Hemoglobin Concentration in Children at Different Altitudes in Peru: Proposal for [Hb] Correction for Altitude to Diagnose Anemia and Polycythemia

Iron status and hemoglobin adjustment by altitude to define anemia in children aged 6 to 8 months living in Lima, Arequipa, Cusco and Puno

OBJECTIVE.

To describe the iron status profile and to propose hemoglobin adjustment factors for altitude for children aged 6 to 8 months in Lima, Arequipa, Cusco and Puno.

MATERIALS AND METHODS.

Cross-sectional study in children aged 6 to 8 months from four cities. We measured hemoglobin and other iron biomarkers, C-reactive protein (CRP), among others. To estimate the adjustment equation, we applied an exponential regression. We excluded children with iron deficiency (ID) and/or inflammation.

RESULTS.

The proportions of ID were higher in Puno and Arequipa, while inflammation did not exceed 19% in any of the cities. Hemoglobin showed an exponential increase at higher altitude. The adjustment equation was: 10.34249 x (1.00007 ^ Alt).

CONCLUSIONS.

Children residing in Arequipa and Puno showed higher rates of ID and lower iron reserves; furthermore, the increase in hemoglobin by altitude was exponential, showing the need to adjust hemoglobin at altitude.

Evaluation of dietary composition between hemoglobin categories, total body iron content and adherence to multi-micronutrients in preschooler residents of the highlands of Puno, Peru

BACKGROUND

The anemia prevalence is higher in highlands populations. It is assumed that iron deficiency anemia (IDA) in children is mainly due to low dietary intake. However, other suggest that high prevalence of anemia is due to an inappropriate hemoglobin (Hb) adjustment for altitude.

MATERIALS AND METHODS

Cross-sectional study conducted in 338 preschoolers (PSC) from Puno-Peru. Hb was measured in whole blood, and ferritin, Soluble transferrin receptor, and Interleukin 6 in serum.The dietary iron intake was assessed by 24-h dietary recall, using NutriCap Software. Hb concentration was assessed as adjusted or unadjusted for altitude.

RESULTS

With unadjusted Hb, the anemia prevalence was 4.7%, whereas after Hb correction, the prevalence raised-up to 65.6% (p < 0.001). Reciprocally, erythrocytosis proportion decreased from 20.35 to 0.30% (p < 0.001). Total Body Iron (TBI) showed that 7.44% had ID and 0.32% had IDA. PSC with normal unadjusted Hb levels have more protein and micronutrients intake than anemic ones. PSC with erythrocytosis consumed less fat, and more niacin and ascorbic acid than anemics. Total iron intake was lower in anemic than the other groups, but without statistical significance due to the standard deviation of the data in a small number of anemic PSC (n = 16). TBI, unadjusted Hb, and adjusted Hb were not different between groups consuming or not multimicronutrients.

CONCLUSIONS

The consumption of iron and iron status in children who live at high altitude is adequate, and that anemia could be due to other micronutrient deficiencies and/or that the adjustment of Hb by altitude is inappropriate.

Anemia and Associated Risk Factors in Pediatric Patients

Anemia is the most common hematologic abnormality identified in children and represents a major global health problem. A delay in diagnosis and treatment might place patients with anemia at risk for the development of rare but serious complications, including chronic and irreversible cognitive impairment. Identified risk factors contributing to the development of anemia in children include the presence of nutritional deficiencies, environmental factors, chronic comorbidities, and congenital disorders of hemoglobin or red blood cells. Pediatricians, especially those in the primary care setting, serve a particularly critical role in the identification and care of those children affected by anemia. Prompt recognition of these risk factors is crucial for developing appropriate and timely therapeutic interventions and prevention strategies.

Evaluating the Diagnostic Performance of Hemoglobin in the Diagnosis of Iron Deficiency Anemia in High-Altitude Populations: A Scoping Review

