Determinants of vitamin a deficiency in children between 6 months and 2 years of age in Guinea-Bissau

Abstract

BackgroundThe World Health Organization (WHO) classifies Guinea-Bissau as having severe vitamin A deficiency (VAD). To date, no national survey has been conducted. We assessed vitamin A status among children in rural Guinea-Bissau to assess status and identify risk factors for VAD.MethodsIn a vitamin A supplementation trial in rural Guinea-Bissau, children aged 6 months to 2 years who were missing one or more vaccines were enrolled, vaccinated and randomized to vitamin A or placebo. Provided consent, a dried blood spot (DBS) sample was obtained from a subgroup of participants prior to supplementation. Vitamin A status and current infection was assessed by an ELISA measuring retinol-binding protein (RBP) and C-reactive protein (CRP). VAD was defined as RBP concentrations equivalent to plasma retinol <0.7 μmol/L; infection was defined as CRP >5 ml/L. In Poisson regression models providing prevalence ratios (PR), we investigated putative risk factors for VAD including sex, age, child factors, maternal factors, season (rainy: June-November; dry: December-May), geography, and use of health services.ResultsBased on DBS from 1102 children, the VAD prevalence was 65.7% (95% confidence interval 62.9-68.5), 11% higher than the WHO estimate of 54.7% (9.9-93.0). If children with infection were excluded, the prevalence was 60.2% (56.7-63.7). In the age group 9–11 months, there was no difference in prevalence of VAD among children who had received previous vaccines in a timely fashion and those who had not. Controlled for infection and other determinants of VAD, the prevalence of VAD was 1.64 (1.49-1.81) times higher in the rainy season compared to the dry, and varied up to 2-fold between ethnic groups and regions. Compared with having an inactivated vaccine as the most recent vaccine, having a live vaccine as the most recent vaccination was associated with lower prevalence of VAD (PR=0.84 (0.74-0.96)).ConclusionsThe prevalence of VAD was high in rural Guinea-Bissau. VAD varied significantly with season, ethnicity, region, and vaccination status.Trial registrationClinicaltrials.gov NCT00514891

Vitamin A status and associated factors in infants attending at Primary Health Care in Goiânia, Goiás, Brazil

“…Even though the general prevalence of VAD in this study is 14.0%, this prevalence was overestimated in 4.1% after excluding the children with subclinical infection (PCR > 5 mg/L). Similar overestimations in the real prevalence of VAD were found in the analyses by Queiroz et al 13 (2.0%) and Danneskiold-Samsøe et al 26 (5.5%), who used CRP ≥ 6 mg/L and CRP > 5mg/L as cutoff points for infection, respectively.…”

High-dose Vitamin A With Vaccination After 6 Months of Age: A Randomized Trial

“…Vitamin A status did not differ by gender (Table 1). 26 Eight deaths due to accidents (VAS: 2, placebo: 6) (Supplemental Table 6) were censored on the date of death (Fig 1), leaving 80 nonaccident deaths (VAS: 38, placebo: 42) within 6 months and 137 nonaccident deaths (VAS: 66; placebo: 71) within 12 months of followup.…”

“…As specified in the protocol, secondary outcomes are reported elsewhere. 26,27 The follow-up for mortality ended at whichever came first: subsequent VAS, 12 months of follow-up, first visit after February 24, 2011 (when another trial was initiated), or at latest July 21, 2011 when the code was broken. When a death was registered, an interview was conducted on the circumstances leading to the death.…”

“…Finger prick blood samples were obtained and analyzed from 15% of the participants to assess vitamin A status 26 (Supplemental Information).…”

The immunological effects of oral polio vaccine provided with BCG vaccine at birth: A randomised trial

“…From the DBSs, RBP and CRP were measured concurrently by a combined simple sandwich ELISA method [8,9]. The samples were tested in duplicates with the paired baseline and follow-up samples in the same assay.…”