ORIGINAL ARTICLE

A low cost, colour coded, hand held spring scale accurately categorises birth weight in low resource settings

L C Mullany¹, G L Darmstadt², P Coffey³, S K Khatry⁴, S C LeClerq⁴, J M Tielsch¹

¹ Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
² Saving Newborn Lives, Save the Children-US (SC), 2000 M Street, NW, Suite 500, Washington DC, USA
³ Program for Appropriate Technology in Health (PATH), 1455 NW Leary Way, Seattle, USA
⁴ Nepal Nutrition Intervention Project, Sarlahi (NNIPS) PO Box 335, Katmandu, Nepal

Correspondence to:
Dr Gary L Darmstadt
Department of International Health, E-8153, Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolfe Street, Baltimore, MD 21205-2103, USA; gdarmsta{at}jhsph.edu

Aims: To determine the accuracy of a low cost, spring calibrated, hand held scale in classifying newborns into three weight categories (2500 g, 2000–2499 g, <2000 g).

Methods: The test device was compared to a gold standard digital baby scale with precision to 2 g. In Sarlahi district, Nepal, 1890 newborns were eligible for the study. Measurements were collected for both the test device and the digital scale from 1820 (96.3%) newborns.

Results: The overall low birth weight (LBW) prevalence rate for the gold standard digital scale was 28.1% (511/1820). Sensitivity (93.7%) and specificity (97.6%) of the test device was high compared to LBW classifications based on digital weight measurements. Classification of infants into the <2000 g category was 5.0% and 4.7% for the gold standard and test device, respectively. Sensitivity and specificity of the test device in identifying infants <2000 g was 87.8% and 99.6%, respectively. Positive predictive values were high (>91%) for both weight categories

Conclusions: This low cost, simple-to-use device classified infants into weight categories with a high degree of consistency and accuracy that exceeds that of surrogate measures. This new device is useful for identifying and targeting life saving interventions for LBW, high risk infants in settings where infants are born in the home and conventional weighing scales are unavailable.

Keywords: low birth weight; neonatal; scale; sensitivity; specificity; validity

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