We evaluated the available literature on the diagnostic performance of hemoglobin (Hb) in the diagnosis of iron deficiency anemia (IDA) in high-altitude populations. We searched PubMed, Web of Science, Scopus, Embase, Medline by Ovid, the Cochrane Library, and LILCAS until 3 May 2022. We included studies that evaluated the diagnostic performance (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), receiver operating characteristic (ROC) curves, and accuracy) of Hb (with and without an altitude correction factor) compared to any iron deficiency (ID) marker (e.g., ferritin, soluble transferrin receptor (sTFR), transferrin saturation, or total body iron (TBI)) in populations residing at altitudes (≥1000 m above sea level). We identified a total of 14 studies (with 4522 participants). We found disagreement in diagnostic performance test values between the studies, both in those comparing hemoglobin with and in those comparing hemoglobin without a correction factor for altitude. Sensitivity ranged from 7% to 100%, whereas specificity ranged from 30% to 100%. Three studies reported higher accuracy of uncorrected versus altitude-corrected hemoglobin. Similarly, two studies found that not correcting hemoglobin for altitude improved the receiver operating characteristic (ROC) curves for the diagnosis of iron deficiency anemia. Available studies on high-altitude populations suggest that the diagnostic accuracy of Hb is higher when altitude correction is not used. In addition, the high prevalence of anemia in altitude regions could be due to diagnostic misclassification.

Association between hemoglobin and elevation among school-aged children: a verification of proposed adjustments

BACKGROUND

Anemia is defined by a hemoglobin (Hb) concentration lower than normal based on cutoffs specific to age, sex, and pregnancy status. Hemoglobin increases with elevation as an adaptive response to lower blood oxygen saturation, thus, adjusting Hb concentration for elevation is necessary before applying cutoffs.

OBJECTIVE

Recent evidence among preschool-aged children (PSC) and non-pregnant reproductive-aged women (WRA) suggests that current World Health Organization (WHO) recommended Hb adjustments for elevation need updating. To confirm these findings, we examined the cross-sectional association between Hb and elevation among non-pregnant school-age children (SAC).

METHODS

Using data from 9 population-based surveys, we examined 26,518 SAC 5-14 years (54.5% female) with data on Hb and elevation (-6 to 3,834 meters, m). We used generalized linear models to assess the association between Hb and elevation under varying conditions, including controlling for inflammation-corrected iron and vitamin A deficiency. Hemoglobin adjustments for each 500 m increase in elevation were estimated for SAC and compared to existing adjustments and those estimated for PSC and WRA. We evaluated the impact of adjustments on anemia prevalence.

RESULTS

Hemoglobin concentration (g/L) was positively associated with elevation (m). The SAC elevation adjustments were consistent with those reported among PSC and WRA and suggest current recommendations may under-adjust Hb for those residing at lower elevations (<3000 m) and over-adjust Hb for those residing at higher elevations (>3000 m). Among the surveys included, proposed elevation adjustments increased anemia prevalence among SAC by 0 (Ghana, United Kingdom) to 15 (Malawi) percentage points relative to current elevation adjustments.

CONCLUSION

Results confirm that current recommended Hb adjustments for elevation may need updating, and anemia prevalence in SAC may be higher than currently estimated. Findings will inform the WHO reexamination of global guidelines on the use of Hb adjustments for anemia assessment and may result in improved identification and treatment of anemia.

The Increase in Hemoglobin Concentration With Altitude Differs Between World Regions and Is Less in Children Than in Adults

To compensate for decreased oxygen partial pressure, high-altitude residents increase hemoglobin concentrations [Hb]. The elevation varies between world regions, posing problems in defining cutoff values for anemia or polycythemia. The currently used altitude adjustments (World Health Organization [WHO]), however, do not account for regional differences. Data from The Demographic and Health Survey (DHS) Program were analyzed from 32 countries harboring >4% of residents at altitudes above 1000 m. [Hb]-increase, (ΔHb/km altitude) was calculated by linear regression analysis. Tables show 95% reference intervals (RIs) for different altitude ranges, world regions, and age groups. The prevalence of anemia and polycythemia was calculated using regressions in comparison to WHO adjustments. The most pronounced Δ[Hb]/km was found in East Africans and South Americans while [Hb] increased least in South/South-East Asia. In African regions and Middle East, [Hb] was decreased in some altitude regions showing inconsistent changes in different age groups. Of note, in all regions, the Δ[Hb]/km was lower in children than in adults, and in the Middle East, it was even negative. Overall, the Δ[Hb]/km from our analysis differed from the region-independent adjustments currently suggested by the WHO resulting in a lower anemia prevalence at very high altitudes. The distinct patterns of Δ[Hb] with altitude in residents from different world regions imply that one single, region-independent correction factor for altitude is not be applicable for diagnosing abnormal [Hb]. Therefore, we provide regression coefficients and reference-tables that are specific for world regions and altitude ranges to improve diagnosing abnormal [Hb].

