Aims Growth charts are widely used to assess child nutritional status and health. New charts based on 2006 WHO growth standards are currently being rolled out to replace old National Centre for Health Statistics (NCHS) growth references. Though technically superior, there are concerns that different WHO cutoffs for low weight-for-height (<−2 and <−3 z-scores for moderately and severely low) might result in more infants aged <6 months being inappropriately diagnosed as undernourished. We aimed to assess whether and how different growth charts influence healthcare workers' clinical decisions about infants aged <6 months.
Methods A randomised crossover trial involving 79 healthcare workers (doctors, clinical officers, healthcare assistants) from six randomly sampled centres was conducted in Southern Malawi. Participants were offered hypothetical clinical/growth scenarios based the same infant plotted on NCHS references and new WHO standards growth charts. Scenarios also compared growth charts showing a single measurement versus a series of measurements (a favourable growth trend upwards, in parallel to the reference lines). Scenarios were presented in random order. Participants were blind to the study hypothesis and the fact that paired charts showing the very same infants were being presented. The (i) level of concern; and likelihood of (ii) referral or (iii) interruption of breastfeeding were elicited through an interview-questionnaire.
Results Participants showed (i) increased concern (Wilcoxon Ranked Sum Test, p<0.01) when growth was plotted on the WHO charts rather than on NCHS charts, were (ii) 2.1 times more likely to refer or admit (RR 2.1; 95%CI (1.5 to 2.8);p=0.04) and (iii) 1.5 times more likely to counsel practices which interrupt exclusive breastfeeding [RR 1.5; 95%CI (1.1 to 2.1); p<0.01]. Favourable growth trend rather than a single measurement showed no difference in (i) concern, (ii) referral or (iii) feeding advice.
Conclusions Using WHO Growth Standards in developing countries may increase inappropriate referrals for infant <6 m malnutrition and have a detrimental effect on exclusive breastfeeding. It appears that healthcare workers do not take into account a steady long term trend if the final measurement is below the new threshold values. Improved training on implementation and interpretation of the new WHO Standards is important to mitigate these effects.