Conception and design: Lam. Acquisition of data: Lam, Melkonian. Analysis and interpretation of data: Lam, Lin, Melkonian. Drafting the article: Lin. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Lam. Statistical analysis: Lin, Melkonian. Administrative/technical/material support: Lam, Jea. Study supervision: Lam.