Evaluation of the hemoglobin cutoff point for anemia in adult women residents of different altitudinal levels in Peru

by Cinthya Vásquez-Velásquez, Gustavo F. Gonzales

Anemia prevalence is high in countries where high proportion of the population lives at high altitude (HA) due perhaps to the unsuitability hemoglobin correction factor proposed by the WHO. The present study has been designed to evaluate a new approach to establish thresholds of hemoglobin (Hb) when defining anemia at HA.

Cross-sectional study evaluating 217 women aged 18 to 75 years-old, residents of 2 cities at low altitude (LA) (130 and 150 meters) and 2 at HA (3800 and 4300 meters). Hb, pulse oxygen saturation (SpO₂), arterial oxygen content (CaO₂), and inflammatory markers were measured. Three definitions of anemia diagnoses were used: uncorrected Hb, WHO-corrected Hb, and Silubonde’s criteria based on ferritin as a gold standard. STATA v18.0 was use for data analysis, p<0.05 indicated significant difference.

HA residents present higher Hb values than at LA. Likewise, the highest area under the curve (AUC) ROC (Receiver Operating Characteristic) was observed for uncorrected Hb (AUC = 0.8595; CI95% 0.858–0.86) for the diagnosis of anemia using serum ferritin as the gold standard. Anemia prevalence was higher when using WHO-corrected Hb, 27%, and Silubonde’s criteria, 41% (Hb cut-off of 11.10, 12.73, 15.80 and 16.60 g/dl for altitudes of 130, 150, 3800 and 4300 meters, respectively), than using uncorrected Hb to define anemia (7.7%). Serum Ferritin and CaO₂ values are lower only in the group with anemia defined with uncorrected Hb than in the groups of anemia using the WHO-corrected Hb or the Silubonde´s criteria.

The correction factor of hemoglobin for altitude of residence overestimates the prevalence of anemia in adult women. Likewise, CaO₂ could be a potential marker to determine the transport of oxygen in LA and HA populations. Further studies in adult men are required to confirm the present findings.