Modern biomedical datasets are increasingly high dimensional and exhibit
complex correlation structures. Generalized Linear Mixed Models (GLMMs) have
long been employed to account for such dependencies. However, proper
specification of the fixed and random effects in GLMMs is increasingly
difficult in high dimensions, and computational complexity grows with
increasing dimension of the random effects. We present a novel reformulation of
the GLMM using a factor model decomposition of the random effects, enabling
scalable computation of GLMMs in high dimensions by reducing the latent space
from a large number of random effects to a smaller set of latent factors. We
also extend our prior work to estimate model parameters using a modified Monte
Carlo Expectation Conditional Minimization algorithm, allowing us to perform
variable selection on both the fixed and random effects simultaneously. We show
through simulation that through this factor model decomposition, our method can
fit high dimensional penalized GLMMs faster than comparable methods and more
easily scale to larger dimensions not previously seen in existing approaches