Anemia in the pediatric patient

The World Health Organization estimates that approximately a quarter of the world's population suffers from anemia, including almost half of preschool-age children. Globally, iron deficiency anemia is the most common cause of anemia. Other important causes of anemia in children are hemoglobinopathies, infection, and other chronic diseases. Anemia is associated with increased morbidity, including neurologic complications, increased risk of low birth weight, infection, and heart failure, as well as increased mortality. When approaching a child with anemia, detailed historical information, particularly diet, environmental exposures, and family history, often yield important clues to the diagnosis. Dysmorphic features on physical examination may indicate syndromic causes of anemia. Diagnostic testing involves a stepwise approach utilizing various laboratory techniques. The increasing availability of genetic testing is providing new mechanistic insights into inherited anemias and allowing diagnosis in many previously undiagnosed cases. Population-based approaches are being taken to address nutritional anemias. Novel pharmacologic agents and advances in gene therapy-based therapeutics have the potential to ameliorate anemia-associated disease and provide treatment strategies even in the most difficult and complex cases.

Effect of Altitude on Hemoglobin and Red Blood Cell Indices in Adults in Different Regions of Saudi Arabia

Purpose

Complete blood count (CBC) is a commonly used blood test for health checks. This study was conducted to compare CBC from two different altitudes and from sea-level populations in order to suggest correction factor for altitude-related increment on the hemoglobin and red blood cell indices.

Patients and Methods

In this retrospective lab records study, large datasets of CBCs over 5-year period were screened from three different regions of Saudi Arabia, Jeddah (a coastal city), Taif City located at 1879 m above sea level, and Abha City at located 2270 m above sea level. Descriptive analysis and significance testing of the CBC variables at different altitude were compared.

Results

A total of 57,059 participants were included for final analysis. Mean hemoglobin (Hb) concentration (g/dL) was 14.81 for men and 13.77 for women at sea level, whereas Hb concentrations were 15.35 and 14.19 for men and women residing at Taif City, respectively, and 15.40 and 14.71 for men and women at Abha City, respectively. Hemoglobin and other red cell indices were significantly different among men and women across different altitude, except for mean corpuscular volume (MCV). The MCV 95^th percentile range was lower at sea level and both altitudes as compared to current reference range (76-91 fL vs 81-98 fL).

Conclusion

Although altitude-associated increment in Hb concentration was evident in both men and women, it was lower than as suggested by World Health Organization and Centers for Disease and Control. Results of this study can also be used to derive new CBC reference intervals for Saudi residents living at high altitude. A correction factor (ΔHb) of 0.30 g/dL per 1000 m altitude is suggested to be used in adult population living at high altitudes in Saudi Arabia which should help better define anemia and polycythemia at altitude.

Hematological Reference Values According to Geographical Region in Jujuy, Argentina

Armella, Flavia Noelia, and Sandra Stella Lazarte. Hematological reference values according to geographical region in Jujuy, Argentina. High Alt Med Biol 00:000-000, 2022. Background: Hematological values vary with altitude above sea level. The purpose of this work was to determine the ranges of hematological reference, and the prevalence of anemia and erythrocytosis in adult blood donors from Jujuy, discriminated according to the geographical region, who assisted at the Centro Regional de Hemoterapia from 2016 to 2018. Materials and Methods: A cross-sectional retrospective study was carried out. Men and women donors belonging to the regions of Valles, Yungas, Quebrada, and Puna were analyzed. The percentiles 2.5 and 97.5 were obtained for the hemoglobin (Hb), hematocrit (Ht), red blood cell count (RBCC), and hematimetric indices, according to sex and region. Results: A total of 4,707 men and 3,326 women, ranging from 18 to 65 years of age, who met with the expected clinical criteria in donors, were studied. The anemia prevalence was 2.5% (95% confidence interval [CI] = 2.2%-2.8%), while the erythrocytosis was 4.9% (95% CI = 4.4%-5.4%). The RBCC, Hb, and Ht increased with altitude above sea level. Conclusions: The Hb and Ht were similar to those observed in the Andean populations living at similar altitudes. The anemia prevalence was lower than the global prevalence reported by the World Health Organization, while that of erythrocytosis increased with the altitude above the sea level. The evidence indicates the necessity for laboratories to obtain reference values for their target population. Registro Nacional de Investigaciones (Renis, Ministerio de Salud de Argentina) IS002323.

