Latent class growth analysis identified childhood wheeze phenotypes

Latent class growth analysis is an effective tool for assessing over time the effects of a child’s environment and outcomes on his or her wheezing, according to study results.

In a study in New York City, conducted from October 1998 to May 2011, the mothers of 689 children were given multiple questionnaires (n=7,048) in order to assess wheeze phenotypes in the children.

The mothers, all of whom were either Dominican (64.4%) or black, did not smoke, nor did they have diabetes, hypertension, or HIV. Each was asked questions in person seven times: when their child was aged 6, 12, 24, 36, 60, 84, and 108 months. They also were questioned by telephone eight times, occurring when their child was aged 3, 9, 15, 18, 21, 30, 48, and 72 months.

They were asked one question each time, in either Spanish or English: “In the past 3 months has your child had wheezing or whistling in the chest.

Investigators divided the study into two parts. First, they identified the number of latent classes (ie, phenotypes) with latent class growth analysis (LCGA) and compared them with longitudinal latent class analysis (LLCA), a statistical method used to group individuals into phenotypes.

The investigators said the LCGA model determined the number of phenotypes “by selecting the model with a minimum value of Bayesian Information Criterion, an information criterion that combines goodness of fit” with economy of the model.

The second part of the analysis introduced covariates to predict phenotypes. These covariates included the mother’s ethnicity and whether she had asthma (22.5%), whether the child was prenatally exposed to tobacco smoke (35.0%), and the child’s gender (51.8% girls).

Four types of wheeze phenotypes in the children were identified by LCGA: never/infrequent wheezing (47.1%), early-transient wheezing (37.5%), late-onset wheezing (7.8%), and early-persistent wheezing (7.6%).

Children whose mothers had asthma were more likely to belong to all but the never/infrequent phenotype. Boys were more likely to develop early-persistent wheezing phenotypes. Children with Dominican mothers were more apt to be in the early-transient phenotype than those with black mothers.

“LCGA may be particularly advantageous when studying the effects of repeated environmental exposures and outcomes that vary over time through childhood,” researchers concluded.