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Physiologic mechanisms can predict hematologic responses to iron supplements in growing children: a computer simulation model^1,2,3

¹ From the Departments of Nutritional Sciences (SZ), Public Health Sciences (BF, SZ, and GT), and Health Policy, Management and Evaluation (WS, BF, and GT), University of Toronto, Toronto, Canada; the Department of Pediatrics (SZ and BF), the Division of Rheumatology (BF), and the Research Institute (MT, SZ, and BF), The Hospital for Sick Children, University of Toronto, Toronto, Canada; the Department of Medicine, The University Health Network, University of Toronto, Toronto, Canada (GT); The Centre for International Health, University of Toronto, Toronto, Canada (WS and SZ); and the Medical Advisory Secretariat, Ministry of Health and Long-Term Care, Government of Ontario, Toronto, Canada (WS)

Background: Iron deficiency is the most common preventable nutrition problem in developing countries. Several randomized clinical trials (RCTs) have been conducted to determine the effectiveness of various iron dosing schemes in multiple settings.

Objective: The objective was to determine whether enough is known about iron metabolism to predict hemoglobin and serum ferritin (SF) concentrations with a computer model and whether the model could be used as a substitute for new RCTs.

Design: Guided by the physiology of iron absorption and regulation, we used data from RCTs that tested iron Sprinkles to develop a computer model. Of 2 RCTs in Ghana, we used 1 to compute the amount of iron absorbed from a given dose in anemic and nonanemic children and the other to compute the resulting change in hemoglobin concentrations. We used this model to predict hemoglobin and SF concentrations in a new RCT in China and compared model-predicted values with actual values by using summary statistics (means and medians) and quantile-quantile plots.

Results: The model-predicted hemoglobin means were within ±2 g/L, and SF medians were within ±3 µg/L of the corresponding means and medians of the actual values. On quantile-quantile plots, the predicted hemoglobin quantiles were within ±5 g/L, and SF quantiles were within ±10 µg/L of the corresponding quantiles of the actual values.

Conclusion: Our model of iron metabolism can accurately predict hemoglobin and SF concentrations after iron supplementation with Sprinkles in children; the model can thus obviate the need for repeating RCTs in multiple settings.

Key Words: Markov model • Monte Carlo simulation • clinical trial • iron deficiency