Association between iron supplementation and the presence of diarrhoea in Peruvian children aged 6-59 months: analysis of the database of the Demographic and Family Health Survey in Peru (DHS, Peru), years 2009-2019

INTRODUCTION

According to the WHO, anaemia is a severe public health problem when the prevalence is ≥ 40 %. In 2019, in Peru, 40·1 % of children (aged 6 to 35 months) are diagnosed as anaemic. This is a concern since, despite the efforts of the governments to reduce the prevalence, the problem has stagnated since 2011. The treatment applied to deal with anaemia is Fe supplementation. Although Fe is essential for cell function, an excess can produce adverse responses, such as gut inflammation affecting microbiota and resulting in diarrhoeic episodes.

OBJECTIVE

To determine the association between diarrhoea and Fe supplementation in children with and without anaemia, controlling for different socio-demographic variables.

DESIGN

We conducted via logistic regression to obtain diarrhoea prevalence ratios (PR), adjusted by age, sex, geographic region, water and sanitation service, and rurality. The survey asked for recent episodes of diarrhoea during the last 7 d; similarly, after the consumption of Fe supplements during the last 12 months before the survey.

SETTING

Peru.

PARTICIPANTS

The Demographic and Family Health Survey (DHS) is conducted annually at home among 14 202 children on average (2009-2019).

RESULTS

Fe supplementation in the last 7 d (PR = 1·09) or the last 12 months (PR = 1·19) (P < 0·0001) was associated with an increased risk of diarrhoea. The same association was observed between Fe supplementation and the presence of anaemia.

CONCLUSIONS

Fe supplementation is associated with diarrhoea and overuse in children should be avoided.

Changes in hemoglobin levels with age and altitude in preschool-aged children in Peru: the assessment of two individual-based national databases

According to the World Health Organization, the cutoff hemoglobin (Hb) value for defining anemia is 11 g/dL in preschool-aged children, and Hb measurements should be corrected above an altitude of 1000 meters. This study sought to determine the altitude at which the Hb value increases compared with that at sea level, Hb changes with age and region in Peru, the prevalence of anemia according to three different models used to correct Hb for altitude, and the association of the Hb value with stunting. Two individual-based Peruvian national databases were analyzed. Hb increased from an altitude of 375 meters. Hb concentration was lower at younger ages and higher at older ages. The increase in Hb with increasing altitude was lower in southern Peru. Implementing the different models for Hb measurement correction resulted in a higher and lower prevalence of anemia at altitudes >2500 and <2500 m, respectively, using the CDC adjustment. In children aged 6-23 months, the rate of stunting was lower in those with an Hb level of 10-12 g/dL (including mild anemia). In conclusion, the adjustment of Hb values for altitude should be considered before 1000 m and reference ranges should be adjusted to smaller groups of children instead of the same reference range for children aged 6-59 months.

Geographical ancestry affects normal hemoglobin values in high-altitude residents

Increasing the hemoglobin (Hb) concentration is a major mechanism adjusting arterial oxygen content to decreased oxygen partial pressure of inspired air at high altitude. Approximately 5% of the world's population living at altitudes higher than 1,500 m shows this adaptive mechanism. Notably, there is a wide variation in the extent of increase in Hb concentration among different populations. This short review summarizes available information on Hb concentrations of high-altitude residents living at comparable altitudes (3,500-4,500 m) in different regions of the world. An increased Hb concentration is found in all high-altitude populations. The highest mean Hb concentration was found in adult male Andean residents and in Han Chinese living at high altitude, whereas it was lowest in Ethiopians, Tibetans, and Sherpas. A lower plasma volume in Andean high-altitude natives may offer a partial explanation. Indeed, male Andean high-altitude natives have a lower plasma volume than Tibetans and Ethiopians. Moreover, Hb values were lower in adult, nonpregnant females than in males; differences between populations of different ancestry were less pronounced. Various genetic polymorphisms were detected in high-altitude residents thought to favor life in a hypoxic environment, some of which correlate with the relatively low Hb concentration in the Tibetans and Ethiopians, whereas differences in angiotensin-converting enzyme allele distribution may be related to elevated Hb in the Andeans. Taken together, these results indicate different sensitivity of oxygen dependent control of erythropoiesis or plasma volume among populations of different geographical ancestry, offering explanations for differences in the Hb concentration at high altitude.

