Objective The study objective was to compare haemoglobin (Hb) measurements between the NBM 200 (non-invasive Hb sensor) and Sahli's haemometer in adolescent girls in a rural Indian setting.

Methods Participants included girls aged between 13 and 17 years from 34 villages in Tuljapur and Lohara blocks of Osmanabad district, Maharashtra, India. Hb measurements from the non-invasive sensor (NBM 200) were compared with measurements obtained from Sahli's haemometer using the Bland-Altman plot, Spearman correlation coefficient, sensitivity, specificity and area under the receiver operating characteristic curve analysis (AUROC).

Results Paired measurements from both methods were obtained from 766 adolescent girls (N=766). Hb levels estimated by Sahli's haemometer ranged from 5.0 to 14.0 g/dL (mean 10.1 g/dL, SD 1.41), whereas measurements obtained from the NBM 200 ranged from 9.5 to 15.2 g/dL (mean 12.8 g/dL, SD 1.42). The Bland-Altman analysis indicated a mean difference of −2.70 g/dL (95% CI −2.84 to −2.55) demonstrating an overestimation of Hb measurement by the NBM 200 compared with the Sahli's haemometer measurements. The NBM 200 showed low sensitivity (23.6%) and moderate specificity (61.8%) for the diagnosis of anaemia. The AUROC score was 0.43 indicating an underestimation of anaemia in our study population by the NBM 200.

Conclusions Hb measurements obtained from the NBM 200 were consistently higher leading to an underestimation of prevalence of anaemia compared with Sahli's haemometer estimates among adolescent girls in India.