Early childhood undernutrition increases risk of hearing loss in young adulthood in rural Nepal

BACKGROUND: Prevalence of young adult hearing loss is high in low-resource societies; the reasons for this are likely complex but could involve early childhood undernutrition. OBJECTIVE: We evaluated preschool childhood stunting, wasting, and underweight as risk factors for hearing loss in young adulthood in Sarlahi District, southern Nepal. DESIGN: Ear health was assessed in 2006–2008 in a cohort of 2193 subjects aged 16–23 y, who as children <60 mo of age participated in a 16-mo placebo-controlled, randomized vitamin A supplementation trial from 1989 to 1991. At each of five 4-mo assessments, field staff measured children's weight, height, and mid-upper arm circumference (MUAC) and recorded validated parental history of ear discharge in the previous 7 d. Children were classified as stunted [<–2 z score height-for-age (HAZ)], underweight [<–2 z score weight-for-age (WAZ)], or wasted [<–2 z score MUAC-for-age (MUACAZ) or body mass index-for-age (BMIAZ)]. At follow-up, hearing was tested by audiometry and tympanometry, with hearing loss defined as pure-tone average >30dB in the worse ear (0.5, 1, 2, 4 kHz) and middle-ear dysfunction as abnormal tympanometric peak height (<0.3 or >1.4 mmho) or width (<50 or >110 daPa). RESULTS: Hearing loss, present in 5.9% (95% CI: 5.01%, 7.00%) of subjects, was associated with early childhood stunting (OR: 1.64; 95% CI: 1.10, 1.45), underweight (OR: 1.70; 95% CI: 1.18, 2.44) and wasting by BMIAZ (OR: 1.88; 95% CI: 1.19, 2.97) and MUACAZ (OR: 2.14; 95% CI: 1.47, 3.12). Abnormal tympanometry, affecting 16.6% (95% CI: 15.06%, 18.18%), was associated with underweight (OR: 1.46; 95% CI: 1.16, 1.84) and wasting by BMIAZ (OR: 1.80; 95% CI: 1.32, 2.46) and MUACAZ (OR: 1.42; 95% CI: 1.10, 1.84), but not stunting (OR: 1.18; 95% CI: 0.93, 1.49) in early childhood. Highest ORs were observed for subjects with both hearing loss and abnormal tympanometry, ranging from 1.87 to 2.24 (all lower 95% CI >1.00). CONCLUSIONS: Early childhood undernutrition is a modifiable risk factor for early adulthood hearing loss.