Influences on catch-up growth using relative versus absolute metrics: evidence from the MAL-ED cohort study
Authors: Richard Stephanie A. , McCormick Benjamin J. J. , Murray-Kolb Laura E. , Bessong Pascal , Shrestha Sanjaya K. , Mduma Estomih , Ahmed Tahmeed , Kang Gagandeep , Lee Gwenyth O. , Seidman Jessica C. , Svensen Erling , Kosek Margaret N. , Caulfield Laura E. ,   MAL-ED Network Investigators, Acosta Angel Mendez , de Burga Rosa Rios , Chavez Cesar Banda , Flores Julian Torres , Olotegui Maribel Paredes , Pinedo Silvia Rengifo , Salas Mery Siguas , Trigoso Dixner Rengifo , Vasquez Angel Orbe , Ahmed Imran , Alam Didar , Ali Asad , Bhutta Zulfiqar A. , Qureshi Shahida , Rasheed Muneera , Soofi Sajid , Turab Ali , Yousafzai Aisha , Zaidi Anita K. M. , Bodhidatta Ladaporn , Ammu Geetha , Babji Sudhir , Bose Anuradha , George Ajila T. , Hariraju Dinesh , Jennifer M. Steffi , John Sushil , Kaki Shiny , Kang Gagandeep , Karunakaran Priyadarshani , Koshy Beena , Lazarus Robin P. , Muliyi Jayaprakash , Ragasudha Preethi , Raghava Mohan Venkata , Raju Sophy , Ramachandran Anup , Ramadas Rakhi , Ramanujam Karthikeyan , Rose Anuradha , Roshan Reeba , Sharma Srujan L. , Shanmuga Sundaram E. , Thomas Rahul J. , Pan William K. , Ambikapathi Ramya , Carreon J. Daniel , Doan Viyada , Hoest Christel , Knobler Stacey , McCormick Benjamin J. J. , McGrath Monica , Miller Mark A. , Psaki Stephanie , Rasmussen Zeba , Richard Stephanie A. , Seidman Jessica C. , Gottlieb Michael , Lang Dennis R. , Tountas Karen H. , Svensen Erling , Amour Caroline , Bayyo Eliwaza , Mduma Estomih R. , Mvungi Regisiana , Nshama Rosemary , Pascal John , Swema Buliga Mujaga , Yarrot Ladislaus , Mason Carl J. , Ahmed Tahmeed , Ahmed A. M. Shamsir , Alam Md Ashraful , Haque Rashidul , Haque Umma , Hossain Md Iqbal , Islam Munirul , Mahfuz Mustafa , Mondal Dinesh , Nahar Baitun , Tofail Fahmida , Chandyo Ram Krishna , Shrestha Prakash Sunder , Shrestha Rita , Ulak Manjeswori , Bauck Aubrey , Black Robert E. , Caulfield Laura E. , Checkley William , Kosek Margaret N. , Lee Gwenyth O. , Schulze Kerry , Yori Pablo Peñataro , Murray-Kolb Laura E. , Ross A. Catharine , Schaefer Barbara , Simons Suzanne , Pendergast Laura , Abreu Cláudia B. , Costa Hilda , Di Moura Alessandra , Filho José Quirino , Havt Alexandre , Leite Álvaro M. , Lima Aldo A. M. , Lima Noélia L. , Lima Ila F. , Maciel Bruna L. L. , Medeiros Pedro H. Q. S. , Moraes Milena , Mota Francisco S. , Oriá Reinaldo B. , Quetz Josiane , Soares Alberto M. , Mota Rosa M. S. , Patil Crystal L. , Bessong Pascal , Mahopo Cloupas , Maphula Angelina , Nyathi Emanuel , Samie Amidou , Barrett Leah , Dillingham Rebecca , Gratz Jean , Guerrant Richard L. , Houpt Eric , Petri William A. , Platts-Mills James , Rogawski Elizabeth , Scharf Rebecca , Rogawski Elizabeth T. , Shrestha Binob , Rayamajhi Bishnu Bahadur , Shrestha Sanjaya Kumar , Strand Tor 
Published: June 2021

Abstract
Background
Poor growth in early childhood has been considered irreversible after 2–3 years of age and has been associated with morbidity and mortality over the short-term and with poor economic and cognitive outcomes over the long-term. The MAL-ED cohort study was performed in eight low-income settings with the goal of evaluating relationships between the child’s environment and experience (dietary, illness, and pathogen exposure, among others) and their growth and development. The goal of this analysis is to determine whether there are differences in the factors associated with growth from 24 to 60 months using two different metrics.

Methods
Across six MAL-ED sites, 942 children had anthropometry data at 24 and 60 months, as well as information about socioeconomic status, maternal height, gut permeability (lactulose-mannitol z-score (LMZ)), dietary intake from 9 to 24 months, and micronutrient status. Anthropometric changes were in height- or weight-for-age z-score (HAZ, WAZ), their absolute difference from the growth standard median (HAD (cm), WAD (kg)), as well as recovery from stunting/underweight. Outcomes were modeled using multivariate regression.

Results
At 24 months, almost half of the cohort was stunted (45%) and 21% were underweight. Among those who were stunted at 24 months (n = 426), 185 (43%) were no longer stunted at 60 months. Most children increased their HAZ from 24 to 60 months (81%), whereas fewer (33%) had positive changes in their HAD. Linear regression models indicate that girls improved less than boys from 24 to 60 months (HAZ: -0.21 (95% CI -0.27, -0.15); HAD: -0.75 (-1.07, -0.43)). Greater intestinal permeability (higher LMZ) at 0–24 months was associated with lower relative and absolute changes from 24 to 60 months (HAZ: -0.10 (-0.16, -0.04); HAD: -0.47 (-0.73, -0.21)). Maternal height (per 10 cm) was positively associated with changes (HAZ: 0.09 (0.03, 0.15); HAD: 0.45 (0.15, 0.75)). Similar relationships were identified for changes in WAZ and WAD.

Conclusions
The study children demonstrated improved growth from 24 to 60 months of age, but only a subset had positive changes in HAD and WAD. The same environmental factors were associated with growth from 24 to 60 months regardless of metric used (change in HAZ or HAD, or WAZ and WAD).