Travel Time to Health Facilities as a Marker of Geographical Accessibility Across Heterogeneous Land Coverage in Peru

To better estimate the travel time to the most proximate health care facility (HCF) and determine differences across heterogeneous land coverage types, this study explored the use of a novel cloud-based geospatial modeling approach. Geospatial data of 145,134 cities and villages and 8,067 HCF were gathered with land coverage types, roads and river networks, and digital elevation data to produce high-resolution (30 m) estimates of travel time to HCFs across Peru. This study estimated important variations in travel time to HCFs between urban and rural settings and major land coverage types in Peru. The median travel time to primary, secondary, and tertiary HCFs was 1.9-, 2.3-, and 2.2-fold higher in rural than urban settings, respectively. This study provides a new methodology to estimate the travel time to HCFs as a tool to enhance the understanding and characterization of the profiles of accessibility to HCFs in low- and middle-income countries.

Soluble transferrin receptor level, inflammation markers, malaria, alpha-thalassemia and selenium status are the major predictors of hemoglobin in children 6-23 months in Malawi

In sub-Saharan Africa, nearly three-fourths of children 6-23 months are anemic. Yet, the underlying causes had not been sufficiently explored. This study, based on data (n = 348) extracted from the Malawi Micronutrient Survey-2015/2016 dataset, evaluated the contribution of multiple factors to the hemoglobin status of children 6-23 months. The association between hemoglobin and 19 predictors was assessed using multiple linear regression analysis, and the relative contribution of the covariates was determined based on delta-R 2 value. The study found that 43.9% of children were anemic and 76.9% had elevated soluble transferrin receptor (sTfR) levels. Unit changes in serum ferritin (µg/L) and sTfR (mg/L) were associated with 0.01 g/dl rise (p = .041) and 0.05 g/dl decline (p < .001) in hemoglobin, respectively. Each 1 ng/ml increase in plasma selenium was met with 0.007 g/dl (p = .02) rise in hemoglobin. Hemoglobin showed negative relationships with α-1-acid glycoprotein (AGP) (β = -.339, p = .007) and C-reactive protein (CRP) (β = -.014, p = .004) and positive association with child's age in months (β = .038, p = .003) and altitude in meters (β = .001, p = .015). Children affected by α-thalassemia (β = -.75, p < .001), malaria (β = -.43, p = .029), and fever (β = -.39, p = .008) had significantly lower hemoglobin levels. On the contrary, nine variables including serum zinc and retinol binding protein were not significant predictors of hemoglobin. sTfR had the highest delta-R 2 contribution (9.1%) to hemoglobin variations, followed by inflammation (5.2%), α-thalassemia (2.5%), age (2.1%), fever (1.9%), and malaria (1.5%). The analysis suggested iron status, inflammation, and malaria were the major predictors of hemoglobin among Malawian infants and young children.

Is the prevalence of anemia in children living at high altitudes real? An observational study in Peru

Anemia diagnosis in populations residing at high altitude (HA) involves an adjustment of hemoglobin (Hb) values owing to the increase in its concentration with altitude. The suitability of the adjustment has been questioned since Hb concentrations depend on how adapted a population is to HA. In Peru, anemia in preschool children (PSC) is a matter of severe public concern for its high rates; in the city of Puno (∼3800 MASL), for example, 67.7% of children under 3 years are diagnosed with anemia. Here, we conducted an observational study in PSC living at different altitudes in Puno to assess Hb, iron status, and the suitability of altitude-adjusted Hb values in defining iron deficiency anemia. After adjusting Hb, 65.66% of the population had anemia, while only 4.8% of PSC had anemia when using unadjusted Hb. Receiver-operating characteristic curves using total body iron (TBI) as a marker of iron status are presented. In the 36- to 59-month age group, unadjusted Hb performed better than altitude-adjusted Hb. In the 6- to 35-month age group, anemia (adjusted or unadjusted) was not associated with TBI. We conclude that Hb adjustment by altitude is not appropriate. Anemia at an early age is not entirely attributable to iron deficiency.

