Age and altitude of residence determine anemia prevalence in Peruvian 6 to 35 months old children

Abstract

Background: A Demographic and Family Health Survey (ENDES, for Encuesta Demográfica y de Salud Familiar in Spanish) is carried out annually in Peru. Based on it, the anemia prevalence was 43.6% in 2016 and 43.8% in 2017 using the WHO cutoff value of 11 g/dL and the altitude-correction equation.

Objective: To assess factors contributing to anemia and to determine its prevalence in Peruvian children 6 to 35 months old.

Methods: We used the MEASURE DHS-based ENDES survey to obtain representative data for11364 children from 6 to 35 months old on hemoglobin and health determinants. To evaluate normal hemoglobin levels, we used the original WHO criterion of the 5th percentile in children without chronic malnutrition and then applied it to the overall population. Relationships between hemoglobin and altitude levels, usage of cleaning methods to sanitize water safe to drink, usage of solid fuels and poverty status were tested using methodology for complex survey data. Percentile curves were made for altitude intervals by plotting hemoglobin compared to age. The new anemia rates are presented in graphs by Peruvian political regions according to the degree of public health significance.

Results: Hemoglobin increased as age and altitude of residence increased. Using the 5th percentile, anemia prevalence was 7.3% in 2016 and 2017. Children from low altitudes had higher anemia prevalence (8.5%) than those from high altitudes (1.2%, p<0.0001). In the rainforest area of Peru, anemia prevalence was highest (13.5%), while in the highlands it was lowest (3.3%, p<0.0001). With access to safe drinking water and without chronic malnutrition, anemia rates could be reduced in the rainforest by 45% and 33%, respectively.

Conclusion: Anemia prevalence in Peruvian children from 6 to 35 months old was 7.3% in 2016 and 2017.

Fig 1. Hemoglobin trends according to observed and WHO altitude-corrected values.

Red line parallel to X axis represents the 11 g/dL anemia threshold and the red line parallel to Y axis the 11000 feet boundary of WHO/CDC altitude-correction factor equation.

Fig 2. Hemoglobin percentiles by age and altitude categories (masl).

In order, from bottom to top: p5 (blue), p50 (red), p95 (green). Percentile curves as estimated using altitude of residence show that Hb increases along with age. However, some differences arise: At lower altitudes, the p5 curve follows the equation 8.47+ 2.87*10⁻²*x+ 6.04*10⁻⁴*x² and p50 follows the equation 10.16+ 6.12*10^−2*x- 5.02*10⁻⁴*x². At moderate altitudes the p5 curve follows the equation 9.94–5.17*10⁻²*x+ 2.45*10⁻³*x² with the lowest estimated value found at 10.6 months, and the p50 curve follows the equation 11.20+ 5.81*10⁻²*x- 2.72*10⁻⁵*x² which shows an upward trend across the age range. At high altitudes the p5 curve follows the equation 10.55–4.08*10⁻²*x+ 2.38*10⁻³*x² with the lowest estimated value found at 8.6 months. The p50 equation is 12.20+ 2.42*10⁻²*x+ 4.11*10⁻⁴*x², which follows an upward curve for the age range. At very high altitudes p5 follows 11.49–10.09*10⁻²*x+ 4*10⁻³*x² with the lowest estimated value found at 12.5 months. The p50 follows 13.15+ 1.31*10⁻³*x+ 9.78*10⁻⁴*x² which has an upward trend for the given age range.

Fig 3. Anemia rates by political regions.

(A) Anemia using WHO guidelines. The numbers correspond to political regions as presented in Table 4. (B) Anemia using Hb <11g/dl as cutoff point. (C) Recalculated anemia using p5.