The reliability of a newborn foot length measurement tool used by community volunteers to identify low birth weight or premature babies born at home in southern Tanzania.

Tanya Marchant,Fatuma Manzi,Donat Shamba,Joanna Schellenberg,Suzanne Penfold,Jennie Jaribu,Elibariki Mkumbo

doi:10.1186/1471-2458-14-859

Abstract

BackgroundLow birthweight babies need extra care, and families need to know whether their newborn is low birthweight in settings where many births are at home and weighing scales are largely absent. In the context of a trial to improve newborn health in southern Tanzania, a counselling card was developed that incorporated a newborn foot length measurement tool to screen newborns for low birth weight and prematurity. This was used by community volunteers at home visits and shows a scale picture of a newborn foot with markers for a ‘short foot’ (<8 cm). The tool built on previous hospital based research that found newborn foot length <8 cm to have sensitivity and specificity to identify low birthweight (<2500 g) of 87% and 60% respectively.MethodsReliability of the tool used by community volunteers to identify newborns with short feet was tested. Between July-December 2010 a researcher accompanied volunteers to the homes of babies younger than seven days and conducted paired measures of newborn foot length using the counselling card tool and using a plastic ruler. Intra-method reliability of foot length measures was assessed using kappa scores, and differences between measurers were analysed using Bland and Altman plots.Results142 paired measures were conducted. The kappa statistic for the foot length tool to classify newborns as having small feet indicated that it was moderately reliable when applied by volunteers, with a kappa score of 0.53 (95% confidence interval 0.40 – 0.66) . Examination of differences revealed that community volunteers systematically underestimated the length of newborn feet compared to the researcher (mean difference −0.26 cm (95% confidence interval −0.31—0.22), thus overestimating the number of newborns needing extra care.ConclusionsThe newborn foot length tool used by community volunteers to identify small babies born at home was moderately reliable in southern Tanzania where a large number of births occur at home and scales are not available. Newborn foot length is not the best anthropometric proxy for birthweight but was simple to implement at home in the first days of life when the risk of newborn death is highest.

Highlights

Low birthweight babies need extra care, and families need to know whether their newborn is low birthweight in settings where many births are at home and weighing scales are largely absent
Categorising babies as small using the counselling card Forty six percent of newborns were categorised as having short foot length (
There was a positive skew in the distribution of difference between researcher and volunteer measures (Figure 2), and after plotting the difference against the average of paired measures no evidence of bias for different sized feet was observed (Figure 3). In this community based study we have shown that a newborn foot length measurement tool, printed on a counselling card, can be used at the community level with moderate reliability by community volunteers who have received 5 days of training in total, which included approximately 5 hours on foot size measurement

Summary

Introduction

Low birthweight babies need extra care, and families need to know whether their newborn is low birthweight in settings where many births are at home and weighing scales are largely absent. In the context of a trial to improve newborn health in southern Tanzania, a counselling card was developed that incorporated a newborn foot length measurement tool to screen newborns for low birth weight and prematurity This was used by community volunteers at home visits and shows a scale picture of a newborn foot with markers for a ‘short foot’ (

Methods

Results

Discussion

Conclusion