Elevated Hair Mercury Levels Are Associated With Neurodevelopmental Deficits in Children Living Near Artisanal and Small-Scale Gold Mining in Peru

Children living near artisanal and small-scale gold mining (ASGM) are at risk of exposure to mercury, a neurotoxicant. It is not certain whether such exposures are harming development, as they occur in underresourced contexts entwined with other stressors, such as malnutrition and enteric infection. This study sought to investigate the association between hair-mercury levels and visual-motor, cognitive, and physical development among children living near ASGM in the Peruvian Amazon. Total hair-mercury levels were measured in 164 children ages 5-12 living in Madre de Dios, Peru. Primary outcomes included Visual-Motor Integration assessed via the Beery-VMI Developmental Test, General Cognitive Ability assessed via the Batería-III Woodcock-Munoz (Spanish-language Woodcock-Johnson Tests of Cognitive Abilities), and Physical Health assessed via anthropometry/hemoglobin counts. Mean (SD) hair-mercury level was 2.06 (2.43) μg/g. Fifty-four children (32.9%) had hair-mercury levels above the World Health Organization reference level of 2.0 μg/g. After controlling for sex, child age, maternal education, and family socioeconomic status, each one unit increase in log hair-mercury level was associated with a 1.01 unit decrease in Visual-Motor Integration (95%CI: -2.06, 0.05, p = 0.061), a 2.59 unit decrease in General Cognitive Ability (95%CI: -4.52, -0.66, p = 0.012), and a 2.43 unit decrease in Physical Health (95%CI: -5.34, 0.49, p = 0.096). After adjustment for covariates, children with hair-mercury levels exceeding the World Health Organization reference level scored 4.68 IQ points lower in Cognitive Ability than their peers. Mercury exposures related to ASGM may be harming child development in the Peruvian Amazon. Children in this region may benefit from intervention to reach their full developmental potential.

The relationship between residential altitude and stunting: evidence from >26 000 children living in highlands and lowlands of Ethiopia

Little information is known about the influence of altitude on child growth in Ethiopia, where most people live in highlands. We investigated the relation of residential altitude with growth faltering (stunting) of infants and young children in Ethiopia. We also examined whether the altitude-growth relationship was independent of the influence of the dietary and non-dietary determinants of growth. We used the data of 26 976 under-5-year-old children included in the Ethiopian Demographic and Health Surveys, conducted from 2005 to 2016. The samples were recruited following a two-stage cluster sampling strategy. Stunting was defined by height-for-age <-2 z-scores. The relationship between residential altitude and stunting was examined by running multiple logistic regression analysis, controlling the effect of covariate dietary and non-dietary variables. The residential altitude of the study participants ranged from -116 to 4500 m above sea level (masl). There was a significant and progressive increase in the prevalence and odds of stunting with increasing altitude (P < 0·001), irrespective of the dietary and non-dietary predictors of stunting. The prevalence of stunting was lowest in lowlands (39 %) and highest in highlands (47 %). Compared with altitude <1000 masl, the odds of stunting was 1·41 times higher at altitude ≥2500 masl (OR 1·41, 95 % CI 1·16, 1·71) and 1·29 times higher at altitude 2000-2499 masl (OR 1·29, 95 % CI 1·11, 1·49). Children living in highlands might be at a higher risk of poor growth. Further studies are warranted to understand the mechanism behind the observed altitude-stunting link and identify strategies to compensate for the growth-faltering effect of living in highlands.

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

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.

Reexamination of hemoglobin adjustments to define anemia: altitude and smoking

The correct interpretation of hemoglobin (Hb) to identify anemia requires adjusting for altitude and smoking. Current adjustments were derived using data collected before 1985, from low-income preschool-aged children (PSC) in the United States and indigenous men in Peru for altitude, and from White women of reproductive age (WRA) in the United States for smoking. Given the oldness and limited representativeness of these data, we reexamined associations between Hb and altitude and/or smoking using 13 population-based surveys and 1 cohort study each conducted after 2000. All WHO regions except South-East Asia were represented. The dataset included 68,193 observations among PSC (6-59 months) and nonpregnant WRA (15-49 years) with data on Hb and altitude (-28 to 4000 m), and 19,826 observations among WRA with data on Hb and smoking (status or daily cigarette quantity). Generalized linear models were used to assess the robustness of associations under varying conditions, including controlling for inflammation-corrected iron and vitamin A deficiency. Our study confirms that Hb should be adjusted for altitude and/or smoking; these adjustments are additive. However, recommendations for Hb adjustment likely need updating. Notably, current recommendations may underadjust Hb for light smokers and for those residing at lower altitudes and overadjust Hb for those residing at higher altitudes.