effect of the parameter variation between 2·5th and 97·5th quintile on the incremental cost-effectiveness ratio (ICER) value.